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Monarch Watch Update February 2022

9 February 2022 | Author: Jim Lovett

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Greetings Monarch Watchers!

This is a relatively brief update, primarily serving as a follow-up to some items in last month’s email. Thank you for your continued interest and support!

Included in this issue:
1. Monarch Watch One Day Fundraising Event
2. Monarch Watch Tag Recoveries
3. Free Milkweed Programs
4. A Return to the Monarch Puzzle
5. About This Monarch Watch List

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1. Monarch Watch One Day Fundraising Event
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As promised last month, below is the official announcement of this year’s one day fundraising event taking place next week. We will send out a reminder on the day of the event to give you easy access to the link, should you like to participate. Help us continue our mission to restore habitats for monarchs and native pollinators – donations of any amount do help and are greatly appreciated.

On Thursday, February 17th Monarch Watch will again be featured in the University of Kansas’ annual “One Day. One KU.” 24-hour fundraising campaign. This event provides an opportunity for Monarch Watchers all over the globe to come together and show their support of our programs.

This year you will be able to take advantage of FOUR matching opportunities to increase the impact of your gift:

1. Monarch Watch Director Chip Taylor and his wife, Toni, are matching dollar-for-dollar all gifts up to $4,000.

2. Dedicated supporter, Janet Lanza, will match dollar-for-dollar all gifts to Monarch Watch, up to $5,000!

3. KU alumna and Monarch Watch supporter, Susan Lordi Marker, will match dollar-for-dollar all gifts, up to $5,000!

4. An anonymous donor will match dollar-for-dollar all gifts up to $5,000 to Monarch Watch and encourages others to donate.

Additionally, many employers will match employee gifts to Monarch Watch so that is yet another opportunity!

To make a donation online the day of the event, visit https://kansas.scalefunder.com/amb/monarch

To make a gift by phone anytime between now and the day of the event, call KU Endowment at (888) 653-6111 – just be sure to mention that you would like to give in support of Monarch Watch for the one-day event.

Don’t forget to check your email on February 17th for the reminder and link – thank you!

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2. Monarch Watch Tag Recoveries
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Many of you have been asking about when tag recoveries for the 2021 tagging season will be posted online.

Recoveries from the overwintering sites in central Mexico are typically reported to us in February/March and posted online in March/April once everything is received and verified. We will make an announcement via our email updates so stay tuned!

The tag recoveries within the U.S., Canada and northern Mexico are typically posted in January/February once everything has been vetted – a link to the list is now posted online at https://monarchwatch.org/tagrecoveries

As a reminder, if you have not submitted your tagging data to us yet, it is not too late! Complete information (including links to the tag data submission form and recovery lists) is available on our Monarch Tagging Program page at https://monarchwatch.org/tagging

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3. Free Milkweed Programs
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For habitat restoration projects

New this year, we will be able to distribute free milkweeds to many areas of California (in addition to areas east of the Rocky Mountains) – please see the link below for complete details. To qualify, applicants must have a minimum of two acres (one acre in CA) to restore to natural, native habitat, and have a management plan in place. Milkweeds are awarded on a first come, first served basis, so apply early.

Those awarded free milkweeds need only pay shipping/handling, which is modest compared to the value of the plants. Please help us spread the word by sharing widely. For more information and to apply, please visit:

https://monarchwatch.org/free-milkweed-restoration

For Schools and Nonprofits

The Free Milkweeds for Schools and Nonprofits Grant is in its 8th year and we are still distributing free milkweeds to those who qualify. Through the generous support of the Natural Resources Defense Council, this program provides funding for 6000 plants. Each recipient receives one full flat of milkweed plants to be added to a public garden. Schools, libraries, nature centers and museums are examples of past recipients. This program is available to applicants in California and all states east of the Rocky Mountains. The application can be found here:

https://monarchwatch.org/free-milkweed-schools-nonprofits

Sorry, this program is not intended for private yards or free milkweed giveaways.

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4. A Monarch Puzzle – Chip Taylor
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The contest is still on.

“When does the migration northward end – or does it”?

In a monthly update posted in June of 2003 with the above title, I wrote “My guess is that the migration stops at each degree of latitude northward at a particular date, that these dates can be predicted, and that all directional migration stops before the 21st of June at all latitudes.” Over the years I have returned to that question several times and have asked myself repeatedly what might the monarchs be responding to that would stop directional flight. The question is basically – what is changing and how is that change perceived by the monarchs? Further, whatever the cue is, it has to be similar over all latitudes.

So, what could it be? I think I’ve figured it out, and I think you can too. That was the basis for the puzzle in the last email update (see original text below). The challenge was to identify a factor common to all locations that could explain why monarchs would stop directional flight on a certain date.

Fourteen people submitted answers to the puzzle by the end of January. None of them arrived at the answer I was seeking and that’s not surprising. It’s a difficult question, and it took me a long time to arrive at the pattern that I think explains when monarchs stop directional flight in late May to early June from Dallas to Winnipeg.

All of the respondents mentioned seasonal changes, and these ranged from temperatures and winds to changes in vegetation, daylength and sun angle. However, none of them pointed to a specific change that was common to all four sites – specifically a change that the monarchs might respond to.

I’m confident that many of you can get to the answer I did, and to get you there, I’m are going review a few things and direct you to a website. (In the original puzzle, the dates for St. Paul and Winnipeg were incorrect, being 9 and 12 respectively. They are corrected in the table below).

Table 1. Seasonal metrics for specific locations.

Location	Date	Daylength	Sun angle (SASN)	Solstice	22nd
Lawrence, KS	5 June	14h48m12s	73.63°	74.47°	74.46°
Ames, IA	7 June	15h9m33s	70.78°	71.42°	71.41°
St. Paul, MN	8 June	15h31m41s	67.95°	68.50°	68.49°
Winnipeg, CAN	11 June	16h18m0s	63.23°	63.55°	63.54°

It’s clear from this table that daylength, sun angle at solar noon and at the solstice (21 June) all change with date and latitude. So, none of these changes per se can explain why monarchs might stop migrating on the dates suggested. Yet, there is change. So, the question becomes is there a feature of the changes that are occurring that is common to all locations? There are a number of sources on the internet that are useful in this context. My favorite is SunCalc ( https://suncalc.org )

For a short tutorial on how to use SunCalc please visit https://monarchwatch.org/blog/2021/08/17/some-notes-on-the-sun-angle-at-solar-noon-sasn-and-the-passage-of-the-migration/

Table 1 was assembled using SunCalc, but there is more that can be learned using this site. To get to where I did, think about what the monarchs may or may not be responding to as the season changes. You can get to the answer using suncalc.org, and if you get there, you may react the way I did. It was kind of a eureka moment – except I didn’t say eureka!

If you think you have figured out what these four locations have in common on the dates indicated and have an explanation for why migratory flight probably stops on these dates, send your answer to Monarch Watch at monarch@ku.edu (with “Puzzle Submission” in the Subject line) by the 28th of February 2022. We will reward the three best answers with a copy of the new migration board game “Mariposas”.

A Monarch Puzzle – original text

Get out your pencils!

We know that directional flight (migration) by first generation monarchs that have moved northward stops sometime in June, but we aren’t sure when it stops, where it stops or why. I have an idea based on one data point that may explain the when and why for a series of latitudes. I’m going to explain the observation and tell you when I expect directional flight ends at the latitudes of Ames, IA, St Paul, MN and Winnipeg, Manitoba.

Many years ago, I asked an undergraduate to pay special attention to directional flight by monarchs in late May and June. We knew that first generation monarchs from the South Region (Texas and Oklahoma) were moving through the area at that time on the way north to the summer breeding grounds north of 40N. We also knew that that migration stopped suddenly but we didn’t know when or why. She went to a location with lots of common milkweed patches at which the passing monarchs would stop briefly but then continue flying N/NE. The last day she spotted monarchs moving to the N/NE was the 5th of June. That got me thinking, if I know when they stopped in Lawrence, could I extrapolate from the conditions on the 5th of June to those in other latitudes? Well, I’ve done so, and the prediction is that directional flight should stop in Ames on the 7th, in St Paul on the 9th and Winnipeg on the 12th.

So here is the puzzle: what do the dates at the latitudes represented by these cities have in common with the conditions that occur on the 5th of June in Lawrence, Kansas?

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5. About This Monarch Watch List
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Monarch Watch ( https://monarchwatch.org ) is a nonprofit education, conservation, and research program affiliated with the Kansas Biological Survey & Center for Ecological Research at the University of Kansas. The program strives to provide the public with information about the biology of monarch butterflies, their spectacular migration, and how to use monarchs to further science education in primary and secondary schools. Monarch Watch engages in research on monarch migration biology and monarch population dynamics to better understand how to conserve the monarch migration and also promotes the protection of monarch habitats throughout North America.

We rely on private contributions to support the program and we need your help! Please consider making a tax-deductible donation. Complete details are available at https://monarchwatch.org/donate or you can simply call 785-832-7374 (KU Endowment Association) for more information about giving to Monarch Watch.

If you have any questions about this email or any of our programs, please feel free to contact us anytime.

Thank you for your continued interest and support!

Jim Lovett
Monarch Watch
https://monarchwatch.org

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Monarch Watch Update January 2022

6 January 2022 | Author: Jim Lovett

Greetings Monarch Watchers and Happy New Year to all!

As many of you already know, Monarch Watch will be celebrating 30 years of education, conservation, and research in 2022 – WOW! We are not yet sure how we will mark this milestone, but there will certainly be a retrospective component and maybe an event or two. We will keep you informed via our blog, email updates, and social media. Thank you for your continued interest and support!

Included in this issue:
1. How Many Hectares in 2021-2022?
2. Western Monarchs
3. Monarch Watch One Day Fundraising Event
4. Monarch Watch Tagging Kits for 2022
5. Submitting Tag Data
6. Monarch Watch Mobile App
7. Free Milkweed Programs
8. A Monarch Puzzle
9. About This Monarch Watch List

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1. How Many Hectares in 2021-2022? – Chip Taylor
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Each year, at about this time, I administer a test – to myself. I have one question. How big, in term of hectares*, will the overwintering population be this year?

Technically, I fail the test every time and expect to. Realistically, it would be virtually impossible to correctly predict the overwintering numbers given the number of variables involved in each migration.

I look at many factors and draw on the historical record to arrive at a prediction. The conditions during the spring in Texas, the recolonization of the northern breeding areas in May, the summer temperatures, the weather during the migration and the availability of nectar sources in Texas all differ from year to year and all factor into the number of monarchs that reach the overwintering sites. The challenge for me is to assess each of these conditions for a given year and to compare these outcomes with the record that goes back to 1994.

After considering all of these factors for this past season, I came up with the following estimate: 0.8-1.2 hectares. Ouch! That’s low and lower than the 2.01 hectares measured last year. In fact, if 1.2 hectares this year, that would be the lowest number since the winter of 2014-2015. I know that that is not what anyone wants to hear, and I don’t want to accept those numbers myself, but that is what my assessment tells me. My history with these estimates is fair, but I usually underestimate the size of the population which means that I’m overestimating the negative impact of one or more factors. These over and under estimates speak to my goal which is to develop a deep understanding of all the factors that determine the size of the population. Being wrong goes along with learning how to refine my estimates. Last year my estimate for the hectare total was almost spot on – 2.0 hectares vs a measured 2.01 hectares. It was more of a guess than a data-based prediction, but I’ll take credit for being close. There are reasons to think I will be close again this year and other reasons to predict that the number will be higher.

For a detailed discussion of this season’s prediction please see the expanded “How many hectares in 2021-2022?” article posted today via the Monarch Watch blog.

*One hectare is equal to 2.47 acres. One acre is approximately the area of a football field exclusive of the end zones.

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2. Western Monarchs – Chip Taylor
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My father was a Certified Public Accountant, and had I demonstrated a facility for numbers, I might have become a CPA as well. Instead, I became a biologist which I naively assumed would mean that I wouldn’t have to work with numbers – at least not a lot. As it turns out, understanding monarchs, or more accurately, attempting to understand monarchs, requires a lot of number crunching. But that only works if we have some numbers to work with, and if the numbers are reasonably accurate.

This brings me to a monarch puzzle. Namely, how did the Western monarch population grow from an overwintering number of 1,914 in 2020 to over 200,000 in 2021? Both numbers are based on Xerces-sponsored Thanksgiving Day Counts. Each count involves an examination and estimation of the number of monarchs at 261 known overwintering locations and the search for new sites which are often on private land. At many sites, the number of monarchs is so low, the count is an actual count rather than an estimate. That was mostly the case last year and the Thanksgiving number was followed by an end of the year accounting that produced only 1,049 monarchs. The decline from 1,914 to 1,049 was not unexpected. From the end of a breeding season in September and October (depending on location), the population declines until the end of the first reproductive period in April.

There seem to be three possibilities, 1) monarchs originating from Mexico recolonized the breeding areas in the West in March and April, 2) there were thousands of overwintering monarchs that clustered at sites that have never been discovered or 3) that some monarchs that breed along the coast during the winter months responded to seasonal cues in March and moved inland where they gave rise to a first generation of monarchs that colonized the summer breeding ranges in the West, particularly those areas to the east and north of California.

I’ve attempted to determine if there is support for any of these possibilities and those interested in a deep dive into the numbers should read the expanded “Western Monarchs” article posted today via the Monarch Watch blog.

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3. Monarch Watch One Day Fundraising Event
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Monarch Watch will again be featured in the University of Kansas’ annual “One Day. One KU.” 24-hour fundraising campaign which will take place in mid-February. The event will provide an opportunity for Monarch Watchers all over the globe to come together and show their support of our program.

Last year many of you commented that you would’ve liked more notice of this event so this is just a quick heads up before an official announcement that will be made in the coming weeks. Stay tuned!

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4. Monarch Watch Tagging Kits for 2022
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Monarch tagging continues to be an important tool to help us understand the monarch migration and annual cycle. We are now accepting PREORDERS for the 2022 fall tagging season and kits will be sent out in the fall, ahead of the migration in your area. If you would like to tag monarchs this year, please order your tags as early as possible!

Monarch Watch Tagging Kits are only shipped to areas east of the Rocky Mountains. Each tagging kit includes a set of specially manufactured monarch butterfly tags (you specify quantity), a data sheet, tagging instructions, and additional monarch / migration information. Tagging Kits for the 2022 season start at only $15 and include your choice of 25, 50, 100, 200, or 500 tags.

Monarch Watch Tagging Kits and other materials (don’t forget a net!) are available via the Monarch Watch Shop online at https://shop.monarchwatch.org – where each purchase helps support Monarch Watch.

Complete information including datasheets and instructions are available on the Monarch Tagging Program page at https://monarchwatch.org/tagging

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5. Submitting Tag Data
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Thousands of you have submitted your recent tag data to us by mail or via our online submission form – thank you! We are still receiving data sheets and if you haven’t submitted your data yet (for 2021 or even previous years) it is not too late. Please review the “Submitting Your Tagging Data” information on the tagging program page then send us your data via the Tagging Data Submission Form.

Complete information is available at https://monarchwatch.org/tagging if you have questions about submitting your data to us and we have conveniently placed a large “Submit Your Tagging Data” button on our homepage at https://monarchwatch.org that will take you directly to the online form.

There you can upload your data sheets as an Excel or other spreadsheet file (PREFERRED; download a template file from https://monarchwatch.org/tagging ) or a PDF/image file (scan or photo).

If you have any questions about getting your data to us, please feel free to drop Jim a line anytime via JLOVETT@KU.EDU

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6. Monarch Watch Mobile App
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A newly developed Monarch Watch mobile app (for iOS and Android) will make it easier for many taggers to record butterflies as they are tagged and submit data electronically. The beta testing of the app in the last few months has gone well, and we hope to launch it for general use during the 2022 tagging season. We will have much more to say about this in the coming months.

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7. Free Milkweed Programs
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For habitat restoration projects

New for Spring 2022 — Free Milkweeds for California restoration!

Monarch Watch will once again be distributing free milkweeds for planting in large-scale habitat restoration projects for Spring 2022. Since this program began in 2015, almost 252,000 milkweeds [edit: more than 650,000 milkweeds] have been planted in restored habitat throughout much of the range of the eastern monarch population. New this year: Help the Western monarch population with FREE MILKWEEDS FOR MOST AREAS OF CALIFORNIA! To qualify, applicants must have a minimum of two acres (one acre in CA) to restore to natural, native habitat, and have a management plan in place. Milkweeds are awarded on a first come, first served basis, so apply early.

https://monarchwatch.org/free-milkweed-restoration

For Schools and Nonprofits

https://monarchwatch.org/free-milkweed-schools-nonprofits

Sorry, this program is not intended for private yards or free milkweed giveaways.

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8. A Monarch Puzzle – Chip Taylor
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Get out your pencils!

So here is the puzzle: what do the dates at the latitudes represented by these cities have in common with the conditions that occur on the 5th of June in Lawrence, Kansas?

If you think you have figured out what these four locations have in common on the dates indicated and have an explanation for why migratory flight probably stops on these dates, send your answer to Monarch Watch at monarch@ku.edu (with “Puzzle Submission” in the Subject line) by the 31st of January 2022. We will reward the three best answers with a copy of the new migration board game “Mariposas”.

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9. About This Monarch Watch List
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Monarch Watch ( https://monarchwatch.org ) is a nonprofit education, conservation, and research program affiliated with the Kansas Biological Survey & Center for Ecological Research at the University of Kansas. The program strives to provide the public with information about the biology of monarch butterflies, their spectacular migration, and how to use monarchs to further science education in primary and secondary schools. Monarch Watch engages in research on monarch migration biology and monarch population dynamics to better understand how to conserve the monarch migration and also promotes the protection of monarch habitats throughout North America.

If you have any questions about this email or any of our programs, please feel free to contact us anytime.

Thank you for your continued interest and support!

Jim Lovett
Monarch Watch
https://monarchwatch.org

If you would like to receive periodic email updates from Monarch Watch, you may SUBSCRIBE via https://monarchwatch.org/subscribe

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Western Monarchs

6 January 2022 | Author: Chip Taylor

My father was a Certified Public Accountant, and had I demonstrated a facility for numbers, I might have become a CPA as well. Instead, I became a biologist which I naively assumed would mean that I wouldn’t have to work with numbers – at least not a lot. As it turns out, understanding monarchs, or more accurately, attempting to understand monarchs, requires a lot of number crunching. But that only works if we have some numbers to work with, and if the numbers are reasonably accurate, which brings me to a monarch puzzle. Namely, how did the Western monarch population grow from an overwintering number of 1,914 in 2020 to over 200,000 in 2021? Both numbers are based on Xerces sponsored Thanksgiving Day Counts. Each count involves an examination and estimation of the number of monarchs at 261 known overwintering locations and the search for new sites which are often on private land. At many sites, the number of monarchs is so low, the count is an actual count rather than an estimate. That was mostly the case last year and the Thanksgiving number was followed by an end of the year accounting that produced only 1049 monarchs. The decline from 1914 to 1049 was not unexpected. From the end of a breeding season in September and October (depending on location), the population declines until the end of the first reproductive period in April.

So, from a January number of 1049, how many females would we expect to be alive in March at the beginning normal reproduction in California? We can expect attrition to continue from January to March, but let’s assume that 70% survive. That’s probably high, but let’s go with it. That leaves 734 individuals. Since the sex ratio shifts in Mexico from being dominated by males at the beginning of the winter season to being female dominated at the end of the season, let’s assume that applies to these numbers. At best, that would mean that 55-65% of the survivors would be females. Let’s say it’s 60%, or 441 females. The next question is – Is it possible for 441 females to produce a population of 200,000 monarchs in 3-4 generations? I don’t think so. I’ve done the math several times, and you can as well*. So, if we can’t see a way to account for a fall population of 200,000 from the overwintering numbers, it means we are missing something, and the next question is what could that be? There seem to be three possibilities, 1) monarchs originating from Mexico recolonized the breeding areas in the West in March and April, 2) there were thousands of overwintering monarchs that clustered at sites that have never been discovered or 3) that some monarchs that breed along the coast during the winter months responded to seasonal cues in March and moved inland where they gave rise to a first generation of monarchs that colonized the summer breeding ranges in the West, particularly those areas to the east and north of California.

To determine if there is any support for the idea that the West was recolonized by monarchs from Mexico, I examined the first sightings records posted to Journey North and all the images of monarchs posted to iNaturalist for March and April. There is nothing on either site that supports the hypothesis that monarchs returned from Mexico in good numbers this past spring. If they did, this influx was missed by all those who are inclined to report monarch sightings.

The possibility that there are coastal or even inland overwintering sites in California that have never been discovered is real. New sites are discovered from time to time. Given the length of the coastal area, and the possibility that some areas are relatively inaccessible, there is the possibility that thousands of monarchs overwintered at locations that weren’t part of the surveys in 2020. There are reasons to think that the conditions for establishing overwintering clusters were different in 2020. The mean temperatures in California for both September and October 2020 were the highest in the record. October was +6.7F above the long-term average. It is during these months that monarchs migrate toward the coast with numbers beginning to show up at the overwintering sites in mid-October. Monarchs don’t migrate when the temperatures are in the 90s and often not when in the mid 80s. Rather, they seek cooler sites. This behavior might have led them to cluster in atypical locations. Under these conditions, monarchs that are unable to avoid extreme high temperatures often become reproductive and drop out of the migration. Both of these things could have happened in September-October 2020. Although it’s possible, even likely, that there are alternative overwintering sites in California, there is simply no evidence that such sites played a role in the number of monarchs that survived the winter in 2020-2021.

The third explanation, that offspring of winter breeding monarchs moved inland to reproduce in March and April is a possibility but, again, there is no precedent for such an occurrence. However, given the widespread reproduction this past winter reported to the Monarch Larval Monitoring Project (view summary of California data by year), this possibility shouldn’t be discounted. The fact is, we know little about the population dynamics of monarchs that reproduce during the winter months in California. So, what is the possibility that some recently emerged offspring of coastal breeding monarchs do move inland in March to reproduce? To answer that question, we need to know how monarchs respond to seasonal cues that might initiate migratory behavior. To dive into that topic, let’s look at the daylength/celestial conditions that occur during the migration northward in Mexico to see if they apply to California. We know that mating increases at the overwintering sites in Mexico in mid-February after the sun angle at solar noon (SASN) increases to 57 degrees. The date of the migration northward from the colonies is temperature dependent but usually starts around the 1st of March. The SASN at that time is 63 degrees. The possibility that the northward migration from Mexico is associated changes in the SASN is supported by the graphic (Fig 1) David Gibo and I put together based on first sightings assembled by Elizabeth Howard and her team at Journey North years ago**. The 63 SASN for a beginning of the departure from Mexico doesn’t seem to match a tracking of 56 SASN once the monarchs reach Texas. However, it is possible that the cues to leave actually began weeks earlier when the SASN reached 56 or 57 degrees. Preparing for departure from the colonies may in fact take several weeks since it is still cool at the Mexican sites, especially at night, which could delay the physiological and behavioral responses to the changing conditions. Once monarchs leave the overwintering colonies, they encounter consistently higher temperatures and move northward about 50-55 miles a day, which is faster than the pace of the SASN in degrees. The SASN advances about one degree, or 69 miles, every three days***. The difference in the respective paces allows the butterflies to soon track an SASN of 56 degrees – if the weather allows.

As to prepping to leave the coastal areas for the interior, cool conditions along the coast and the nearby foothills could result in a delay in physiological and behavioral development and could determine when monarchs move inland. It may help, when thinking of these dynamics, to remember that overwintering monarchs have a low metabolic rate which increases once they respond sufficiently to seasonal conditions to become reproductive. Further, when thinking about the possibility that breeding monarchs along the coast might move inland, that may only apply to newly emerged monarchs that have yet to become reproductive. From all we have been able to ascertain, once late summer monarchs become reproductive, they do not migrate even if exposed to seasonal changes that result in migration by younger cohorts. In effect, once reproductive, older adults appear to be insensitive or “blind” to seasonal cues. Mating is delayed in monarchs with most mating occurring on days 3-5 post emergence. That coincides with ovary development and the production of juvenile hormone. My guess is that the conditions experienced during these first 3-5 days determine whether monarchs migrate. If I’m correct, newly emerged monarchs that result from continuous breeding along the coast, if exposed to seasonal cues that signal migration, would do so. There is no a priori reason to expect that that would not happen. Still, there are reasons to be skeptical about whether this scenario played out last March and April. We know too little about winter breeding along the coast. We need to know the where and when new adults are produced as well as their numbers.

Some may also wonder whether conditions seen in Mexico apply to California. They probably do. The following is a summary of the first day that the SASN reaches 56 degrees in California locations along with cities in Texas and Oklahoma. These dates and latitudes are represented in Fig. 1. These comparisons suggest that, at least in terms of daylength associated celestial cues, Western and Eastern monarchs are exposed to similar conditions.

Table 1. March dates SASN reaches 56 degrees in California, Texas and Oklahoma

Date	Location 1	Location 2
17 March	San Diego, CA (32°42'56")	Dallas, TX (32°48'20")
21 March	Ventura, CA (34°15'17")	Ardmore, OK (34°9'9")
23 March	Pismo Beach, CA (35°9'12")	Okmulgee, OK (35°38'5")
27 March	Pacific Grove, CA (36°37'13")	Enid, OK (36°24'8")

Figure 1. A few monarchs from Mexico appear to reach Texas during the first week of March when the SASN is close to 56 degrees. As monarchs continue to arrive from Mexico and move further north in Texas and into Oklahoma, they appear to be tracking an SASN of 56 until the third week of April. By that date, most have died and there is a drop in sightings until the first-generation monarchs begin moving north in late April and May.

Conclusion

So, how can we explain the difference in the overwintering numbers from 2020 to 2021? Two things seem unlikely. It doesn’t seem possible that the few hundred females that survived from last year’s overwintering population could account for over 200,000 monarchs this year. Nor is there any evidence that monarchs arrived in the inner West in March and April from Mexico. That leaves us with the possibility that there were unfound overwintering sites with thousands, perhaps 10’s of thousands of monarchs, and the possibility that offspring of coastal breeding monarchs moved inland and generated a first generation that colonized the breeding areas in the inner West and the northwestern states. The problem is there is no evidence for either – although both may have occurred. There is at least one other approach. We can use what is known about monarch population dynamics to bracket the possible number of females it took to produce more than 200,000 adults – a lot more in fact – since we need to account for attrition during the migration. Those calculations will have to wait until we get the final numbers, but see the notes below.

Notes

*Here are a few of the details that are required to calculate population increases. First, you have to know, or estimate, the number of females at the start of a generation. Then, you need to estimate the mean number of eggs produced per female (250-350). That is followed by an estimate of the survival to the pupal stage (0.01 or more) and then the survival of pupae to adult (0.76). Since not all adults reproduce, you need another estimate of those numbers (0.85). The last multiplier is the proportion of females which is generally close to 0.45.

Here is an example calculation:

1000 x 250 = 250,000 x 0.01 = 2500 x 0.76 = 1900 x 0.85 = 1615 x 0.45 = 727. Hmmm, those numbers don’t work since you end up with fewer females than we started with. If we increase the egg to pupal survival to 0.03 we get the following.

1000 x 250 = 250,000 x 0.03 = 7500 x 0.76 = 5700 x 0.85 = 4845 x 0.45 = 2180. That yields a 2.2-fold increase. Even after 4 generations that rate of increase isn’t sufficient to generate more than 200,000 migrants.

Perhaps I’m missing something or underestimating egg numbers or survival, but if these calculations are even close, they suggest that thousands of females were required to produce this year’s overwintering numbers. That said, we haven’t accounted for the attrition during the migration made by the first generation as it moves into the inner west and the northwestern states. Two things could happen. The number of females surviving to reproduce would be reduced, and the mean number of eggs per female would decline as well, not only due to a reduction in the size of the cohort, but because the search time for host plants is likely to increase, especially in the West. If there is either a significant loss of the first-generation females during colonization or significant reduction in mean egg number, it would be difficult for the population to produce an overwintering population of >200K. The keys to population growth are the number of females at the start of each generation and, in the case of monarchs West and East, the size of the first generation and its success in reaching the main summer breeding grounds. Again, those considerations suggest that a relatively large number of females had to be involved in the establishment of the first-generation last year.

The calculations I’ve used assume constant rates of mortality from one generation to the next. However, the incidence of parasitism by tachinid flies and O. e. tends to increase as the season progresses. Such increases would reduce both the proportion of larvae reaching the pupal stage and surviving to the adult stage. In the case of the adults with O. e., their fitness to reproduce would be compromised. We also need to recognize that realized fecundity, i.e., the mean eggs per female per generation, varies with temperature, nectar availability, and the distribution, abundance and quality of milkweeds. These factors also affect population growth.

** In subsequent years, especially in 2012 and 2017, it became apparent that high March temperatures and strong southwesterly winds allowed monarchs to advance much faster than expected for SASN. It was cooler in March in Texas from 1997 to 2000 than it has been in recent years.

*** Actually, the SASN advance averages less than 69 miles per day over the entire migration, but three days per degree of latitude is a useful reference point for discussion.

Relevant literature

Altizer, S., Oberhauser, K. S., and L.P. Brower. 2000. Associations between host migration and the prevalence of a protozoan parasite in natural populations of monarch butterflies Ecological Entomology 25(2):125 – 139 DOI:10.1046/j.1365-2311.2000.00246.x

Brower, L.P. and R.M. Pyle. 2004. The interchange of migratory monarchs between Mexico and the Western United States, and the importance of floral corridors in the fall and spring migrations. In Conserving Migratory Pollinators and Nectar Corridors in Western North America, edited by G. Nabhan, 144-166. Tucson: University of Arizona Press.

Grant, T. J., D. T. T. Flockhart, T. R. Blader, R. L. Hellmich, G. M. Pitman, S. Tyner, D. R. Norris, and S. P.Bradbury. 2020. Estimating arthropod survival probability from field counts: a case study with monarch butterflies. Ecosphere 11(4):e03082. 10.1002/ecs2.3082

James, D.G.; Schaefer,M.C.; Krimmer Easton, K.; Carl, A. First Population Study on Winter Breeding Monarch Butterflies, Danaus plexippus (Lepidoptera: Nymphalidae) in the Urban South Bay of San Francisco, California. Insects 2021, 12, 946. https://doi.org/10.3390/ insects12100946

Nail, K. R., C. Stenoien, and K. S. Oberhauser. 2015. Immature monarch survival: effects of site characteristics, density, and time. Annals of the Entomological Society of America 108:680–690.

Oberhauser, K., R. Wiederholt, J. E. Diffendorfer, D.Semmens, L. Ries, W. E. Thogmartin, L. Lopez-Hoffman, and B. Semmens. 2017. A trans-nationalmonarch butterfly population model and implica-tions for regional conservation priorities. EcologicalEntomology 42:51–60.

Semmens, B. X., D. J. Semmens, W. E. Thogmartin, R.Wiederholt, L. Lopez-Hoffman, J. E. Diffendorfer, J.M. Pleasants, K. S. Oberhauser, and O. R. Taylor.2016. Quasi-extinction risk and population targets for the Eastern, migratory population of monarch butterflies (Danaus plexippus). Scientific Reports6:23265.

Taylor OR Jr, Lovett JP, Gibo DL, Weiser EL, Thogmartin WE, Semmens DJ, Diffendorfer JE, Pleasants JM, Pecoraro SD and Grundel R (2019) Is the Timing, Pace, and Success of the Monarch Migration Associated With Sun Angle? Front. Ecol. Evol. 7:442. doi: 10.3389/fevo.2019.0044

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How many hectares in 2021-2022?

6 January 2022 | Author: Chip Taylor

Each year, at about this time, I administer a test – to myself. I have one question. How big, in term of hectares*, will the overwintering population be this year? Technically, I fail the test every time and expect to. Realistically, it would be virtually impossible to correctly predict the overwintering numbers given the number of variables involved in each migration. For example, there is no way to predict the weather conditions in Mexico that determine how tightly the monarchs are clustered when measured during mid-December. There are other variables in Mexico as well – such as the density of the forest. What I’m alluding to is that a hectare in one part of the forest could represent a widely different number of monarchs from a hectare in another location. So, the bottom line is that everything is an estimate, and we don’t know how well the hectares from one year compare to those of another. While that is true, the hectare measure seems to represent the size of the population fairly well. For example, the number of monarchs tagged in the Midwest each fall is strongly correlated with the overwintering number. That would not be true if there was a lot of error in the number of hectares and the number of butterflies per hectare following each migration.

So, if the number of tagged butterflies can be used to predict the overwintering population, why don’t I just use those numbers as predictors? Unfortunately, it takes months and months to assemble all the tagging records for a given year. Therefore, I have to look to other measures or conditions and draw on the historical record to arrive at a prediction. The conditions during the spring in Texas, the recolonization of the northern breeding areas in May, the summer temperatures, the weather during the migration and the availability of nectar sources in Texas all differ from year to year and all factor into the number of monarchs that reach the overwintering sites. The challenge for me is to assess each of these conditions for a given year and to compare these outcomes with the record that goes back to 1994.

After considering all of these factors for this past season, I came up with the following estimate – 0.8-1.2 hectares. Ouch! That’s low and lower than the 2.01 hectares measured last year. In fact, if 1.2 hectares this year, that would be the lowest number since the winter of 2014-2015. I know that that is not what anyone wants to hear, and I don’t want to accept those numbers myself, but that is what my assessment tells me. My history with these estimates is fair, but I usually underestimate the size of the population which means that I’m overestimating the negative impact of one or more factors. These over and under estimates speak to my goal which is to develop a deep understanding of all the factors that determine the size of the population. Being wrong goes along with learning how to refine my estimates. Last year my estimate for the hectare total was almost spot on – 2.0 hectares vs a measured 2.01 hectares. It was more of a guess than a data-based prediction, but I’ll take credit for being close. There are reasons to think I will be close again this year and other reasons to predict that the number will be higher.

In the following paragraphs I’ll summarize the reasons for why my prediction might be right or wrong. Although I evaluate data from the entire range of the eastern monarch range, my prediction is largely based on what I can glean about the colonization and population growth that occurs from 90-100W – a region from just west of Madison, WI to the central Dakotas. Tagging results indicate that about 70% of the monarchs that reach the overwintering sites originate from this region.

There are several reasons the monarch numbers at the overwintering sites might be lower this winter than in recent years. First, as shown in the drought monitor images for this past summer (Figs 1-3), there was a severe drought in the Dakotas that extended eastward well into Minnesota. Droughts have a strong negative impact on monarch population development since plant growth is stunted, plant quality declines and nectar is more limited. These conditions decrease monarch longevity and reproductive success. High temperatures, which often accompany drought conditions, also negatively influence population growth. This year, the first sightings posted to Journey North indicated that monarchs arrived in the northern breeding areas on time and in good numbers. However, post arrival, the regional and state temperatures were substantially above the long-term averages for June through August. For example, the average temperatures were +3.1F for the Upper Midwest, +1.2F of the Ohio Valley and +2.8F for the Northeast. The temperatures in the states in the drought areas were +4.3 for North Dakota, +3.9 for South Dakota and +3.8F for Minnesota. The temperature for Minnesota was the second highest since 1895. The temperatures are significant since the record shows that populations decline when the mean temperatures exceed +2F. These above average temperatures persisted into September in the Upper Midwest and the effect was to delay the migration. Again, the tagging data shows that late migrations are associated with lower numbers reaching the overwintering sites.

As to numbers in the migration, Journey North tallies the number of roosts reported by observers. These sightings include estimates of the number of monarchs. A quick scan of these estimates suggested that the numbers for all sightings this year were about half those in 2020. The observations by Harlen and Altus Aschen near Port Lavaca, TX suggested that the flow of monarchs along the Gulf coast, many of which probably originated from the Northeast, was late and involved a relatively small number of monarchs.

In summary, all of the metrics used to assess the size of the summer and migratory populations indicated that the population reaching the overwintering sites would be substantially lower than the number measured in 2020.

There are also reasons why my estimates might be overly pessimistic. A recent report from El Rosario offered that the population this year was about a third larger than last year. Further, in early December, the counts of trees occupied by monarchs at Chincua, Cerro Pelon and Herrada were all greater than I would have expected based on my assessments. We will have to wait for the official counts. I’d be delighted to be wrong – on the low side that is.

*One hectare is equal to 2.47 acres. One acre is approximately the area of a football field exclusive of the end zones.

Figure 1. June Drought Monitor

Figure 2. July Drought Monitor

Figure 3. August Drought Monitor

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2021 year-end summary

31 December 2021 | Author: Jim Lovett

Season’s Greetings from the staff at Monarch Watch!

We would like to thank everyone who contributed to our program in the last year. That support has enabled us to maintain and grow our programs and aid many people in their efforts to create habitats for monarchs. As you know, sustaining the migration is a massive undertaking due to continuing loss of milkweed/monarch habitats. We’ve distributed over one million plants through our Milkweed Market and free milkweeds programs since 2014 but we need to do more. We expanded our efforts in California this past season and distributed about 3,800 plugs of Asclepias fascicularis, the most common hostplant used by monarchs in that state. Our ambitious goal for California in 2022 is the distribution of at least 36,000 milkweed plugs. We will be working with other non-governmental organizations as well as state and federal agencies to find homes for these milkweeds.

Although adjustments to Covid-19 continued with the cancelation of our Spring and Fall Open House events this year, we were able to hold our fall tagging event at the Baker Wetlands to the delight of many families. We had a wonderful day in the great outdoors and there were smiles all around.

The newly developed Monarch Watch mobile app will make it easier for many taggers to record butterflies as they are tagged and submit data electronically. The beta testing of the app has gone well, and we hope to launch it for general use during the 2022 tagging season. We will have much more to say about this in the coming months. As we mentioned last year, two papers have been published recently on the results of the tagging. The data analysis is continuing and two additional papers are well underway. It’s a slow process – lots of data!

This past year, to expand our ability to distribute more milkweeds for restoration projects, we worked closely with the KU Endowment Association to raise funds through the annual “One Day. One KU.” campaign held in February. Hundreds of people responded with contributions sufficient to enable us to distribute an additional 28,000 milkweed plugs and clearly demonstrated the widespread support for monarch and pollinator conservation.

Time flies when you are having fun and that’s also true if you have a vision and a mission and are driven to see it through. That may be fairly said of the Monarch Watch team. Although we often wondered if we would survive financially from one year to the next, Monarch Watch continued to grow and will be celebrating 30 years of education, conservation, and research in 2022! We are not yet sure how we will mark this milestone, but there will certainly be a retrospective component and maybe an event or two. We will keep you informed via our blog, email updates, and social media.

Again, thank you for your continued support and we hope you will be with us again this coming year. Best wishes to you and yours for a happy and healthy holiday season. Please stay safe!

Sincerely,

Chip Taylor, Jim Lovett, Ann Ryan, Angie Babbit and Dena Podrebarac
Team Monarch Watch

To keep up with the status of monarchs and other news, subscribe to our email updates ( monarchwatch.org/subscribe ), join our email discussion list ( monarchwatch.org/dplex ), visit our blog ( monarchwatch.org/blog ) and follow us on Facebook, Instagram, and Twitter.

Monarch Watch
Kansas Biological Survey & Center for Ecological Research
University of Kansas
2021 Constant Avenue
Lawrence, KS 66047
785-864-4441
monarch@ku.edu
monarchwatch.org

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Monarch Watch Update August 2021

23 August 2021 | Author: Jim Lovett

Greetings!

Included in this issue:
1. Monarch Population Status
2. Monarch Watch Tagging Kits
3. Submitting Tag Data
4. Chip in for Monarch Watch
5. Monarch Waystations
6. Upcoming Monarch Watch Events
7. About This Monarch Watch List

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1. Monarch Population Status —by Chip Taylor
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The migration is underway!

EASTERN MONARCHS
As you may remember, earlier I offered that the recolonization this past May and early June of the summer breeding area was quite favorable. Monarchs generally arrived on time and in good numbers leading to a large second generation. Things looked favorable for a large migratory population that could rival that of 2018 (6.05 hectares) – provided that the summer temps were within 2F of the long-term average and that September temperatures in the north were generally normal as well.

I have been following the weather closely for the last several months and things still look good for a large migration over most of the summer breeding area. However, I have doubts about the number of monarchs that will join the migration from the eastern Dakotas and western Minnesota. Portions of that region have been much warmer and drier than is generally ideal for monarch population development.

In contrast, due perhaps to adequate rainfall and moderate summer temperatures, monarchs are much more abundant in Oklahoma and Texas at this time, suggesting that high numbers of monarchs could join the migration from this region in late September and October. The September temperatures are still a question, but there is no evidence of a drought in Texas or elsewhere that might diminish the possibility of surviving the passage to the overwintering sites.

Overall, while the conditions for population growth have been less favorable than in 2018, suggesting an overwintering population of less than 6 hectares, there is every reason to expect a larger overwintering population in Mexico this year than seen during the last two winters (2.83 hectares for 2019-2020 and 2.10 hectares for 2020-2021).

WESTERN MONARCHS
Given the winter, spring, and summer monarch numbers as well as the extreme summer temperatures and drought conditions in the West, the prospects for an overwintering population of more than a few hundred monarchs along the California coast appear to be slim at best.

For those who would like to delve deeper into the timing, pace and duration of the monarch migration, please see a recent post to the Monarch Watch Blog (https://monarchwatch.org/blog): “Some notes on the sun angle at solar noon (SASN) and the passage of the migration”

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2. Monarch Watch Tagging Kits
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We are in the process of sending out tagging kits for our 30th tagging season – wow! As of today, all preorders and most recent orders going to locations north of (and including) Colorado, Kansas, Missouri, Kentucky, and Virginia have been mailed out. If you are located in that area and you have not yet received your tags, watch your mail for them to arrive within the next 10 days or so. Tags for locations further south will be mailed out soon – priority is always given to those tag orders going to locations that will experience the migration first.

Monarch tagging continues to be an important tool to help us understand the monarch migration and annual cycle – a long-term record is crucial to understand the dynamics of such complex natural phenomena. If you would like to tag monarchs this year, please order your tags soon as they are going fast! Tagging Kits should arrive within 10–12 days but as mentioned above, priority will be given to areas experiencing the migration first.

Monarch Watch Tagging Kits are only shipped to areas east of the Rocky Mountains. Each tagging kit includes a set of specially manufactured monarch butterfly tags (you specify quantity), a data sheet, tagging instructions, and additional monarch / migration information. Tagging Kits for the 2021 season start at only $15 and include your choice of 25, 50, 100, 200, or 500 tags.

2021 datasheets and instructions available online via the Monarch Tagging Program page at https://monarchwatch.org/tagging

Tagging should begin in early to mid-August north of 45N latitude (e.g. Minneapolis), late August at other locations north of 35N (e.g., Oklahoma City, Fort Smith, Memphis, Charlotte) and in September and early October in areas south of 35N latitude. See a map and a table with expected peak migration dates on the Monarch Tagging Program page at the link above.

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3. Submitting Tag Data
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Thousands of you have submitted your recent tag data to us by mail or via our online submission form – thank you! We are still receiving data sheets and if you haven’t submitted your data yet (for 2020 or even previous years) it is not too late. Please review the “Submitting Your Tagging Data” information on the tagging program page then send us your data via the Tagging Data Submission Form. For 2021, please submit your data soon after you are finished tagging for the season.

Complete information is available at https://monarchwatch.org/tagging if you have questions about submitting your data to us and we have conveniently placed a large “Submit Your Tagging Data” button on our homepage at https://monarchwatch.org that will take you directly to the online form.

There you can upload your data sheets as an Excel or other spreadsheet file (PREFERRED; download a template file from https://monarchwatch.org/tagging) or a PDF/image file (scan or photo).

If you have any questions about getting your data to us, please feel free to drop Jim a line anytime via JLOVETT@KU.EDU

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4. Chip in for Monarch Watch
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Our “Chip in for Monarch Watch” fundraising campaign was created in honor of our director and founder, Chip Taylor (whose birthday happens to be at the end of August, by the way). This campaign offers a chance for Monarch Watchers, colleagues, friends, and family across the planet to show their support for Chip and the Monarch Watch program he brought to life more than a quarter-century ago. It has provided tremendous support for Monarch Watch over the years, through both monetary contributions and kind words.

We encourage you to spend a little time reading through previous donor comments on the Chip in for Monarch Watch page (https://monarchwatch.org/chip) – the connections that are facilitated by monarchs and Monarch Watch are truly extraordinary.

The 2021 Chip in for Monarch Watch fundraising campaign is now underway! If you are in a position to offer financial support to Monarch Watch (or know someone who might be), please consider making a donation of any amount during this campaign.

Here’s how it works:
1. Donate online via KU Endowment: https://kuendowment.org/monarch (offline options are also available, see below)

2. Submit your pledge, comments, thanks, birthday wishes, photos, etc. for Chip: https://monarchwatch.org/chip/submit

3. We will assemble a donor list, comments, and photos to present to Chip at the end of the campaign.

Donating securely online is easy but if you would rather make a donation by phone or mail please see complete details at https://monarchwatch.org/chip/

Thank you!

Chip in for Monarch Watch: https://monarchwatch.org/chip

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5. Monarch Waystations
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To offset the loss of milkweeds and nectar sources we need to create, conserve, and protect monarch butterfly habitats. You can help by creating “Monarch Waystations” in home gardens, at schools, businesses, parks, zoos, nature centers, along roadsides, and on other unused plots of land. Creating a Monarch Waystation can be as simple as adding milkweeds and nectar sources to existing gardens or maintaining natural habitats with milkweeds. No effort is too small to have a positive impact.

Have you created a habitat for monarchs and other wildlife? If so, help support our conservation efforts by registering your habitat as an official Monarch Waystation today!

https://monarchwatch.org/waystations

A quick online application will register your site and your habitat will be added to the online registry. You will receive a certificate bearing your name and your habitat’s ID that can be used to look up its record. You may also choose to purchase a metal sign to display in your habitat to encourage others to get involved in monarch conservation.

As of 4 August 2021, there have been 35,768 Monarch Waystation habitats registered with Monarch Watch! Texas holds the #1 spot with 2,922 habitats and Illinois (2,789), Michigan (2,662), California (2,319), Ohio (1,863), Florida (1,788), Virginia (1,602), Wisconsin (1,570), Pennsylvania (1,557) and Ontario (1,179) round out the top ten.

You can view the complete listing and a map of approximate locations via https://monarchwatch.org/waystations/registry

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6. Upcoming Monarch Watch Events
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Monarch Watch Fall Open House
Event Canceled 🙁
Lawrence, Kansas

We had hoped to be able to welcome you back to our Fall Open House event, but we are all going to have to wait a bit longer – sorry! We invite you to visit our garden and enjoy our outdoor space on your own this fall. Evenings and/or weekends would be the best time to visit given the parking restrictions on campus. Thank you for your interest and we hope to see you in person soon. Stay safe!

Monarch Watch Tagging Event (Free event)
Saturday, September 18, 2021
Baker Wetlands Discovery Center
Lawrence, Kansas

The tagging has always been an outdoor event so we are still planning to host it in cooperation with the Jayhawk Audubon Society and the Baker Wetlands Discovery Center – it should be similar to previous years. If you’ll be in the Lawrence, Kansas area in September, we’d love for you to join us so mark your calendars and stay tuned to our website, emails and social media for updates.

Complete details: https://monarchwatch.org/tag-event/

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7. About This Monarch Watch List
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Monarch Watch (https://monarchwatch.org) is a nonprofit education, conservation, and research program affiliated with the Kansas Biological Survey & Center for Ecological Research at the University of Kansas. The program strives to provide the public with information about the biology of monarch butterflies, their spectacular migration, and how to use monarchs to further science education in primary and secondary schools. Monarch Watch engages in research on monarch migration biology and monarch population dynamics to better understand how to conserve the monarch migration and also promotes the protection of monarch habitats throughout North America.

If you have any questions about this email or any of our programs, please feel free to contact us anytime.

Thank you for your continued interest and support!

Jim Lovett
Monarch Watch
https://monarchwatch.org

If you would like to receive periodic email updates from Monarch Watch, you may SUBSCRIBE via https://monarchwatch.org/subscribe

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Some notes on the sun angle at solar noon (SASN) and the passage of the migration

17 August 2021 | Author: Chip Taylor

Linking the timing, pace and duration of the migration to the sun angle at solar noon (SASN) was only possible because thousands of volunteers tagged monarchs from the time monarchs emerged in late summer until the end of the migration. We now know that the migration begins when the SASN drops below 57 degrees over all latitudes with the monarchs reaching the overwintering latitude in Mexico when the SASN also has dropped below 57 degrees. We also know how the composition of the migration changes from the beginning to the end of the migration and much more.

My intention with this text is to provide you with a better understanding of how the migration is related to SASN and how you can acquire these values for your location and dates of tagging.

The migration lasts 25-33 days in most locations. That means there is a beginning or leading edge (that can either be awesome or a trickle) a peak or midpoint, which usually contains a large portion of the migrants, and an end, which is modest in most years and dominated by smaller monarchs, of which a high proportion are females (relative to earlier in the migration).

The SASN values that correspond to these phases of the migration are as follows.

Leading edge – SASN less than 57 degrees to 54 degrees

Mid-point – SASN from 53-50 degrees

End – SASN 49-46 degrees

For reference, each SASN degree represents a little less than three days. However, that relationship varies slightly with latitude.

It helps to keep in mind that while the above SASN values represent “average rates of movement” of the migration, the migration advances more slowly when it’s too cold, too hot, too rainy or too windy.

To calculate the SASN for a specific latitude and date, go to suncalc.org.

I entered Lawrence, KS, USA. Then clicked on culmination to get the correct SASN value for today. After that I opened the tool box indicated by T and clicked on date slider to open that feature. Once that was open, I closed the tool box. The slider allows you to change the dates easily.

The first image shows the SASN – 64.52 (Altitude in the column at the left) for Lawrence, KS for today 16 August – and the second shows the SASN for the 7th of September – the first day that the SASN drops below 57 degrees (56.81 degrees) for this latitude (N 38°58’23.05”). This date is the earliest date we might expect to see the arrival of migrants from the north in Lawrence. The migrants can be distinguished from non-migratory monarchs, that is those that are still reproductive, since they exhibit directional flight with a distinct heading. In our area, the mean heading for migrants is 210 degrees.

As mentioned, it is only because monarchs have been tagged from the time they emerged in late summer until the end of the migration and beyond that we have been able learn how the migration functions. Given the changing climate which appears likely to affect the migration more and more in coming years, it’s important for taggers to continue the practice of tagging monarchs from emergence of the last generation until the last monarchs pass through each latitude.

Screenshot images from suncalc.org:

Image 1.

Image 2.

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Monarch Population Status

17 August 2021 | Author: Chip Taylor

The migration is underway!

Filed under Monarch Population Status | Comments Off

Monarch Watch Update July 2021

8 July 2021 | Author: Jim Lovett

This newsletter was sent via email to those who subscribe to our email updates. If you would like to receive periodic email updates from Monarch Watch, please take a moment to complete and submit the short Google Form at https://monarchwatch.org/subscribe/

Greetings Monarch Watchers!

Included in this issue:
1. Monarch Population Status
2. Monarch Watch Tagging Kits for 2021
3. Submitting Tag Data
4. Tagging Wild and Reared Monarchs
5. Monarch Waystations
6. Collect Milkweed Seed for Monarch Watch
7. Monarch Calendar Project
8. Upcoming Monarch Watch Events
9. Monarch Rearing, Tagging and Releasing Survey
10. About This Monarch Watch List

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1. Monarch Population Status —by Chip Taylor
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EASTERN MONARCHS
As you may recall, I was concerned about the conditions monarchs would encounter as they returned from Mexico in March due to the devastating impact of the 11-day freeze in Texas in mid-February. That led to a project to determine 1) how the vegetation recovered from the freezing conditions, 2) the plants the monarchs used for nectar and 3) the phenology of the emergence of milkweeds. Those investigations were summarized in two entries posted to the Blog:

Nectar plants used by monarchs during March in Texas
https://monarchwatch.org/blog/2021/05/25/nectar-plants-used-by-monarchs-during-march-in-texas/

Monarchs and the freeze in Texas
https://monarchwatch.org/blog/2021/06/01/monarchs-and-the-freeze-in-texas/

Overall, monarchs seemed to find enough nectar and milkweeds to get the breeding season underway. The next question was where most of the eggs were laid by returning females and would that egg-laying lead to the production of a small, medium or large number of first-generation offspring. Although some of the returning monarch moved north before the appearance of milkweeds, my sense, based on numerous reports from mid to north Texas, was that the majority of eggs were laid in these regions. While the distribution of eggs looked favorable, the larvae still have to reach the adult stage and those first-generation offspring then have to recolonize the breeding areas to the north.

To assess the size of the first generation and success of the recolonization, I rely on the first sightings posted to Journey North. The number of first sightings grows from year to year as more people post their sightings. Nevertheless, I can still get a sense of the year- to-year differences based on the timing of the sightings and their number. To assess what has happened this year from late April to early June, I examined the Journey North first sightings maps from 2010-2021. Tentatively, it looks like the recolonization of the summer breeding range this year is the best ever. I say “tentatively” because I have to look at the data more closely. But it does look like this will be a good year for monarchs.

As of late June, it looks like the recolonization could produce an overwintering population ranging from 2-6 hectares with a real potential to be on the high end of that range. To be at the high end of the range, temperature and rainfall have to be within +/-1.5 degrees and +/-2 inches of the long-term means from now through September. While this prediction holds for most of the range, it is particularly important for the conditions to be close to the long-term average for the Upper Midwest, since it is this region that contributes the greatest number of monarchs to the overwintering population.

For more on the influence of environmental conditions on the development of the populations each year, see this recent blog post:

Monarch population crash in 2013
https://monarchwatch.org/blog/2021/06/11/monarch-population-crash-in-2013/

WESTERN MONARCHS
This spring, Monarch Watch announced a partnership with a California nursery to facilitate distribution of native milkweeds. Californians stepped up and we are currently out of milkweeds for the state but will make an announcement when availability returns. If you are interested in donating native milkweed seed to this cause, please see the “Collect Milkweed Seed for Monarch Watch” item below. Thank you!

Google is taking steps to help address the threat facing California’s monarch butterflies:
Doing our part for California’s monarch butterflies
https://blog.google/outreach-initiatives/sustainability/monarch-butterflies-california/

Review published in Conservation Science and Practice:
Are eastern and western monarch butterflies distinct populations?
A review of evidence for ecological, phenotypic, and genetic differentiation and implications for conservation
Micah G. Freedman, Jacobus C. de Roode, Matthew L. Forister, Marcus R. Kronforst, Amanda A. Pierce, Cheryl B. Schultz, Orley R. Taylor, Elizabeth E. Crone
https://conbio.onlinelibrary.wiley.com/doi/10.1111/csp2.432

From the abstract:
In this review, we focus on phenotypic and genetic differentiation between eastern and western monarchs, with the goal of informing researchers and policy-makers who are interested in monarch conservation. Eastern and western monarchs occupy distinct environments and show some evidence for phenotypic differentiation, particularly for migration-associated traits, though population genetic and genomic studies suggest that they are indistinguishable from one another.

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2. Monarch Watch Tagging Kits for 2021
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Monarch tagging continues to be an important tool to help us understand the monarch migration and annual cycle – a long-term record is crucial to understand the dynamics of such complex natural phenomena. Tags for the 2021 fall tagging season are available and we will start shipping preorders out later this month, ahead of the migration in your area. If you would like to tag monarchs this year, please order your tags soon as they are going fast! Tagging Kits ordered after July 21st should arrive within 7–10 days but priority will be given to preorders and areas that will experience the migration first.

Monarch Watch Tagging Kits are only shipped to areas east of the Rocky Mountains. Each tagging kit includes a set of specially manufactured monarch butterfly tags (you specify quantity), a data sheet, tagging instructions, and additional monarch / migration information. Tagging Kits for the 2021 season start at only $15 and include your choice of 25, 50, 100, 200, or 500 tags.

2021 datasheets and instructions will also available online soon via the Monarch Tagging Program page at https://monarchwatch.org/tagging

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3. Submitting Tag Data
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Thousands of you have submitted your 2020 season tag data to us by mail or via our online submission form – thank you! We are still receiving data sheets and if you haven’t submitted your data yet (for 2020 or even previous years) it is not too late. Please review the “Submitting Your Tagging Data” information on the tagging program page then send us your data via the Tagging Data Submission Form.

There you can upload your data sheets as an Excel or other spreadsheet file (PREFERRED; download a template file from https://monarchwatch.org/tagging) or a PDF/image file (scan or photo).

If you have any questions about getting your data to us, please feel free to drop Jim a line anytime via JLOVETT@KU.EDU

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4. Tagging Wild and Reared Monarchs
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As a reminder, the following is an abbreviated version of our “Tagging wild and reared monarchs: Best practices” article posted to our Blog in 2019. The complete text of the article is available via the link below.

Diving into the tagging data has revealed a number of surprises such as the difference between the probability that a reared monarch will reach Mexico and the probability that a wild–tagged monarch will do so. The recovery rate is higher for wild–caught monarchs (0.9% vs 0.5%) and it is the data from the wild–caught butterflies that tell us the most about the migration. Frankly, for some analyses, we have to set the reared monarch data aside. That doesn’t mean it is not valuable, but its uses are limited.

It should be noted that for tagging data purposes, monarchs captured as adult butterflies should be reported as WILD and adult monarchs reared from the egg, larva, or pupa stage should be considered REARED.

TAGGING WILD-CAUGHT MONARCHS
For wild-caught monarchs we need to:
1. increase the number of taggers from western Minnesota and Iowa westward into Nebraska and the Dakotas to give us a more complete understanding of dynamics of the migration;

2. increase the number of wild monarchs that are tagged since these provide the most valuable data; and

3. increase the number of taggers who tag from the beginning of the tagging season in early August until the migration ends. Tagging records for the entire season will help us establish the proportion of the late–season monarchs that reach the overwintering sites. When tagging wild–caught monarchs, many taggers run out of tags well before the season ends. That’s great, but it would help us to know when all tags had been used by indicating this via the online tagging data submission form.

TAGGING REARED MONARCHS
Reared butterflies tend to average smaller than wild migrants. That difference can be reduced significantly if careful attention is given to rearing larvae under the best possible conditions. Large monarchs have the best chance of reaching Mexico, surviving the winter and reproducing in Texas. There are several reasons for this: better glide ratio, better lift with cross or quartering winds, larger fat bodies, more resistance to stress, etc. There are very few small monarchs among those that return in the spring. For those of you who prefer to rear, tag and release, we have a few suggestions:

1. Rear larvae under the most natural conditions possible.

2. Provide an abundance of living or fresh-picked and sanitized foliage to larvae.

3. Provide clean rearing conditions.

4. Plan the rearing so that the newly-emerged monarchs can be tagged early in the migratory season (10 days before to 10 days after the expected date of arrival of the leading edge of the migration in your area).

5. Tag the butterflies once the wings have hardened and release them the day after emergence if possible.

6. When it comes to tagging, tag only the largest and most-fit monarchs (see complete article for some guidelines). Records of tags applied to monarchs that have little chance of reaching Mexico add to the mass of tagging data, but do not help us learn which monarchs reach Mexico – unless the measurements, weight and condition of every monarch tagged and released is recorded. There are a few taggers who keep such detailed records and those data can be very informative. If you collect such data and are willing to share it please contact us; do not add this information to the standard tagging data sheet.

As a final note, this text is not a directive. We are not telling you what to do; rather, we are simply providing suggestions that may lead to more successful rearing and tagging efforts. The expanded version of this article is available at

Tagging wild and reared monarchs: Best practices – https://monarchwatch.org/blog/tagging-best-practices

Have you created a habitat for monarchs and other wildlife? If so, help support our conservation efforts by registering your habitat as an official Monarch Waystation today!

https://monarchwatch.org/waystations

As of 5 July 2021, there have been 34,848 Monarch Waystation habitats registered with Monarch Watch! Texas holds the #1 spot with 2,866 habitats and Illinois (2,695), Michigan (2,572), California (2,255), Ohio (1,803), Florida (1,762), Virginia (1,572), Wisconsin (1,535), Pennsylvania (1,524) and Ontario (1,134) round out the top ten.

You can view the complete listing and a map of approximate locations via https://monarchwatch.org/waystations/registry

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6. Collect Milkweed Seed for Monarch Watch
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Monarch Watch continues to distribute milkweed plugs throughout the monarch range for critical habitat restoration. Please consider donating milkweed seed from wild populations for our partner nurseries to propagate.

Monarch Watch sometimes receives seed donations that perish on the way or in storage. We all want the seed to arrive alive and well-labeled, so please visit the website and read our specific instructions about collecting and donating.

Seed Collecting & Donating Guidelines:
https://monarchwatch.org/bring-back-the-monarchs/milkweed/seed-collecting/

Some areas from which we never seem to have enough of the following seed:

A. tuberosa (butterfly milkweed) from throughout its range, especially Georgia.
A. incarnata (swamp milkweed) from the eastern U.S. states.
A. asperula (antelopehorn milkweed), A. viridis (green antelopehorn milkweed) and A. oenotheroides (zizotes milkweed) from Texas.

Additionally, we need this seed from Arizona and California:

A. angustifolia (arizona milkweed) from Arizona
A. californica (california milkweed) from California
A. eriocarpa (wolly pod milkweed) from California
A. erosa (desert milkweed) from California
A. speciosa (showy milkweed) from California

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7. Monarch Calendar Project
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For those of you participating in our Monarch Calendar project for 2021 (complete details and short registration form at https://monarchwatch.org/calendar/), observation Period 1 has ended (the final date being June 20th, for those of you north of 35N). Once you have logged all of your observations using whatever format works for you (spreadsheet, notebook, calendar, etc.), please use the appropriate online form to submit your data to us:

2021 Period 1 Submission Forms:

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SOUTH (latitude less than 35N)
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Form for Period 1 (15 March – 30 April): https://forms.gle/4imRF4UoVa7TZSnC6

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NORTH (latitude greater than 35N)
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Form for Period 1 (1 April – 20 June): https://forms.gle/KDhVfq5W5duT73vD6

The second observation period runs from 15 July–20 August in the North and 1 August–25 September in the South. As soon as the fall period ends for all locations we will send out links for submission of that data to all who have registered.

Again, complete details and a link to the short registration form are available at https://monarchwatch.org/calendar

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8. Upcoming Monarch Watch Events
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We are tentatively planning to host our annual fall events this year with some changes to the Fall Open House (it will be a shorter outdoor-only event). The tagging has always been an outdoor event so should be similar to previous years. If you’ll be in the Lawrence, Kansas area in September, we’d love for you to join us so mark your calendars and stay tuned to our website, emails and social media for additional details next month.

Monarch Watch Fall Open House (Free event)
EVENT CANCELED
Lawrence, Kansas

Monarch Watch Tagging Event (Free event)
Saturday, September 18, 2021
Baker Wetlands Discovery Center
Lawrence, Kansas

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9. Monarch Rearing, Tagging and Releasing Survey
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In the middle of Covid-19 last June, we conducted a survey of those who rear, tag and release monarchs. Life has been interrupted in many ways over the past year, and we are just now getting around to summarizing the responses (see link below). The number of people who responded (N=1165) exceeded our expectations, and their responses probably represent a good sampling of the reasons people engage in rearing and their rearing practices. Thank you to everyone who participated in our survey!

Monarch rearing, tagging and releasing survey
https://monarchwatch.org/blog/2021/07/06/monarch-rearing-tagging-and-releasing-survey/

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10. About This Monarch Watch List
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Monarch Watch (https://monarchwatch.org) is a nonprofit education, conservation, and research program affiliated with the Kansas Biological Survey & Center for Ecological Research at the University of Kansas. The program strives to provide the public with information about the biology of monarch butterflies, their spectacular migration, and how to use monarchs to further science education in primary and secondary schools. Monarch Watch engages in research on monarch migration biology and monarch population dynamics to better understand how to conserve the monarch migration and also promotes the protection of monarch habitats throughout North America.

If you have any questions about this email or any of our programs, please feel free to contact us anytime.

Thank you for your continued interest and support!

Jim Lovett
Monarch Watch
https://monarchwatch.org

If you would like to receive periodic email updates from Monarch Watch, you may SUBSCRIBE via https://monarchwatch.org/subscribe

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Monarch rearing, tagging and releasing survey

6 July 2021 | Author: Chip Taylor

INTRODUCTION

In the middle of Covid-19 last June, we conducted a survey of those who rear, tag and release monarchs. Life has been interrupted in many ways over the past year, and we are just now getting around to summarizing the responses. While we were targeting those who rear and tag, many people who simply rear and release monarchs responded as well, and we are thankful for those responses. We assured everyone that their information would not be shared and that we wished to simply understand how rearing was being conducted. The number of people who responded (N=1165) exceeded our expectations, and their responses probably represent a good sampling of the reasons people engage in rearing and their rearing practices. As explained below, one of our intentions of the survey was to identify best practices for rearing and releasing. Unfortunately, the survey doesn’t provide the kind of data needed to establish best practices. What it does tell us is that tagged monarchs reared under a broad range of conditions have been recovered in Mexico. It also tells us that while the majority of people who rear, tag and release have not had recoveries, some 20.2% (159/787) reported success. We had hoped that sorting through the conditions reported for those who were successful would help us identify best practices. It doesn’t. There are too many variables which may include things we don’t know about the conditions that lead to diapause and then sensitivity to environmental changes that result in migratory behavior. To sort out the conditions associated with rearing and migratory success, we would have to know the numbers tagged, the dates and locations of release as well as more information about the instars collected or started and rearing methods. We will get those answers in time. In the meantime, we can make some general observations about what needs to be done to rear hardy and healthy monarchs.

Reasons for this survey

As most of you know, Monarch Watch was founded as a monarch tagging program in 1992. At that time, we promoted the tagging of wild caught monarchs, and for a number of years we assumed that our volunteers were only tagging monarchs caught at flowers or collected at overnight roosts. Late in the 1990s, it became clear that some people were tagging monarchs they had reared. At that time, we didn’t pay much attention since rearing and tagging seemed to be a small proportion of all tagging. However, by 2003 it was evident that many more people were beginning to rear, tag and release monarchs. While we didn’t know whether such practices would influence the recovery rate, we decided to be safe, that is, to be able to sort the wild from the reared when analyzing the data. So, we asked participants to indicate on their data sheets, starting in 2004, whether the monarchs they tagged were wild or reared.

Perhaps inspired by the publicity about the decline in monarch numbers and/or the petition to declare the monarch a threatened species, the creation of numerous Facebook sites dedicated to monarchs and other factors, the number of reared, tagged and released monarchs has outnumbered those that are wild caught and tagged for the last several years. Although the tagging records indicate that thousands of reared, tagged and released monarchs arrive at the overwintering sites in Mexico and survive through the winter, it is also clear that the likelihood of reaching Mexico is lower for reared monarchs. We want to know why. We need to sort out why some people who rear, tag and release have much higher recovery rates than others. So, we would like to determine how monarchs have been reared and whether tagged monarchs have been recovered in Mexico.

One reason for the survey has to do with the results in three widely cited studies that proport to show that reared monarchs do not orient properly or are too small or weak to reach Mexico (Davis et al, 2020, Tenger-Trolander, et al 2019, Tenger-Trolander and Kronforst, 2020). While those results may apply to some reared monarchs, it clearly doesn’t explain why almost 2000 reared, tagged and released monarchs have been recovered in Mexico. However, in support of the points raised in these papers, it is clear that the rate of success of reared monarchs in reaching Mexico is much lower than that of wild tagged monarchs. Given that some reared monarchs may lack the ability of orient and migrate, and others may simply be less fit to make the migration, why are many reared monarchs successful in reaching Mexico? It appears that it is easier to fail than to succeed. Although we do not promote rearing and tagging, it seems likely this practice will continue. Assuming this to be the case, we need to understand the reasons for success and failure in order to help those who are engaged in this practice. The survey is the first step in developing a set of standard operating procedures (sops) for rearing that improve the chance that reared monarchs will reach Mexico and will successfully survive the winter. In the end, our objective is NOT to tell people what to do but to provide them with information that will improve the hardiness, health and overall fitness of the butterflies they rear.

Results of the survey

Although 1165 people responded to the survey, because the questions did not apply to all respondents, many of the questions lacked as many answers. Some questions allowed us to assign percentages to the responses. Others did not because two or more of the responses applied or what appeared at the outset to be one question was actually two.

DISCUSSION

As I indicated in the introduction, we expected that we would be able to identify best practices based on the recovery of reared monarchs in Mexico. Specifically, we expected higher recoveries for monarchs reared outside on potted or growing plants that were caged in some way to protect from predators. Next, we expected some success with monarchs reared in cages on porches or other facilities that were exposed to natural temperatures and light. We even expected some success by those who reared monarchs indoors but with an exposure to natural light through windows. What we didn’t expect were reports of recoveries in Mexico by 5 respondents who reared monarchs in rooms without natural light most or all the time. Three of them reared monarchs in rooms with no windows. For monarchs reared in windowless rooms to succeed in entering diapause and then migrating to Mexico is striking. This result is unexpected since it is contrary to studies showing that shortening daylength is required to enter diapause. Further, there were no obvious differences in the number of recoveries of those who reared their monarchs outdoors vs indoors. There were 15 respondents that indicated their rearing was conducted indoors without access to natural light. We need to learn more about these rearing conditions. Since recoveries involve variables, such as point of origin, date of release and numbers released, we will need to dig further into the tagging and recovery data to explain the relationships between rearing conditions and recoveries.

Indoor conditions
Our question dealing with indoor temperatures wasn’t targeted very well and the responses weren’t sufficiently helpful. Observations of the conditions in both the field and lab suggest that diapause induction occurs best when there are distinct differences between day and nighttime temperatures. Night time lows are usually in the 60s, often in the 50s, with mean temperatures of less than 80F. Constant temperatures in the high 70s appear to be too high for diapause induction meaning that the butterflies become reproductive. It follows, that monarchs reared under these conditions would not migrate. More work is surely needed on the factors that lead to both diapause induction and those that lead to reproduction.

Motivation
The motivations of those who rear monarchs were pretty clear. Rearing monarchs is fun, interesting and a bit challenging, and many appear to be motivated to rescue monarch eggs and larvae that would likely be consumed by predators or parasitized by flies. This idea of monarch rescue has resonated and is clearly hard for many to resist. After all, what harm could there be in rescuing a monarch larva from certain death in the mouthparts of a wasp of assassin bug? For many, monarch rescue also means that this practice can contribute to the monarch population, and this goes along with a general interest in monarch conservation. Overall, it’s a powerful combination, something that is fun, combined with the satisfaction of rescuing vulnerable immatures with the notion of adding to the population in a way that contributes to the conservation of the species. Educating children and adults wasalso cited as motivations for rearing. Interestingly, rearing monarchs to tag them was the lowest driver on the list.

Affiliation
Most rearing was conducted at homes (76%) or at a combination of home, school, business and other (11%) with the remaining 13% reared at schools, nature centers and businesses.

Season
Most rearing was conducted in the summer and fall although there were also reports of rearing being conducted in the spring.

Source of eggs and larvae
We were interested in the sources of eggs and larvae used in the rearing since there were some concerns that people were buying stock from commercial breeders that might have been less fit to migrate. However, the responses show that most of the immatures were obtained on their property or nearby properties with only 10 indicating they had purchased eggs.

Female egg layers
We asked a question about obtaining eggs from wild mated females or obtaining eggs from females that were mated to captive bred males. Our curiosity in this case was based on assertions by critics of rearing that inbreeding was involved that would be detrimental to the population. In this case, there were only 18 responses indicating that reared monarchs were allowed to breed and produce eggs. Whether inbreeding occurs under these conditions would depend on the genetic relatedness of the pairings. In the case of brother x sister mating, it could be high, but if the males and females are unrelated, the pairings would be no different from that of wild males and females.

Indoor conditions
Most of the indoor rearing is conducted at room temperature with exposure to natural light through a window. However, there were 15 who indicated that the rearing was conducted in a space with no exposure to natural light. As mentioned above, 5 of these respondents indicated that monarchs reared under these conditions were recovered in Mexico.

Lighting
Most who rear monarchs indoors did not use light timers to increase the photoperiod.

Shelter conditions
This question was really two questions – what type of shelters were used and what were the physical conditions. The only useful information in this case is that most respondents used natural temperatures and light.

Sanitation, washing leaves, fresh food, types of foliage used, crowding and changing practices
These questions were intended to provide some insights about the rearing process. We wanted to know how often rearing containers were cleaned, whether the leaves were washed, how often new foliage was provided, the type of foliage used, how many larvae were being reared together and whether people were changing their practices from time to time to improve their efficiency and success at rearing the larvae to the adult stage. The responses to these questions indicate that most people engaged in rearing have adopted sanitation, feeding and crowding practices that, if followed closely, will lead to the production of healthy monarchs.

Milkweeds
When asked what species of milkweeds were used to feed larvae, there were lots of answers since the use of milkweeds often depends on what is available. Still, there was a clear hierarchy that probably reflects the fact that the majority of those who rear are located in the northeast. Most frequently used was common, followed by swamp, and tropical milkweeds. Of the top 3 used, tropical only accounted for about 11% of the responses.

O. e. questions (Ophryocystis elektroscirrha)
We asked a number of questions about O.e. to determine how those rearing monarchs were dealing with this disease. The sanitation questions fit here as well since washing leaves in particular could eliminate many if not all of the O.e. spores from the leaf surfaces. Still, over 88% of the respondents did not test for O. e. or work with Monarch Health, an O.e. monitoring program directed by Sonia Altizer at the University of Georgia. There were fewer responses to the question about whether monarchs with O. e. were released, but of those, 61% said they did not. We also asked whether monarchs with O. e. were euthanized. This question is similar to asking if monarch with O.e. were released. The answer to the euthanize question generated 635 responses with 72% affirming that they euthanized monarchs with O. e.

Drying time
Because monarchs use most of the first day to mature and are not fully flight capable and therefore vulnerable to predation by wasps, dragon flies and some birds, we asked whether monarchs were released the first day or later. The answers indicated that only about 20% of the respondents routinely allowed monarchs to mature before releasing them. Another 42% indicated that the day of release varied.

Weigh and measure
Since forewing length and overall fitness are related to migratory success, we wondered how many people were aware of this and whether they made the effort to measure forewing length and weigh the monarchs before releasing them. As expected, the majority did not, yet 13 respondents indicated they did weigh monarchs, and 41 said they measured wing length. This question is related to tagging questions regarding whether all or only some reared monarchs are tagged and released.

Tagging
When we asked whether respondents tagged the monarchs they reared, a surprising 32% said no, they only rear to release monarchs locally. Since we were targeting those who rear and tag and didn’t really solicit responses from those who only rear and release, it seems likely that the proportion of those who only rear and release is larger than indicated in this survey. While most of the tagging was conducted during the recommended time framessome 7% indicated they tagged at other times. When we asked if only large monarchs or all monarchs were released, a surprising 14% indicated that they only tagged large monarchs. In the future, we can specify what is meant by large, but since most people were not measuring monarchs or aware of the size issue, we chose not to do so.

Recoveries
There were two questions on recoveries. One asked whether the respondents had recoveries, and the other asked the recovery rate – that is, the percent of all those tagged and released that had been recovered. Surprisingly, 22% reported recoveries and 20 indicated that their recovery rates were 1% or higher. Those are good numbers, typical of those, mostly in the Midwest, who have been tagging wild monarchs for many years.

CONCLUSIONS

The main conclusion we can draw from this survey is that the results, while in some ways robust, are insufficient. These results have failed to indicate that there is a standard or at least a better way to rear monarchs to assure migratory success. In fact, there are no clear trends in the rearing methods and, if anything, they indicate that monarchs reared under a great variety of conditions, including rooms without windows, are capable of entering diapause and successfully migrating to Mexico. An explanation, or at least a partial explanation, of the variability of the success in reaching Mexico may lie in the preconditioning 5th instar larvae experienced outdoors before they were brought into rearing rooms. To determine if this was the case, we compared the recovery rates for those who only reared wild collected 5th instars (N=17) with those who reared small larvae (N=68). The recovery rates were 29% and 19% respectively. Again, not much of a difference from the overall mean of 20.2% with the possibility that the lower % for those rearing small larvae was due to the greater percentage being reared in the East vs the Midwest. Unfortunately, our survey was too general, with many sample sizes that were too small, to pick up on details such as these. Additional information is needed about the rearing conditions, and the age of the larvae, in all cases with recoveries, and we need to know more about the size and mass of those tagged. Further, more experimentation is needed to determine the conditions that lead to the induction of diapause and migratory behavior. We also need to establish the temperatures that block diapause induction or lead to the breakdown of diapause once monarchs begin migrating.

In spite of the limitations of the survey, we can pass along a few observations from the tagging results that bear on migratory success. Analysis of tagged wild and reared monarchs shows that success in reaching Mexico is a function of the site of origin and the date of release. Monarchs released late in the migration and from more distant locations are less successful in reaching Mexico. Further, a number of studies have indicated that large monarchs dominate the leading edge of the migration and apparently have the highest probability of reaching Mexico. Rearing last generation monarchs outdoors on caged rooted or potted plants seems most likely to produce monarchs that enter diapause and migrate. Of course, care should be taken not to expose host plants to egg laying females to prevent O.e. spores from contaminating the leaves. The alternative is to sanitize the rooted or potted plants before using them as food for developing larvae.

REFERENCES

Davis, A. K., Smith, F. M. and A. M. Ballew. 2020. A poor substitute for the real thing: captive-reared monarch butterflies are weaker, paler and have less elongated wings than wild migrants. Biol. Lett.16 20190922.

Tenger-Trolander, A., Lu, W., Noyes, M. and M. R. Kronforst, 2019. Contemporary loss of migration in monarch butterflies. PNAS July 16, 2019 116 (29) 14671-14676

Tenger-Trolander, A. and M. R. Kronforst, 2020. Migration behaviour of commercial monarchs reared outdoors and wild-derived monarchs reared indoors Proc. R. Soc. B.28720201326

TABLES