Monarch Watch Blog

Monarch Watch Update February 2023

Saturday, February 11th, 2023 at 10:00 am by Jim Lovett
Filed under Email Updates | Comments Off on Monarch Watch Update February 2023

This newsletter was recently 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 form at

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. Overwintering Monarchs at El Rosario
3. Monarch Watch Tag Recoveries
4. International Western Monarch Summit
5. Milkweed Programs & Milkweed Market
6. Wanted: Gerber Baby Food Tubs
7. About This Monarch Watch List

1. Monarch Watch One-Day Fundraising Event

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 secure our future and support our mission to sustain the monarch migration – donations of any amount do help and are greatly appreciated.

On Thursday, February 16th 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 program.

This year, you may choose to support:

1) the Chip and Toni Taylor Professorship in Support of Monarch Watch to help us secure the future of Monarch Watch by hiring a new professor/scientist/director (more info at ), or

2) the Monarch Watch Fund to help us continue to expand our education, conservation and research programs and aid many people in their efforts to create habitats to sustain the monarch migration.

During the one-day event, gifts to the Chip and Toni Taylor Professorship in support of Monarch Watch will be matched dollar for dollar, up to $50,000, through a generous Director’s match. Additionally, thousands of companies match gifts to higher education institutions, which can double or even triple the impact of your contribution. To find out if your employer has a matching gift program, please visit

To make a contribution to Monarch Watch online the day of the event, visit and 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 during the “One Day. One KU.” event.

No matter how you give, KU Endowment will allocate 100% of your gift to the fund you choose, and gifts are tax-deductible within the limitations of U.S. federal income tax laws. For Canadian donors: Please note that the Canadian government will not permit you to declare online donations to us as a tax-deductible donation and a check must be mailed instead (see info at

Don’t forget to check your email next Thursday, February 16th for the reminder and link – thank you!

2. Overwintering Monarchs at El Rosario

The days are getting longer, and temperatures are increasing in the northern hemisphere. The decline in activities imposed on nearly all insects by cold conditions is beginning to reverse. For monarchs, that means more flight typified by streaming downslope to seeps and areas where the grasses are covered by dew. They need water to metabolize the lipids acquired during the migration into a sugar named trehalose that provides the energy needed to power all bodily functions. As the temperatures increase, monarchs also become more sexually active with mating increasing dramatically after the 12th of February when the angle of the sun above the horizon at noon drops below 57 degrees. This connection with the solar angle at solar noon (SASN) may be coincidental or not, but there is a connection with both the start of the migration and its end. In the vicinity of Winnipeg at 50N, the migration begins in the first week of August when the SASN value drops below 57 degrees. Further, the first monarchs arrive in the vicinity of the overwintering sites in the last few days of October when the SASN value drops below 57. Celestial changes may also be associated with the declining increase in day length as first-generation monarchs colonize the summer breeding areas. For discussions on this topic see the “Monarch Puzzle Wrap Up” article at

As to mating, a study by Tonya Von Hook (1993) indicated that mating in February was predominantly between small males, that were often in poor condition, and large females. While that raised questions about whether small males might be selecting large females as mates based on their prospective ability to lay large numbers of eggs, there are several other things that we should be thinking about. First, why is it that small males are engaging in sexual activity and larger males are less engaged in courtship behavior? Next, are the small males actually selecting for size or are they only able to mate with the larger females? Also, is there any reason large females would choose to mate with small males? And if small males are not discriminating but are attempting to mate with all females, what does that say about these dynamics? Lastly, what if there is no selection by either sex? Could that explain the outcomes?

Maybe it comes down to one word – maneuverability. The small males and females could be more maneuverable with the result that small females are more often able to escape the attentions of small males than large females. Problem solved, but what about those small males, why are they sexually active sooner than larger males? Again, one word – hormones, specifically juvenile hormone (JH) produced by a gland in the head known as the corpora alata. JH production leads to the development and maturation of reproductive tissues, and it could be that small males simply produce more of this hormone early in the season or that all males produce similar amounts, but that JH activates sexual activity faster in the small males due to their small mass and lower lipid content. Since it is possible, perhaps evenly likely, that small males wouldn’t survive the return migration to Texas, there is a tendency to attribute this behavior to a recognition on the part of these males that it’s now or never. If so, we would be talking about cognition and that would be asking a lot for an organism with a mass of less than half a gram and very small brain. So, I don’t think so. It’s just hormones.

While those activities represent what a portion of the overwintering monarchs are doing, the majority, and especially those deep within the forest, are settled on limbs and tree trunks as shown in the pictures below. These photos were taken by Estela Romero on visits to the monarch colony at El Rosario in the first week of February and last week of January 2023.

Van Hook T. 1993. Non-random Mating in Monarch Butterflies Overwintering in Mexico. Pages 49-60 in Malcolm SB, Zalucki MP, eds. Biology and Conservation of the Monarch Butterfly. Los Angeles, USA: Natural History Museum of Los Angeles County.

3. Monarch Watch Tag Recoveries

Many of you have been asking about when tag recoveries for the 2022 tagging season will be posted online. The tag recoveries within the U.S., Canada and northern Mexico were recently posted online via; recoveries from the overwintering sites in central Mexico are typically reported to us in March and posted online in April once everything is received and verified. We will make an announcement via our email updates so stay tuned!

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

4. International Western Monarch Summit

–Chip Taylor, Director, Monarch Watch, University of Kansas

There is a growing movement in the West to sustain the Western monarch population. Efforts are underway in all states west of the divide (except Montana and Wyoming) to provide data that can be used to understand why this population varies from year to year and what can be done to assure there will be monarchs in the future. These efforts are led by Robert Coffan who has been aided by a dedicated group of supporters. The first Western Summit was held in January 2020 and the second in San Luis Obispo in January 2023. I was invited to speak at both events.

In the first, I stumbled through an attempt to bring what I knew about the dynamics of the eastern population to the West. Looking back, there were both good and naïve approaches to understanding monarch numbers in the West. I did show that temperatures were increasing and that the effect was leading to a decline in overwintering locations and numbers in the five southern counties. I also created a matrix of monthly means of temperatures and precipitation for all time periods and areas of the West. Colleagues and I have worked that matrix over and over to identify patterns and explanations, but aside from the general increase in temperatures associated with declines, I consider that approach to be a failure.

In the slides linked below, I have taken a deeper dive into the differences in the conditions between the East and West. As you will see, the West is not only more complicated, but there is only one data set to work with – and there are reasons to question how well that data set represents the size of the population, especially in warmer years.

In summary, there are several messages: 1) more data are needed, 2) the year-to-year variation is largely driven by weather and not habitat loss, pesticides or other factors, and 3) in the long term, monarch numbers will be driven by increasing temperatures from September through February in the coastal counties.

You are welcome to share, discuss and question the interpretations on these slides.

Monarch Population Development: A stage-specific model (slides and notes)

5. Milkweed Programs & Milkweed Market

Monarchs Need Milkweed. Monarch caterpillars only eat milkweed, and you can get milkweed plants from Monarch Watch, possibly for free! Just choose the milkweed program that fits your situation.

Free milkweeds for habitat restoration projects

Monarch Watch will once again be distributing free milkweeds for planting in large-scale habitat restoration projects Spring 2023. Since this program began in 2015, over 731,000 milkweeds have been planted in restored habitat throughout much of the monarch breeding range. New this year, we have added several more regions in California. To qualify, applicants must have a minimum of two acres (one acre or less in California) 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:

Free milkweeds for schools and educational non-profits

Schools and educational nonprofits may apply for a free flat of native milkweeds for a public garden or habitat space. Single flats of 32 plants (58 for Texas) will be distributed to recipients in the spring, while milkweed supplies last. The application can be found here:

Milkweed Market

Native milkweeds for gardens or habitat are available for purchase from our Milkweed Market at The minimum purchase is one flat of 32 plants (58 for Texas). If your space is not large enough for 32 milkweeds, share with your neighbors! The market is now open for pre-orders and availability is based on your ZIP code and our supply.

6. Wanted: Gerber Baby Food Tubs

Reduce, Reuse, Recycle! Do you or someone you know use Gerber Baby Food that comes in those small plastic tubs? If you have access to a supply of these empty containers, consider sending them to us (please rinse them first!) for reuse as monarch rearing chambers. I don’t think Gerber had monarchs in mind when they introduced these tubs, but they work quite well and save us a lot of time compared to other methods we’ve used. The 4 oz tubs work best but we can use the 2 oz tubs as well.

Some of you may recall a similar request years ago that showed how we use these tubs – the plastic lids are no longer included but we still have a good supply of those, and they fit the current tubs.

Please start saving these empty tubs for Monarch Watch and once you have a number of them (shouldn’t take long!) please contact us at for mailing/shipping instructions. If you can coordinate a collection from several sources to send in a single package, all the better. Thank You!

7. About This Monarch Watch List

Monarch Watch ( ) 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 or you can simply call 785-832-7386 (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

You are receiving this mail because you were subscribed to the Monarch Watch list via or – if you would rather not receive these periodic email updates from Monarch Watch (or would like to remove an old email address) you may UNSUBSCRIBE via

If you would like to receive periodic email updates from Monarch Watch, you may SUBSCRIBE via

This e-mail may be reproduced, printed, or otherwise redistributed as long as it is provided in full and without any modification. Requests to do otherwise must be approved in writing by Monarch Watch.

Sorry, comments for this entry are closed at this time.