Monarch Population Status

It is the season at Monarch Watch when the mailbox is full of tagging datasheets. Many of the datasheets are arriving with returned tags along with short notes lamenting the lack of monarchs this past fall and requests for an explanation as to why the fall 2008 monarch population was so low.

The lack of monarchs was apparent all through the season and not just in the fall. On July 18th, again at the urging of many concerned Monarch Watchers, I posed my midseason assessment of the status of the population (“Where Are The Monarchs?”). My interpretation at that time was that the conditions during the period from late April to early June, when the first generation monarchs were moving north from the breeding areas in Texas and other southern states, limited the number of monarchs reaching the summer breeding range. Specifically, I said:

May, the moving month for first generation monarchs, was cold – throughout the entire northern breeding range. It was also a period of frequent storms and heavy rains, particularly during the second half of May. Early June also saw heavy rains, especially in the east north central and central portions of the country.” Cold and rain were thought to a) limit dispersal, b) reduce egg laying, and c) increase mortality of adults resulting in a reduction of the potential fecundity of this generation. After assessing all of the factors my conclusion was that “unless you are all missing something out there, the number of reproducing adults over the next three weeks will be low, to be followed by a relatively small migratory generation.

Unfortunately, our collective observations were correct and a relatively small fall population has come to pass.

One issue that I raised in the July assessment was that the number of first generation monarchs coming out of Texas and other areas of the South might have been lower than predicted by temperatures and observations of the numbers of larvae found on milkweeds. Drought, fire ants, herbicides (especially those applied to the milkweed rich pastures in central Texas), and loss of habitat could certainly reduce the numbers of first generation monarchs. The quality and quantity of monarch habitats as well as land management practices need to be assessed for the South. Indeed, we need a national assessment of monarch/milkweed habitats throughout all breeding areas to better understand what needs to be done to conserve the monarch migration. I will be writing more on this topic in the coming months.

As the observations of the migration came in via email, Dplex-L, the Monarch Forums, and other sources, I tried to arrive at a guess as to the size of the overwintering population in Mexico. Based on previous experience it was obvious to me the overwintering population was certain to be less than five hectares. But how much less? The previous models I’ve developed were not too helpful, since we have only seen one other year (1997) when the April-May conditions seemed to limit the summer breeding population. So, I’ve just had to make a flat out guess, albeit one based on my memory of migrations over the last 16 years, and my guess is that the overwintering population will be 3-4 hectares with an expectation that the final number will be closer to the low end of this range.

An early December report in a Mexican newspaper indicated that authorities expected the overwintering population to be 4.8 hectares. However, it was not clear whether this figure reflected actual measurements of the colonies or was an estimate. As you may remember, the overwintering colonies are measured twice in December and it is the measures taken in the second half of the month that are used to calculate the final estimate for the year. Two measures of each colony are taken because many butterflies are on the move early in the month and the colonies are still in the process of consolidating. Once the colonies are well established, cooler weather tends to cause the colonies to contract and the area occupied by monarchs diminishes by 10-20%. So, the expectation of 4.8 hectares reported to Mexican newspapers could well be reduced if it was, in fact, based on early December measures of the colonies.

Tagging Datasheets – a Reminder

If you have not sent in your tagging data sheets, PLEASE DO SO NOW before these data are lost. We will be heading for Mexico later this winter to buy tags. Each year we return having bought many tags without data due to the fact that some of our participants have not returned datasheets. Although most of the money for the recovered tags comes out of my pocket, I’m most concerned about the lost data. Every recovery provides valuable information and you may never learn if the monarchs you, or your group, caught and tagged were recovered in Mexico, so please send us those datasheets! Thank you for your interest and participation in our Monarch Tagging Program.

Monarch Watch Tagging Event

Come visit us this Saturday – in person or online!

Saturday, 20 September 2008 7:30-11:30am CDT
Lawrence, KS, USA

Once again, Jayhawk Audubon Society and Monarch Watch are sponsoring Monarch butterfly tagging for the public at the Baker University Wetlands. The wetlands are located along 31st Street between Haskell and Louisiana. The event will be held from 7:30 AM until 11:30 AM on Saturday, 20 September 2008. There is no charge to participants and no experience is necessary – so bring yourself, your kids (all ages), your friends, and your neighbors! If you have a net, bring that too, though JAS and Monarch Watch will provide the tags, nets, and instructions in how to net and tag monarchs. In 2001, 325 participants tagged nearly 3,000 of the estimated 20,000 Monarchs present, and at least 85 of those tagged were recovered at the winter roost sites in Mexico! You can view all of the recoveries tagged at these events by searching for Lawrence-tagged monarchs in our searchable recovery database.

Every year, tens to hundreds of thousands of Monarchs stop on their way south to refuel on the nectar from the ocean of yellow Bidens flowers at the wetlands, a fantastic site in its own right. We will have check-in and information tables just inside the boardwalk entrance to the wetlands so you can arrive and leave whenever you please. The monarchs are usually roosting or clustering (sometimes in spectacular concentrations!) until around 8:30AM. As it warms up, they begin foraging on the Bidens flowers around the boardwalk.

Complete details are available online at 2008 Monarch Watch Tagging Event – there we plan to feature a live audio/video broadcast and post photos during the event so that everyone that can’t make it can at least see (and hear!) what’s going on. You will also be able to participate in a live chat session with fellow Monarch Watchers.

Monarch Watch Fall Open House – Wow!

Our recent Fall Open House was like no other. We had at least 1,000 people visit Monarch Watch that day (twice the usual number) and we gave out over 450 chrysalids to the children in attendance. The weather was less than ideal – cloudy with occasional rain and not a one of the 200 butterflies in the Biohouse so much as opened their wings but it didn’t seem to matter to our visitors. The garden (Monarch Waystation #1) so carefully nurtured by Margarete Johnson and her colleagues among the Douglas County Master Gardeners, was spectacular. With a little sun the garden would have been filled with butterflies as well as fantastic flowers.

A photo slideshow (50 images) is available online and other details are available at MonarchWatch.org/openhouse

At least one of our visitors blogged about the event – you can read her article and see her photos here: Monarch Watch 2008 Open House

My thanks to all and especially to the Monarch Watch crew, particularly Jim Lovett and Ann Ryan, who made this event possible.

Monarch Watch Fall Open House

Come visit us this Saturday – in person or online! 🙂

Monarch Watch Open House
Saturday, 6 September 2008 8am-3pm

Join us at our Fall Open House at Foley Hall (KU West Campus) on Saturday, September 6th to celebrate the arrival of migrating monarchs coming from the north. This free event is designed to please children and adults alike.

At the Open House you can learn about creating Monarch Waystations and see the magnificent butterfly and pollinator garden created and maintained by Margarete Johnson and the Douglas County Master Gardeners. Weather permitting, you will see an abundance of butterflies and numerous other small but important pollinators. On a good day over 20 species of butterflies visit the garden. The Biohouse, adjacent to the garden, will be filled with monarchs and other species. The Biohouse and garden contain numerous butterfly flowers. Bring your cameras. It is well worth a visit.

As usual, we will provide refreshments, lots of show & tell (including a honey bee observation hive and some “Oh, my!” insects you may have never seen before), tours of our gardens and lab space, hands-on activities, games, videos, monarch tagging demonstrations, iChat videoconferencing, and, of course, lots of monarch caterpillars, pupae, and butterflies!

We will also have a limited number of Monarch pupae (to emerge as a butterfly at home or at school) that will be given to each child in attendance, while supply lasts.

If you can’t be there, be sure to visit us online at the address below to see what we’re doing – we plan on having at least a couple of webcams broadcasting the day’s events.

Again, the Monarch Watch Fall Open House will be at Foley Hall on KU’s West Campus, Lawrence, KS on Saturday, 6 September 2008 8am-3pm. For more information, a map, and directions, visit

For images of some of the butterflies and caterpillars seen at last year’s event see the photo gallery at: www2.ljworld.com/photos/galleries/2007/sep/07/butterflies/

2008 Tags – Going Fast!

The 2008 monarch tagging season is upon us!

Many of you ordered early and have already received your tagging kits – if you haven’t ordered yet there is still time, but the 2008 Monarch Watch Tagging Kits are going fast. If you would like to participate in the 2008 season tagging this fall, please place your order for tags as soon as possible so that you don’t miss out.

Monarch Tagging Kits are only shipped to areas east of the Rocky Mountains.

As usual, each tagging kit includes a set of specially manufactured monarch butterfly tags (you specify quantity), a datasheet, tagging instructions, and additional monarch/migration information. Standard Tagging Kits for the 2008 season start at only $15 and include your choice of 25, 50, 100, 200, 300, or 500 tags. Sets of 20 Mini Tagging Kits (5 tags each) are available for $40 – for Nature Center programs, etc. that would like to distribute a small number of tags to participants.

Tagging Kits and other materials (don’t forget to pick up a butterfly net!) are available via the Monarch Watch Shop online at Shop.MonarchWatch.org

HAPPY TAGGING!

Where are the monarchs??

“Where are the monarchs?” has been a common question asked of us over the last month or so and the following is the best answer I can provide at this time.

Thanks to all of you who have contacted us with your assessments of the status of the monarch population. The vast majority of reports indicate that the monarch population appears to be much lower than normal. Most of these observations have been from areas where the monarchs are between broods and sightings of adults are usually low in early and mid July. So, this aspect of the reports is not alarming. The general absence (or low numbers) of larvae, as indicated in many reports, is of greater concern. The larvae present now mature into adults in late July and early August. These butterflies produce the offspring (from eggs generally laid from the 20th of July to the 10th of August) that become the butterflies that join the fall migration. Again, with few exceptions, unless you are all missing something out there, the number of reproducing adults over the next three weeks will be low, to be followed by a relatively small migratory generation. This assessment could be wrong of course and let’s hope that this is the case.

Assuming our collective assessments are, in fact, correct and that the population is low, how do we account for the lower than expected number of monarchs?

Here is what I know about the monarch population (December 2007 to the present):

1. The overwintering population in Mexico measured 4.61 hectares, a bit lower than the average of about 6 hectares in recent years, but not alarmingly so.

2. Although mortality during the winter was higher than normal at one location on Cerro Pelon, overwintering mortality appeared to be normal at other locations.

3. Examination of monarchs at several colonies at the end of the season showed them to be in remarkable condition with large numbers of nearly immaculate butterflies with large fat bodies. The proportion of monarchs in poor condition appeared to be lower than normal.

4. The migration into Texas appeared to be quite good, although a bit delayed. Some monarchs lingered at the overwintering sites as late as the first week of April. Various observers in Texas reported large numbers of returning adults and others subsequently reported large numbers of larvae on milkweeds in pastures south of Dallas.

5. March temperatures in Texas were neither too hot nor too cold and the simple temperature based model I’m developing suggested at that time that the overwintering population might be as high as 8 hectares. All appeared to be well in Texas and on track to produce a large number of first generation monarchs that could colonize the northern breeding grounds.

6. The first generation monarchs usually pass through Kansas from the last few days of April through the first week of June. During good years, the movement of first generation monarchs through this area can be quite conspicuous with many of the passing monarchs stopping to lay eggs on the blooming milkweeds. There was no obvious “flow” of first generation monarchs through the area this year and relatively few eggs and larvae were found on milkweeds in May and early June.

7. This observation gives rise to two questions: a) was the first generation much smaller than expected? and b) are there other explanations for the relatively low numbers of monarchs that reached the northern breeding grounds? Or, is the explanation some composite of these two possibilities?

8. At this point there is no way to assess the success of the first generation in Texas and other southern states. If the fire ant population was higher than it has been in recent years, predation by these ants could have had an impact. However, I don’t think the ants are widespread or abundant enough to have a large-scale impact on the population. The weather during March and early April in Texas was favorable for reproduction so I’m inclined to look to another cause.

9. May, the moving month for first generation monarchs, was cold – throughout the entire northern breeding range. It was also a period of frequent storms and heavy rains, particularly during the second half of May. Early June also saw heavy rains, especially in the east north central and central portions of the country.

10. In spite of these limiting conditions, bursts of monarchs reached some northern breeding areas, notably Iowa, parts of Ontario, and southern New England.

11. So, how could the May and early June conditions have limited the monarchs? In a few words, by: a) limiting dispersal, b) reducing egg laying, and c) increasing mortality of adults. All together such effects result in a reduction of the potential fecundity of the generation and the “realized fecundity” is lower than expected. The impact of lower temperatures and heavy rains on survival of larvae are unknown but might also have reduced the population.

12. What about the future? The monarchs could surprise us. If temperatures are moderate for the remainder of the summer and a substantial number of eggs are laid from 20 July to 10 August, the population could rebound.

13. As a number of you have pointed out, this year is not a good year for butterflies in general. This means that the parasites and predators that make a living feeding on a broad range of lepidopterous larvae are starving or not reproducing in good numbers. If parasites and predators are low, the result could be that there will be a reduction in the loss of monarch larvae during the last generation giving rise to a larger migratory population that seems to be indicated at this time.

Based on what we know now, my expectation is that the overwintering population in Mexico will be lower than the 4.61 hectares measured last year. As always, I hope my predictions are overly pessimistic.

Spring Open House & Plant Fund Raiser

Everyone is invited to join us this Saturday (May 10th 2008 8am-3pm) for what very well may be our last Spring Open House and Plant Fund Raiser at our current location on KU’s West Campus.

This year’s event will feature activities for children, with the special assistance of Brenda Mott from the Children’s Museum of Kansas City from 11AM-1PM. We will also have live exotic and local insects, videos of monarchs and bees, a honey bee observation hive, and 4,000 continuously blooming butterfly and hummingbird plants you can select from for your garden – and/or as a gift to mom for Mother’s Day. Naturally, we will have lots of milkweed available 🙂

We will also provide refreshments, lots of show & tell, videos and games for children, tours of our garden and lab space, and, of course, monarch butterflies!

We’d love to see you here so mark your calendars! If you’re unable to make it in person, be sure to watch the Blog for photos and updates throughout the day.

Complete information including photos from a past event, directions, and a map is available online at monarchwatch.org/openhouse/

Preliminary List of 2007 Season Recoveries

A preliminary list of Monarch Watch tags retrieved from Mexico last month is now available:

2007 Season Recoveries List

The records are ordered by tag code so that you can easily look for tags you have used. We are in the process of adding them to our Tag Recovery Database and hope to have the complete records online soon.

For further discussion of the recoveries this year, see our “2007 Season Tag Recoveries” posting made earlier this month.

If you have any questions please feel free to drop us a line at monarch@ku.edu

Milkweed and Nectar Plant Phenology Project – Part 3

The University of Kansas issued the following press release last week, calling for fellow Kansans to get involved in our recently announced phenology program.

You don’t have to live in Kansas to participate – we would like to encourage anyone and everyone in the U.S. to join in! This is a great project for classrooms, nature centers, families, and those interested in making additional uses of their Monarch Waystation habitats.

Kansans asked to track climate change in their own backyards

Monarch Watch, a citizen science outreach program at the University of Kansas, invites school children, gardeners and interested citizens to observe and record the growth of 16 common and easily identified plants through the growing season in Kansas.

“With all the talk about climate change, one might suppose that such changes would affect the growth of plants and the first appearances of some birds and mammals,” said Chip Taylor, director of Monarch Watch. “In fact, scientists are just beginning to record seasonal changes in plant and animal life in a systematic manner.”

The study of the seasonal “firsts” such as first robins, first shoots or first flowers is known as phenology. Monarch Watch is collaborating with a nationwide effort headed by the National Phenology Network to record the phenology, or “firsts,” for plants that are important to the success of monarch butterfly populations.

Input from the public will help scientists to distinguish changes that are due to unusual weather patterns from those attributable to long-term climatic changes.

To participate, visit the Monarch Watch blog (“Milkweed and Nectar Plant Phenology Project“) describing “firsts” that require observation.

Next, record the date of the observed “firsts,” such as first flower, in a notebook and submit the data at the National Phenology Network Web site.

“There are only a few scientists and they can’t be everywhere to record the many ‘firsts’ each year,” said Taylor. “That’s why we need citizens to help. We need observers everywhere.”

Monarch Watch is particularly interested in plants such as milkweeds that are hosts for monarch larvae and nectar plants that are visited by adult butterflies to fuel reproduction or migration.

“Studies of the year-to-year differences in the first appearances of these plants will help us understand the yearly differences in the size of the monarch population,” said Taylor.

Other groups are tracking plants important to honey bees.

Earlier plant growth and flowering due to climate change are of increasing interest to scientists. In 2007, March in Kansas was warmer than in any year since 1910 — with the result that in some areas garden plants, crops and native plants were as much as 12 days ahead of normal by April 2. Then came the “big freeze” of April 4-10, with as much as 60 hours of freezing temperatures.

“It was simply too warm too soon,” Taylor said. “The result was devastating for crops and for all plant life in eastern Kansas as well as the wildlife that was dependent on the pollen, nectar, foliage or fruits, nuts and berries that would have been produced.”

This year is cooler than normal — but how much are plants delayed?

“If we can get lots of people to record their observations, we can make sense of these year-to-year changes,” Taylor said. “Participation in this study is quite easy.”

How Does Your Garden Grow? – Part 2

Last month (“How Does Your Garden Grow?“) I outlined my intention to show you how to use our Monarch Watch Temperature Loggers to record the temperatures in your garden and how to use the data to determine the growing degree days required for different plant species, especially milkweeds, to reach particular stages such as first shoots, first flowers, etc.

The temperatures for the winter (December-February) and March for Monarch Waystation #1 and for Lawrence are shown in Tables 1 and 2.

Table 1. Winter and March temperatures (2007-08) for Monarch Waystation #1, Lawrence, KS.

Table 2. Official winter and March temperatures (2007-08) for Lawrence, KS.

As I noted last month, the garden is both warmer and colder than the official weather station for Lawrence. Nevertheless, the mean temperatures are similar. How these differences will translate into growing degree days remains to be seen.

The mean temperature for Lawrence for March was 41F, quite a bit cooler than the average of 46.3F recorded from 1971-2000. In Kansas, the mean temperature for March (1895-2007) was 42.6F degrees and the temperatures this year are much lower than for 2007 in which the mean temperature was 52.2F, second only to the 54.7F recorded in 1910. As you may recall, due to the high temperatures, plant growth was advanced by as much as 12 days last spring leading to disastrous consequences when the jet stream, with temperatures in the teens, dipped into the lower Midwest and swept into the Southeast. In many areas there were 60 or more hours of freezing temperatures resulting in crop losses from Kansas to South Carolina (Figure 1). Fortunately such events are rare and less likely in years such as this one since temperatures through March have delayed plant growth to some degree.

Figure 1. Cold wave of 4-10 April 2007.

From NOAA/NESDIS/NCDC

A sample of the data from one of the data loggers in our garden is shown in Figure 2.

Figure 2. Temperatures recorded for the first 12 hours of 2 March 2008 (data logger #1).

To record the number of degree days (DD) these data have to be imported into a Degree Day Workbook. The workbook calculates the DDs for each hour and summarizes the total number of monarch degree days for each day and for each month. The DD output for the first 6 days of March 2008 for Monarch Waystation #1 is shown in Figure 2. The Degree Day Workbook now found in the Monarch Watch Forums is in the process of being modified so that you can enter data for each month of the year. You will also be able to specify if you wish to calculate the degree days for either monarchs or plants. The methods are the same but the ranges of temperatures over which growth occurs are different for plants and monarchs.

Figure 2. Temperatures and monarch degree days for the first 6 days in March 2008.

There are two things to note about Figure 2: 1) the number of DDs is zero if the temperatures for the entire day are either above or below the developmental thresholds for the monarchs or plants and 2) the most important data is the accumulated DDs (Acc. DD) in the last column.

Assuming there are no freezing temperatures during the period of measurement, the number of degree days required for each of the monarchs’ life stages is: egg 45C/113F, larva 187C/369F, and pupa 120C/248F or about 720F for each generation (egg to egg). For a further discussion of degree days please see “Degree Days and Monarch Growing Season“