Monarch Watch Update - October 2006



1) Status of the Population

2) Pollinator Stamps and Pollinator Week

3) Rate of Habitat Loss and Monarch Waystations

4) Breeding Cages

5) Arkansas Monarchs

6) About Monarch Watch


Unless otherwise noted, all content was authored by Chip Taylor, edited by Jim Lovett, and Ann Ryan and published by Jim Lovett.


1) Status of the Population

The month of October was so eventful that I have an abundance of topics to deal with in this Update; too many in fact. I’ll save some of the less time sensitive topics for the November-December Update.

Briefly, here is a recap. On the 2rd of October the NYTimes Science Times published a story on the tagging sponsored by Monarch Watch and the Jayhawk Audubon society at the Haskell-Baker wetlands on the 16th of September:

New York Times Article

The article resulted in a flood of emails containing first hand accounts of sightings of massive numbers of monarchs from Maine to Long Island and claims from experienced observers in Massachusetts that the migration this year was the best in the last thirty or forty years. Other emails reported monarchs at sea during the fall migration. A comment I made during the interview with Donald McNeil, the reporter from the NYTimes, that monarchs reaching the coast were “toast” led to an extensive series of exchanges on Dplex-L on the nature of the tagging and tag recovery data. (I will deal with this discussion in the next Update). At the same time, an extraordinary concentration of monarchs was spotted in SE Arkansas. This excitement was followed in about two days by numerous observations of one of the largest monarch migrations reported through central Texas in many years. In addition, there were numerous other topics that surfaced during the month.

Size of the migratory population

One of the unusual features of the migration this year was the concentration of the major flight. In most years, as the monarchs pass any one point on the way south, it takes about 6 weeks for the migration to pass. Further, there is a period of 10-14 days in the middle of the migration at each location during which large numbers pass through the area. In other words, the migration usually has a long passage and a fairly broad peak. This pattern applied to eastern Kansas and the east coast this year but by the time monarchs reached central Texas, they were highly concentrated and the main portion of the population appeared to pass through a given point in three days. This appeared to be true of central Texas, e.g., Austin, San Antonio, south Texas, Eagle Pass, and Queretaro (Mexico). The descriptions of the masses of monarchs passing through a region are often quite graphic and the numbers described are beyond the ability of the observers to estimate. Nevertheless, because most of the observations originate from one or a few scattered locations, in spite of massive numbers observed, it is difficult to judge the size of the entire population. In the September Update, I estimated that the overwintering population would be about 6.5 hectares or roughly 325 million butterflies. What should we see when this many butterflies pass through central and south Texas? How wide and deep (high) is the river of butterflies moving through this region? It would seem that the river would have to be a hundred or so miles in width with butterflies passing from near ground to 1200 or more feet in altitude, weather conditions permitting. The possibility of documenting such a passage from the ground, even with a large number of observers, seems remote. NEXRAD radar might be able to detect the monarch migration. However, special settings would be required to detect butterflies and these settings would be low priority since the principal applications for these systems are air traffic control and weather monitoring. The bottom line is, even though I have some misgivings based on the rapid passage of the population as described above, I’m still sticking to my estimate of an overwintering population of 6.5 hectares.

Rate of movement of the migration

The dates of tagging for all butterflies, and the dates on which recovered butterflies were tagged, both indicate that the monarch migration is quite predictable. This statement doesn’t preclude the fact that almost every year some monarchs are sighted ahead and others behind the expected time of passage around the country. Nevertheless, it does give rise to statements and misstatements, some of which I’ve generated, about the rate of passage of the migration. Analysis of the tagging data indicates that the AVERAGE rate at which the leading edge of the migration advances is approximately 26 miles per day. But what of the individual butterflies, do they maintain this pace? The best way to determine the AVERAGE rate of progress for individual monarchs comes from those cases in which a live tagged butterfly is sighted among newly arrived monarchs. Because most recovery data is from dead butterflies, the number of cases in which both the day of tagging and day of arrival are both known precisely is small. We had one such case this fall. Harlen Aschen found a newly arrived male monarch near Port Lavaca, Texas on 3 November. The butterfly, (BIZ277), was tagged on 9/23/06, in Whitehouse, OH 43571, by Duke Wheeler. The interval from tagging to sighting was 40 days and Harlen, evidently using the web site “How Far Is It”, declared the straight-line distance to be 1,146 miles (with an initial heading of 223 degrees). If all the information on this butterfly is correct, his AVERAGE rate of movement over the 40 days was 28.6 miles per day. Each year produces 4-6 similar records. Analysis of these records is yet another project for which I have to find a student. An image of this butterfly can be found on Harlen’s web site at

I received a note from Harlen on the 7th of November indicating that this butterfly was among 1000 monarchs that were raised and released at the annual Monarch Release at the Butterfly House in Whitehouse, Ohio (


2) Pollinator Stamps and Pollinator Week

If you have created a Monarch Waystation, in addition to creating a habitat for monarchs, you have created resources for numerous other pollinators. Creating habitats for pollinators is also vital. On the 18th of October, the National Academy of Sciences and National Research Council released a report (Status of Pollinators in North America) describing the decline in the availability of honey bees for the pollination of crops and the state of our knowledge of other pollinators, many of whom also seem to be declining. A brief synopsis of this report can be downloaded at: The diversity of our plant communities is highly dependent on the pollination services of a wide variety of pollinators. The North American Pollinator Protection Campaign (NAPPC) is dedicated to not only drawing attention to the plight of pollinators but to promoting their conservation. To this end, this organization has formed numerous alliances designed to protect pollinators and the habitats that they both service and depend upon. To learn more about NAPPC please visit: and

This remarkable organization now lists over 90 institutional partners and its influence is growing. Monarch Watch is one of the participating partners in NAPPC and I have been a member of the Steering Committee for this organization since its inception in 2001. Three years ago NAPPC began to lobby the United States Postal Service for the creation of a postal stamp recognizing the importance of pollinators. The US Postal Service receives 50,000 suggestions for postal stamps ideas each year but, through a process known only to a few, the idea of a pollinator stamp gained support with the result that a beautiful 4 stamp set will be issued during National Pollinator Week: June 24-30, 2007. The support by congress of National Pollinator Week is another of NAPPC’s achievements. The following is a link to the press release issued by the postal Service for the pollinator stamps:


3) Rate of Habitat Loss and Monarch Waystations

Loss of habitat is often cited as the greatest threat to the populations of animals and plants. Habitat losses are usually attributed to human activities such as deforestation and other forms of conversion of natural landscapes to human centered use. Most of the arable land in the US has already been converted into farmland. In fact, the total acreage of farmland in the US has been declining since the late 1940s. The present rate of development is an astonishing 6000 acres per day (4 acres/minute)! It’s hard for most of us to comprehend how big an area 6000 acres represents. There are 640 acres per square mile so the loss of 6000 acres equals the loss of habitats in an area of 9.37 square miles! I live in Lawrence, Kansas, a town with a footprint of about 12 square miles and 88,000 people, so the development of 9.37 square miles is like creating a town 78% the size of Lawrence each day. On a yearly basis the loss of habitat is 2.2 million acres. At this pace, in another 18 years, we will have paved over and otherwise destroyed habitats for wildlife in excess of the area of our 25th largest state, Illinois. That’s a lot of habitat to loose and populations of wildlife including monarchs are certain to decline. As individuals, most of us are not in a position to create habitats or protect wildlife. However, we can all do something to create, conserve and protect monarch habitats. For example, we can:

1) support organizations, such as Monarch Watch, that promote monarch conservation,

2) create Monarch Waystations in our gardens and promote the creation of these habitats in gardens at schools, nature centers, city parks and businesses. Further, we can encourage the restoration of milkweeds on private and public lands and along roadsides.

3) protect existing monarch habitats wherever possible through education and wise management.

4) discourage the use of herbicides on public lands in favor of strategic mowing.

5) educate our fellow citizens as well as local and national decisions makers about the threats to wildlife and monarchs.

There are more than 1,000 registered Monarch Waystations - that’s a good start but it isn’t enough. Given that we are losing 6000 acres a day to development, monarchs need many, many, many, more Waystations.

One of the wonderful things about Monarch Waystations is that they award you. The monarchs will come but you will get to enjoy an abundance of other wildlife as well. Many of the stewards of Waystations rear the monarch larvae found in their gardens and share them with schools, nature centers and their neighbors. Others take joy in just rearing and releasing the monarchs. One participant in the program reared and released over 600 monarchs last summer! That’s making good use of a small habitat. I once tried to calculate the average per acre production of monarchs for the entire breeding area that contributed to the fall migration and came up with estimates of .3 to 1.5 monarchs per acre. What this means is that a Waystation with a good patch of milkweed that produces fall monarchs can contribute as many monarchs to the population as a much larger patch of land. Let’s create those habitats folks. They do make a difference.


4) Breeding Cages

We often receive questions about the construction of the cages we use for breeding monarchs. Our largest cage is 4’wx4’hx8’l. One of our standard cages is 22" square and these worked well for studies of comparative mating when we had the white (nivosus) stock. One of our cages works well for a single pair matings and for egg laying by isolated females. It's quite small.

The cage consists of a tube of acetate only 7 inches in dia. To make the cage, cut a piece of acetate into a strip 6" or more in width and overlap and staple the ends together so as to make a 7" diameter cylinder. Stable a strip of wire window screen to the lower end of the acetate cylinder. Now you have a tube with acetate on the top and screen on the bottom.

There are four other pieces. An 8" flower pot, a clear plastic lid, from a pie container obtained from your favorite bakery, a 6 oz cup or other container that holds water for the cut oviposition/nectar plants and a circular piece of 3/4 inch plywood cut to fit into the 8" pot so it rests where the pot is constricted about 1.5 inches from the top. The plywood has two cuts in it; a 3.5 diameter recessed hole 1/4 inch deep, this is for the cup that holds the scrubber and the artificial nectar and a 3/4" hole drilled through the plywood. This hole provides an opening to insert the nectar and/or host plant into the water containing cup below. The recessed cut keeps the feeder from sliding and spilling when moving the cages.

If space is limited, the cage is ideal since it only stands 14" high (although one could make it higher) and is only 8" wide. When assembled, the cage contains a feeder and host or nectar plants and a monarch pair or an already mated female. Adult monarchs and host plants are easily removed from these cages. The productivity of individual females can be tracked easily with this system.


5) Arkansas Monarchs

Several times each year I’m reminded of how little I know about monarchs and how much there is to learn. I’ve been following the fall monarch migration intimately through the eyes of Monarch Watchers all over the country for the last 15 years. Much of the information about the migration gleaned from all of you, and the public, is pretty much the same from year to year, However, now and then we receive a report about monarchs that has us scratching our heads. Such an event occurred this fall in SE Arkansas with the discovery of 100,000 -160,000 monarchs clustered for most of a week in a hedgerow adjacent to a large weedy field. The event was remarkable for five reasons: 1) the large number of fall migrants in one place 2) the apparent duration of the monarch’s use of one location 3) the mass (weight) of these butterflies, 4) the size distribution of the wing lengths and 5) the conditions under which they departed. Before I get into all these “Oh, my!” details I’ll summarize what I’ve been able to learn of this “event”.

On the 10th of October I received an email from a colleague, Alberto Broce at Kansas State University, of a large concentration of monarchs in SE Arkansas. The email in question referred me to a Carl Jeffers of Portland, Arkansas. I called Carl and spoke some time with him and with his wife Vivian. Our discussion revealed that the Jeffers had discovered a field of goldenrods that was covered with monarchs. It was not just a field but 1000 acres of CRP land (conservation set-aside) in which the monarchs numbered in the thousands. The text of the email read "hundreds of thousands" of monarchs on a 10 acre field of goldenrods. The density is at least 100 monarchs per square meter." Given the email statement about 10 acres, I asked Vivian three times about the size of the area and she assured me each time that it was a thousand acres. When I asked about the estimate of the number of monarchs, Vivian told me that their best guess is that 40-50 thousand monarchs were using the area at one time. (Actually, Carl and Vivian had tried to contact us directly by email but their report was lost among the hundreds of reports we receive during the migration).

The monarchs were discovered on Saturday the 7th and Vivian and Carl made trips to the location each morning and evening. Vivian gave this description of the exodus from the field each evening. About 6:15 the monarchs begin to leave the flowers and head for the hedgerows. Movement of the butterflies toward the trees accelerates by 6:30 and by 6:45 there is a virtual cloud of monarchs seeking places to roost in the trees - so much so that to observers they look like flocks of birds coming to roost. By 7PM all but a few of the monarchs are at rest in the trees.

The site is located in SE Arkansas across the river and about 20 miles from Greenville, Mississippi. The location is 10.2 miles due east of Wilmot, AR on state highway 52, specifically,T19SR3W Section 10, and 33o04'00"N, 91o24'00"W. The Google Earth image provided by Jim Edson shows the general location. The east-west hedgerow is shown as a dark horizontal line in the middle of the second image.

Dr. Jim Edson, a long time Monarch Watcher, from nearby Monticello, Arkansas learned of the monarch concentration and drove to the area on the 11th. Jim was the source of additional information on the location and on the size and mass of the butterflies. In a phone conversation, Jim reported that a wildlife biologist in the area, who is familiar with assessment techniques, estimated that the number of monarchs in the tree line was 100,000 to 160,000. The tree line runs E-W with two large fields of goldenrod to the north and south. The fields have been in CRP for 5-6 yrs and are now planted with hardwood seedlings.

Jim drove to the Arkansas site again on the morning of the 13th. He was well prepared with cameras and other gear but discovered upon his arrival at 8AM that the monarchs of the 11th were gone. He did manage to get a few compass readings on the flight directions taken by the few remaining monarchs before the wind picked up. Most were heading about 60 degrees west of south or +/-240 degrees.

Jim weighed a number of the monarchs on the 12th and a few more on the 13th. Some of the monarchs were so "fat" they could barely fly and Jim was astonished to find that many weighed between .6-.9 grams! Most of the monarchs we see in KS weigh .4-.6 grams with mean weights just above .5 grams. I have never seen a monarch that weighed more than .7 grams so these were indeed quite engorged. Some of the monarchs that lingered at the site on the 12th weighed in at the more traditional .4 -.5 gram range.

Subsequently, Jim sent us some of the monarchs collected by the Jeffers on the morning of the 12th. We weighed and measured these butterflies and they were indeed the heaviest monarchs we have ever seen with many weighing .7-.9 grams. A monarch weighing .7 grams is extremely rare in Kansas so to see these monarchs with strikingly robust, even bloated, abdomens was amazing. The sample was also unusual in that variation in wing length was quite low. The number of small individuals, i.e. those with wings measuring 44-49 mm, was much lower than typically seen in samples from this latitude.

I asked Jim to collect samples of the plants being visited by the monarchs and to have them identified if he could. The curator of the herbarium, Eric Sundell, at the University of Arkansas at Monticello identified the two major plants being used as nectar sources by the monarchs as:

1. Solidago canadensis – a widely distributed goldenrod species and an excellent fall nectar source for bees and butterflies.

2. Aster pilosus – a fall aster sometimes called white heath aster. This plant is also one of the best end of the season nectar sources for a variety of pollinators including butterflies.

Both of these species are among the first to colonize areas in which the soil has been disturbed. So, it follows that they are abundant in an area that was prepared for tree planting some 5-6 years earlier.

David Moyers, a reporter for a regional newspaper, the Ashley County Ledger, interviewed Jim and wrote an account of the monarch aggregation that can still be found at;

As mentioned above, this was an unusual event for a number of reasons.

1) This was the largest concentration of monarchs observed in one place for at least 6 years.

2) That such a large concentration of monarchs stayed in one place for 5-6 days is also unusual. Monarchs may arrive in the 10’s of thousands late in an afternoon but the mass of them usually dwindles over the next few days such that after 5 days the numbers are much reduced and clustering is less evident. It may have been that butterflies were continuing to both leave and arrive over the observation period but the engorgement suggests that many of the butterflies may have lingered most of this time period.

3) The distended abdomens of these butterflies were unmistakable and unusual. Not only did many of the butterflies weigh .7-.9 grams but the average mass for the sample was higher than for any similar sample of monarchs I’m aware of in the United States.

4) Measurements of wing lengths showed that the sample was composed predominantly of mid sized to large monarchs. Small monarchs in the range of 46-49 mm were noticeably underrepresented in the sample. The puzzle is what happened to the small monarchs?

5) The butterflies left the area en mass under unusual conditions. The 12th of October was a cold to cool fall day for SE Arkansas and I didn’t expect the butterflies to leave yet they were all but gone when Jim Edson arrived at 8AM on the 13th. So, what were the conditions on the 12th and what might have caused the monarchs to leave the nectar fields and the hedgerow?

The weather conditions for the 12th of October from the nearest weather station at Greenville, MS are given at:

Looking at this record, my guess is that the monarchs left the hedgerow shortly after the ambient temperature reached 57F (around 10:30). If they departed in the late morning or early afternoon, they left the area under mostly cloudy to overcast conditions with the tail winds from the NNE to NE of 15mph. Monarchs often leave en masse when the winds become favorable as they did in this case. What strikes me as unusual is the temperature of 57F. This temperature is close to the minimum temperature, usually considered to be 55F, for sustained flight by monarchs.

In one of his messages, Jim Edson mentioned that he learned from some hunters, who had a camp nearby, that monarchs visited this area in large numbers each fall. Obviously, this is an area to watch closely next year.

I wish to thank Vivian and Carl Jeffers for drawing the monarch communities’ attention to this spectacular concentration of monarchs and to Jim Edson for his on site investigation and collaboration.


6) About Monarch Watch

Monarch Watch is a not-for-profit educational outreach program based at the University of Kansas. We manage several educational, conservation and research programs - focusing on the monarch butterfly, its habitat and the spectacular fall monarch migration.

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 800-444-4201 (KU Endowment Association) for more information about giving to Monarch Watch.

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