Monarch Watch Blog

Monarch Population Status

20 August 2012 | Author: Chip Taylor

In early July I wrote the text for the pre-migration newsletter that goes out with the tagging kits in which I stated that there was no real basis for making a prediction about the size of the fall migratory population:

“If there is sufficient rainfall and normal to above normal temperatures in the northern breeding range through August, the migratory population may be the largest since 2003 – perhaps 6-7 hectares. On the other hand, a continuation of the extreme heat and drought conditions could result in another overwintering population in the 2-3 hectare range – well below the long-term average of 7 hectares.”

It is now clear that fall population will be on the low side with an overwintering population close to 3 hectares once again. I don’t need to tell you that the summer was hot and dry – too hot and dry in many areas for good monarch reproduction. We have received many comments on the poor quality of the milkweed available to monarchs for the last generation. In eastern Kansas, where the drought ranges from extreme to exceptional, milkweeds, even blue vine (Cynanchum laeve), suitable for egg laying, are scarce. The best areas for the production of fall migrants appear to be northwest and central Minnesota, northern Wisconsin and Michigan, and much of New England. Reports from New England suggest that the number of monarchs passing through Cape May will be higher than normal this fall. Elsewhere, we can expect the number of fall migrants to be similar to that seen over the last several years.

The low number of nectar sources that will be available to monarchs moving through the lower Midwest in September is a concern. Some fall flowers have already bloomed, some have died and many of the others are stunted and just barely alive. There will be nectar but it will be harder for the monarchs to find. Rain in the areas of Nebraska, Kansas, Oklahoma, Missouri, Iowa, Arkansas, and Illinois over the next three weeks could make a big difference in the proportion of the fall migrants that reach Mexico.

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Monarch Tagging Kits

20 August 2012 | Author: Jim

Tags for the 2012 fall tagging season are still available but going fast – more than 75% of this year’s tags have been claimed to date. If you would to tag monarchs this year, please order your tags as soon as possible.

Monarch Watch 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. Tagging Kits for the 2012 season start at only $15 and include your choice of 25, 50, 100, 200, 300, or 500 tags.

Monarch Watch Tagging Kits and other materials (don’t forget to pick up a butterfly net!) are available via the Monarch Watch Shop online at – where each purchase helps support Monarch Watch.

Datasheets and instructions for the 2012 season are also available online at

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Monarch Population Status

30 July 2012 | Author: Chip Taylor

A year like no other…

There has been no year in the 117 years of climate records for the United States that matches what we have all experienced in the last 12 months. We have been tracking how monarchs are affected by climate for a number of years and there have been obvious patterns, like cooler March temperatures in Texas are associated with larger overwintering populations in Mexico. Similarly, warmer May temperatures are more favorable since they favor re-colonization of the northern breeding areas. Also, warmer summers in the northern breeding range are better for monarch production.

This year, however, is off the charts. March was the warmest recorded in Texas – not a good start based on past records. May was also warm, allowing monarchs to move into the northern breeding areas earlier by two to three weeks and in numbers that were unprecedented. Early arrival in the north in the past has been associated with population declines but in those years the average summer temperatures were in the normal range. This summer is starting out to be different from other summers with June temperatures exceeding the norm over most of the northern breeding area. What will happen this year with early arrivals followed by a warm summer, possibly one of the hottest summers ever recorded?

Not only has it been warm, it’s been hot and dry – perhaps too hot and dry for good monarch reproduction. And, then there are the milkweeds and nectar plants to consider. Plants grew rapidly this spring with many species blooming 10-30 days earlier than normal. Plants that typically flower in the fall began blooming in June and reports continue of water stressed plants blooming early. Milkweeds were no exception with flowering being earlier almost everywhere, raising the question as to what their condition they will be in the last week of July and the first week of August when most of the eggs are laid that produce the migratory generation cialis. If the milkweeds are past their prime, and are senescing, will this diminish the size of the last generation?

There are also questions as to whether large numbers of monarchs overshot (that is, flew beyond) the limits of milkweed. Unprecedented numbers of monarchs have been reported from the Prairie Provinces of Canada where milkweeds are scarce, from the Maritime Provinces where monarchs are usually few, and even from Newfoundland, an area with virtually no milkweed. As you can see, there are many questions but little basis for making a prediction as to the size of the fall migration. If there is sufficient rainfall and normal to above normal temperatures (+/-80F) in the northern breeding area through August, the migratory population may be the largest since 2003 – perhaps 6-7 hectares. On the other hand, a continuation of the extreme heat and drought conditions, a track that seems equally likely, could result in another overwintering population in the 2-3 hectare range – well below the long-term average of 7 hectares.

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Monarch Population Status

12 June 2012 | Author: Jim

What a spring it’s been – the warmest in 117 years of record keeping and the warmest 12 months ever recorded in the United States. In response to the warm conditions the plants and insects have made early appearances. Some plants bloomed 6 weeks early, others a more modest 2 weeks. Most insects appear to have kept pace including monarchs that arrived 2-3 weeks early over most of the northern breeding range – raising the possibility of a large fall migration – maybe the last big migration this decade.

Climatologists are telling us that hotter summers with strong droughts are ahead and that won’t be good for monarchs. Habitat decline will continue as well so, let’s tag while we can. We have ordered tags for the 2012 tagging season and the orders are coming in rapidly. If you would to tag this fall, please order your tags early. If your fellow monarch enthusiasts see a large migration shaping up, we are likely to be out of tags by the 1st of September. Please place your order now so as not to be disappointed.

Monarch Watch 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. Tagging Kits for the 2012 season start at only $15 and include your choice of 25, 50, 100, 200, 300, or 500 tags.

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

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Tag Recovery Database Updated

30 May 2012 | Author: Jim Lovett

The Monarch Watch Tag Recovery Database ( has been updated – more than 16, 000 records now, in a searchable format. Check to see if any of your tags were recovered in Mexico this year 🙂

Tip: to generate a list of all tags reported to us this year, simply select 2012 from the “Year” dropdown menu in the “Recovery Information” section and hit the “Submit” button.

recovery database search

Thanks to all of you who have participated in the tagging program and to those who have contributed to the tag recovery fund. These contributions are needed since we compensate the ejido members in Mexico who search for the tags among the dead butterflies beneath the colonies. And, thanks to many people who helped acquire the tags in Mexico in our – and your – behalf.

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First Monarch Butterfly of the Year

9 April 2012 | Author: Chip Taylor

Margarete Johnson spotted a monarch butterfly yesterday (8 April) while gardening in Monarch Waystation #1 here at Monarch Watch (Lawrence, KS).

Margarete beat me by a day.

This morning I spotted a faded female monarch while walking the dog in western Douglas County, KS (6 miles east of Berryton, KS).

My earliest sighting over the years occurred on the 7th of April – an event that was followed by an April storm that took out the roof of our greenhouse and froze all manner of early bloom or leafyness and no doubt that early monarch.

The extended forecast through the 3rd of May indicates that overnight temperatures will be above normal for 23/24 days. There is no frost in sight and our last frost was on the 9th of March (the mean day of last frost for this area is 15 April). The season is off to an unusual start, one that should benefit monarchs and butterflies in general – at least in eastern KS. We are already seeing numerous butterfly species that originate from TX. Yesterday, the flow of red admirals through this area was quite exceptional. I have already seen more swallowtails than I saw all of last year. We just need about an inch of rain a week to keep things on track…

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Monarch Population Status

19 March 2012 | Author: Chip Taylor

The size of the overwintering monarch population in Mexico is usually released in late January or February. Early reporting helps all of us plan for the season ahead. Unfortunately, for reasons that are not clear, this report wasn’t released to the press until the 15th of March – at the end of the season and a week after the first monarchs from Mexico had made their appearance in Texas. The total for all colonies, as reported to the press, is 2.89 hectares. There is good news and bad news in this number. The good news is that the population was larger, by almost a hectare, than I expected. The bad news is that this number represents the 4th lowest total for the monarch colonies recorded since the winter of 1994-1995. Further, this population represents a continuation of a trend – the 8th consecutive population below the long term average.

The figure below represents the total number of hectares of monarchs at the overwintering sites in Mexico from 1994 through the winter of 2011-2012*. Two averages are indicated – the long-term average that incorporates measures for all years (X=6.99) and an average for 2004 to present (x=4.16).

Overwintering Area Figure

It is apparent that there has been a significant decline in the overwintering monarch population since 2003. This decline is related to the adoption of herbicide tolerant row crops that were first introduced in 1996. As pointed out in previous communications, the milkweeds in these row crops were shown in 2000 to produce more monarchs per unit area than other monarch habitats. By 2004 the adoption of corn and soybeans genetically modified to resist glyphosate exceeded 51%. The adoption rate by 2010 was 81% (see figure**). Milkweeds are now scarce in this formerly productive habitat. Overall, the amount of habitat lost due to the adoption of these crops may exceed 100 million acres.

Overwintering Figure

These losses combined with the annual loss of habitat of 2 million acres, the overuse of herbicides and mowing, the reduction of conservation reserve program (CRP) acreage and the increasing conversion of pastures and grasslands to corn and soybeans for the production of biofuels point to a continuing decline in monarch numbers in the years ahead.

As I say in the header of our website: “To assure a future for monarchs, conservation and restoration of milkweeds needs to become a national priority.”

The question I’m wrestling with is: how can we make this happen? How can the monarch community engage and inform the public and the decision makers of the necessity of restoring milkweeds to save the monarch migration. Our Monarch Waystation and the Bring Back the Monarchs programs, or their facsimile, need to be broadly adopted. We need a national campaign to restore habitats for monarchs.

* The areas of the monarch overwintering colonies are measured several times during the winter. Because the sizes of the colonies increase as the season progresses from mid November to mid December and vary with temperatures, the areas obtained in mid December, a period with relatively low temperatures and little flight, are used to represent the population. Over the period from 1994 to the present, the assessment of colony sizes has been conducted by two organizations, the Monarch Butterfly Biosphere Reserve (MBBR) and World Wildlife Fund Mexico (WWFM). The MBBR teams were led by Eligio Garcia Serrano. Since 2004, Eduardo Rendon has led the monitoring teams supported by WWFM cialis. The monitoring by these teams over the years is much appreciated. Without their hard work our understanding of the factors that determine monarch numbers from year to year would be poor indeed.

** Thanks to Janis Lentz for creating this figure.

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Monarch Population Status

22 November 2011 | Author: Jim

In the last update of the eastern monarch population (late September) we noted that it would be interesting to see how monarchs cope with the lack of nectar and water in Texas. We knew that the migration would make it through Texas (and Northern Mexico) but we didn’t know what impact the drought conditions would have on it.

Modest numbers of monarchs have already arrived at the overwintering sites in Mexico and they will continue to arrive through the end of the month. Preliminary reports indicate that the monarchs are spread out over an area of four hectares or so at this time but we expect this area to shrink in the coming weeks as the masses of monarchs become more consolidated.

Our predictions regarding the size of the overwintering monarch population still stand (visit the link above for details); official measurements will be done in late December and we will report the findings in an update after the first of the year.

Stay tuned!

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Monarch Population Status

22 September 2011 | Author: Chip Taylor

The following is a brief update on the status of the eastern monarch population.

The leading edge of the migration has now reached northern Texas. As many of you know, we attempt to follow the monarch population closely. Based on our experience, and ongoing data analysis of monarch numbers, we offer opinions/projections on what to expect in the near future based on our understanding of how the monarch populations have been affected by patterns of temperature and rainfall in the preceding months.

Late in the spring I started predicting a small migration this fall. In the Premigration Newsletter sent out with the Monarch Watch Tagging Kits, I predicted that overwintering population in Mexico would be similar in size to that of the low populations recorded in 2004 (2.19 hectares) and 2009 (1.92 hectares). It was clear that the monarch numbers in New England and recorded at Cape May would be low this fall, and that the numbers originating in the central region would be slightly better than those of the eastern Dakotas through Wisconsin but still low relative to long term numbers. The New England/Cape May projection appears to be correct as the numbers are down in this region. I was wrong about the central region (Ontario, MI, OH, IN, IL) – fewer monarchs appear to have been produced in this area than I expected. Wisconsin numbers also appear to be down.

The surprise is the eastern Dakotas and western MN. This area seems to be the source of a large number of the monarchs moving through the lower midwest at this time. Nevertheless, the overall numbers are down. But, it gets worse. The migration is just beginning to navigate a 1000 miles of hell – a nearly flowerless/nectarless and waterless expanse of central KS, OK, TX, and NE MX (see Drought Monitor).

Drought Monitor - 20 September 2011

It is too late for rains to change the situation in TX and northern MX. Monarchs will make it to the overwintering sites but their numbers will be significantly reduced by these conditions. My expectation is that that the overwintering numbers will be the lowest ever (previous low 1.92 hectares) and that the arriving butterflies will be in relatively poor shape with low fat reserves. If the average condition (mass) of the overwintering monarchs is lower than average, mortality during the winter could also be high. Other scenarios could include low returning numbers next spring with a reduced reproductive capacity due to low fat reserves. Keep your fingers crossed that there are no winter storms in MX that could make matters worse.

It will be interesting to see how monarchs cope with the lack of nectar and water as they move through TX. Monarchs, like most insects, have hygroreceptors (sense organs that are sensitive to humidity gradients); therefore, when conditions are extremely dry, we might expect monarchs to seek out the darkest and most humid habitats. If this plays out, most monarchs will accumulate in drainages, along rivers, move in an out of forests, and concentrate around other water sources.

As I pointed out in the Premigration Newsletter (and the August Population Status blog article), there is a new reality, or expectation, regarding the size of the overwintering population in MX. It now appears that winter populations will be in the range of 2-6 hectares (down from the long term average of 7.24) with 6 hectares being reached only during the most favorable conditions. In the near term, the average overwintering population will be close to 3 hectares. As we pointed out recently (Brower et al. 2011), the decline is related to the loss of habitat, particularly the rapid adoption of herbicide tolerant (HT) crops. The majority of these crops are planted within the summer (June-August) breeding area for the monarch population. In spite of weed control methods prior to 1996, when HT crops were first introduced, milkweed persisted in these croplands at a low level where they provided an excellent resource for monarchs. With the planting of HT engineered corn and soy followed by the use of glyphosate to control weeds, milkweed has been almost completely eliminated from these crops. At present, the total area of HT crops is larger than that of any state except TX and AK, or about 4 times the state of IL). The decline in the monarch population first became noticeable in 2004 when the percentage of HT corn and soy acreage exceeded 50% of all acreage for these crops.

Low monarch numbers in MX this winter and in the future means that the integrity of the overwintering sites is now more important than ever and that planting milkweeds in gardens and incorporating these plants in restoration projects either as seeds or plugs should receive the highest priority.

Monarch Waystations – Create, Conserve, & Protect Monarch Habitats

Bring Back The Monarchs – It’s not too late…

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Chip in for Monarch Watch 2011

2 August 2011 | Author: Jim Lovett

Monarch Watch is turning 20 and needs your help! If you are in a position to offer financial support to Monarch Watch (or if you know someone who might be), please consider making a fully tax-deductible donation of any amount during our 2011 “Chip in for Monarch Watch” fundraising campaign.

It is no secret that Monarch Watch founder and director Chip Taylor is passionate about monarchs and Monarch Watch – he is genuinely concerned about the future of the monarch migration and that of our program as well. In honor of Chip we officially launched in 2009 the now annual “Chip in for Monarch Watch” fundraising campaign – 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 two decades ago.

Last year’s campaign was a huge success, raising $23,000 via nearly 500 donors – wow!

We encourage you to spend a little time reading through previous donor comments – the connections that are facilitated by monarchs and Monarch Watch are truly extraordinary.

Complete campaign details at:

Thank you for your continued support!

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