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).

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.

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.

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* 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 Lovett

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).

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: monarchwatch.org/chip

Thank you for your continued support!

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Monarch Population Status

2 August 2011 | Author: Chip Taylor

Monarch Watch turns 20! We started our monarch tagging program in September of 1992 – it doesn’t seem that long ago but I guess that we have been so busy that we lost track of the passing years. We began by recruiting our first taggers through notices in newspapers that called for volunteers and sending out tagging kits as fast as we could put them together. The response by the public was overwhelming and the positive feedback from the participants led to the creation of Monarch Watch, an organization we didn’t envision at the outset.

We started tagging in a down year for monarchs but we didn’t realize it then. Only later did we recognize that the dust veil created by the eruption of Mount Pinatubo had led to a significant reduction in summer temperatures and monarch numbers as well. A lot has happened since 1992. We’ve seen the overwintering population in Mexico increase each year from 1994 to 1996, only to crash inexplicably in 1997. We have seen ups and downs in overwintering numbers – but mostly downs since 2003. In fact, the population has been below the long-term average over the last seven years. Ominously, the four lowest populations recorded to date occurred in the last 11 years. The downward trend is now statistically significant (Brower, et al. 2011) and it is clear that we have entered a new era of monarch numbers.

The great migrations of the 90s are a thing of the past. In the future, we can expect overwintering populations in Mexico of 2-6 hectares. The main reason for the decline is loss of habitat. Monarch habitat has been reduced by at least 140 million acres in the last 10 years – about a fifth of the total breeding area available to monarchs has been lost. At least 100 million acres of habitat has been lost due to the adoption of herbicide resistant corn and soybeans. The herbicide tolerant (HT) crops allow growers to spray their crops with herbicides without affecting the crops. The result has been the near elimination of milkweeds in these row crops and a reduction in monarch numbers – monarch production in these fields was higher when measured in 2000 than in roadsides, old fields, conservation reserve lands and other habitats (Oberhauser, et al PNAS 2001). The adoption of HT crops began slowly in 1996 but has been increasing rapidly since 2003. By 2010 80.7% of the corn and soybeans planted in the United States (161 million acres) were herbicide tolerant. Since these crops are used in rotation, it is likely that milkweeds have been eliminated in more than 81% of the total acreage.

So, where does this leave us and what does this mean for tagging? It means that we will have another year like the last seven and a year not unlike 1992 when we started the program. Specifically, we can expect a low year, perhaps not as low as 2009 (1.92 hectares) or 2004 (2.19 hectares) but close to these numbers. The migration should be particularly low in the New England area and the numbers at Cape May will be low as well. The central region (Ontario, MI, OH, IN, IL) will see a modest migration and could produce more monarchs than the area defined by the eastern Dakotas, MN, WI, and IA. Even though the population will be down from historical highs, there will still be plenty of monarchs to tag. And, as always, you and your fellow taggers will not only have fun but you will also contribute to our knowledge of the monarch migration.

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Monarch Tagging Kits for 2011

31 July 2011 | Author: Jim Lovett

Our tags for the 2011 Monarch Watch Tagging Kits arrived recently and we sent out the first batch of kits on Friday. Those of you that ordered between January 1st and June 30th of this year should receive your tags within the next few days.

If you haven’t ordered your tagging kits yet, there is still plenty of time before the migration begins – but the tags are going fast. If you would like to participate in monarch tagging this fall, please place your order for tags as soon as possible so that you don’t miss out.

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 2011 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 Shop.MonarchWatch.org

HAPPY TAGGING!

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NYTimes: In Midwest, Flutters May Be Far Fewer

12 July 2011 | Author: Jim Lovett

Today’s printed New York Times features “In Midwest, Flutters May Be Far Fewer” – an article by Andrew Pollack about monarch habitat loss and population decline. Monarch Watch Director Chip Taylor is quoted, along with other monarch researchers.

Many Monarch Watchers found this article online yesterday and commented about the featured photo – one of a Gulf Fritillary rather than a monarch. The photo has since been replaced with that of a monarch butterfly and the entire article is available online. Please take a moment to read it and then pass it on!

NYTimes.com: In Midwest, Flutters May Be Far Fewer

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Another Honeybee Swarm (video)

6 June 2011 | Author: Jim Lovett

Another swarm of several thousand honeybees settled in a bait hive outside of Monarch Watch HQ on June 6, 2011…

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Monarch Population Status

26 April 2011 | Author: Chip Taylor

I’ve been monitoring the reports of returning monarchs quite closely this spring. The pattern of the return this year is similar to that seen in 2006 but more exaggerated, with more monarchs moving into the mid latitudes (35-42N) than in any previous April (see Journey North’s first sighting reports). As I pointed out last spring on our email discussion list and in a text written for our May 2006 email update, such early arrivals at more northerly latitudes are not necessarily a good thing. If these butterflies arrive when the milkweeds are above ground and abundant followed by temperatures that allow for normal development of eggs, larvae and pupae – all is well. But, all isn’t well this year. Monarchs arrived in our area (38.97N) in good numbers on the 10th of April with egg laying noted from the 10th through the 15th with some additional eggs on the 18th and later. Milkweeds were scarce -being found in gardens, burned over areas and the edges of roads. Milkweed sprouts in fields were not up or were hidden beneath grasses and weeds. Unfortunately, the temperatures have been colder than normal and none of the hundreds of milkweed stems I’ve surveyed have shown signs of larval feeding even though most of these plants had eggs at one time. At this writing – 26 April – it appears that most of this early reproduction won’t be successful. If so, moving into the mid latitudes earlier than normal will not contribute substantially to population growth this year. In short, it would have been better had these monarchs laid these eggs further south where temperatures were more favorable for growth and development.

In addition to watching the pattern of the returning butterflies, I monitor other conditions – temperature, rainfall, drought, abundance of fire ants, etc., as they play out each month of the breeding season. As you’ve heard from me before, Texas is key. For the monarchs to have a good year, the conditions in Texas for the first generation have to be favorable. If they are, the population grows, as it did last year. If unfavorable, as they have been in a number of years such as 2004, the population declines. Conditions in Texas this spring have been hot and dry – a significant drought. Milkweeds have been abundant and nectar seems to have been available in most locations but due to high winds and temperatures monarchs just kept moving. The result is that monarchs are not off to a good start and the prospects that the population will rebound in the summer months are getting slimmer each day.

At the end of March, I was saying that the population this coming winter would be no greater than 5 hectares due to conditions in Texas. In contrast, at the end of March in 2010 it was quite clear that the population was going to increase and the only question was by how much; it more than doubled from 1.92 to 4.02. It now appears that the 5-hectare prediction was too optimistic. Four hectares (4.02 last year) is possible but not too likely. If the long-range forecasts for the northern breeding areas are accurate, and they have been recently, the prospect for producing a large monarch population in and north of the corn belt is not great. In fact, the population could drop back to 2009 numbers (1.92 hectares), if the summer is as cold as forecast.

In a week or more – weather permitting – first generation monarchs from Texas should begin migrating through this area to colonize the northern breeding areas. The numbers reaching these northern habitats is largely a function of reproduction in Texas and the weather conditions in May. Reproduction is Texas has yet to play out in numbers, but if past seasons are a good measure, the number moving northward should be less than expected based on the size of the overwintering population. Below normal temperatures are projected for May, which, if true, would limit the number of monarchs reaching the milkweed patches throughout the northern breeding area and ultimately the size of the fall migratory population. While we can hope that the long-range forecasts are wrong, and that reproduction will be higher than I’m envisioning, the prospects – at this date – favor a migration that will result in an overwintering population of 2-4 hectares.

We can’t do anything about the physical conditions that drive the monarch population but we can provide the milkweed and nectar resources they need – PLANT MILKWEED!

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Monarch Watch Tag Recovery Database Updated

22 April 2011 | Author: Jim Lovett

Nearly 4, 000 records have been added to the Monarch Watch Tag Recovery database, bringing the total number of records to more than 15, 000 for the 1992-2010 monarch tagging seasons.

Approximately 2500 records represent monarchs observed/recovered in the U.S. or Canada and more than 12, 500 records represent monarchs recovered at the overwintering sites in Mexico.

Anyone may search the database via monarchwatch.org/recoveries

Please note that this is very much a work in progress – we working on acquiring the funding necessary to “scrub” the data (clean up any errors) and create more robust applications for searching and data visualization. Also, you will likely notice records with missing data – this is often due to taggers not returning their datasheets at the end of the tagging season. We are in the process of tracking down the missing data and will update the database as we recover the information.

If you would like to help fund this project, please see our Donation page for details about ways to give.

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