Monarch Watch Blog

Monarch Population Status

Saturday, September 5th, 2009 at 3:44 pm by Chip Taylor
Filed under Monarch Population Status | 9 Comments »

As many of you know, the fall monarch migration is well underway. In July when I wrote the text for the Premigration Newsletter (available for download at it was already clear that the fall migration would be modest and certainly no larger than the migrations we have seen for the last several years. It is now clear that the migration this year will be smaller than any seen since the fall of 2004, a migration that resulted in an all-time low overwintering population in Mexico of 2.19 hectares.

The overwintering population this winter will probably be less than 4 hectares and could be much less if the long term drought that has persisted in much of Texas and northeastern Mexico doesn’t abate. Monarchs are highly dependent on nectar and sources of water to fuel the migration through this region in October and November and, if the drought persists and nectar resources are scarce during this period, the number of monarchs reaching the overwintering sites will be reduced. There have been some recent rains in Texas but it is not yet clear whether these rains have been sufficient or widespread enough to provide the fall flowers needed by the monarchs.

  1. 9 Responses to “Monarch Population Status”

  2. By Paul Cherubini on Sep 10, 2009

    I disagree that “that the migration this year will be smaller than any seen since the fall of 2004”. I think the migration will be strong in Kansas Sept. 10-25 and that it will be possible to take videos of evening roosts containing 500-1000 monarchs at locations within 60 miles of Lawrence, Kansas. I also expect the overwintering population in Mexico will total 6-9 hectares in size regardless of drought conditions in Texas. In my experience, sunflowers are abundant in Texas every Sept-October regardless of the weather,

  3. By janbrit on Sep 20, 2009

    I live in CT and I am very fond of Monarchs, having raised them over the years from egg to butterfly. This year I have not seen a single monarch either here or in NH where I have spent time this summer. Its disappointing. I might go down to the coast this coming week and wonder if I’ll see the butterflies gathering and getting ready to migrate ( as in other years ) I have been wondering where they have gone ?

  4. By Bill Evans on Sep 21, 2009

    The Monarch migration through central New York State this fall is the lowest I’ve ever seen (~20 years). A 200 mile drive yesterday through open country revealed only 2. 100 mile drives each of the past two weeks produced none. Peak migration through the Ithaca, NY area typically occurs during the middle two weeks of September.

    They came through here in good numbers in May. We had a cool rainy spring and early summer, but I wonder if something else has compounded their population crash. It is astonishing not to see them flying here at this time of year.

  5. By janbrit on Sep 25, 2009

    I was at the beach yesterday,in Waterford next to New London ( CT ) It was perhaps the last very warm day of the season. I was interested to note the butterflies – in previous years at this time I have seen MANY fluttering around getting ready to migrate. Yesterday I saw a very few ( the first time I have seen a Monarch at all this year! )

  6. By Barb Agnew on Oct 3, 2009

    This has been the saddest year for many butterflies and the Monarch was no exception. The Migration was even more depressing as there were no clusters or roosts on The Monarch Trail here in Wauwatosa Wi. 12 years of watching and always there were beautiful days in the Boneset, and large or small, there were clusters in the Sycamore and Oaks. Even in 2004 a group came to roost on the 26th and 27th of september. Sparse and far between this year, I will continue our preservation effort on this habitat!

  7. By Barbara Blake on Oct 13, 2009

    Ilive near Houston, Tx and have maintained a Monarch garden for years. This last month more than 50 have hatched and gotten on their way to Mexico. I hope they make it.

  8. By Joseph Ross on Oct 14, 2009

    Our efforts here in Wisconsin this summer have had much success turning gardens and parks into Waystations. The populations may be down but the education is up! We are working to improve the migration routes and further preserve the overwintering sites thanks to continuing efforts by Chip Taylor, Prof. Lincoln Brower, the Michoacan Reforestation Fund, Jose Alvarez of the La Cruz Habitat Protection Project Mexico and good folks like you.

  9. By Joseph Ross on Oct 14, 2009

    Anyone traveling to the Preserve for the Day of the Dead Celebration this year? Its a full moon that night, spooky. See ya there.

  10. By tracy on Oct 20, 2009

    It looks like we have one waylaid and withering monarch here in Shutesbury, MA this evening. We’ve just had a weekend with snow and hard frost and then today, it was almost 70 — I assume this one is dying? I have never seen one close up before, and I know very little about these butterflies.

    If in fact this is a dying monarch, is there anything I can do, short of packing it with me on the trip to Dallas in 2 days?…(if only)

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