Llano River Ready for “Premigration Migration” of Monarch Butterflies

Email lists have been filled with optimistic reports on the Monarch migration in recent weeks. We’re feeling hopeful of a rebound.

Folks from Canada to Pennsylvania sang a buoyant chorus:  more butterflies than last year.  Of course, it’s all relative:  with 2013 holding the distinction as the worst migration in history, even a slight uptick in Monarch butterfly numbers would call for celebration.

Monarch on swamp milkweed

Pretty, early girl. Faded female Monarch on Swamp Milkweed in downtown San Antonio, August 14, 2014. Photo by Monika Maeckle

Here’s a sampling of updates:

It has been the best year finding them, in 11 years of doing this. Most were from our yard.

–J Agazzi, SE Wisconsin on the Illinois border

I also live in SE WI and have about 30 just-born instars taken from swamp milkweed more than common milkweed. I agree also that this has been a good year and I’m still finding them.

–Chris Mason,  Lake Geneva, WI

A BIG comeback for Monarchs this year…. Having gathered and raised hundreds of Monarchs for past ten years; having been very sad over numbers next to nothing in 2012 & 2013, this year ‘s population is back up to 75 releases and more to come. I am amazed, overjoyed.   (Interestingly, I and others observed only a single Monarch here and there during this entire season. But how joyfully ‘active’ these ‘singles’ have been!)
                                –Cindy Ziebell, Eua Claire, Wisconsin

I have to agree with you all….although it is not scientific, I have recorded seeing at least one monarch every day for the last 4.5 weeks!! Sometimes I have seen as many as five in a day. This has not happened in at least 20 years! I really hope that our fall migration numbers follow these trends. It is also the only year I can remember collecting more than one or two eggs. This week, I have collected eight. Good to hear all this news from this central region.

–Jim and Linette Langhus, Monona Iowa

IMG_1637We learn in Monarch Migration 101 that the migratory generation of Monarchs do not reproduce.  Rather, they go into a reproductive diapause, a biological state of arrested development that interrupts their usual instinct to procreate.  Presumably, they do this to save their energy for the long flight and months-long overwintering in Mexico, conserving biological resources to awake in the spring and reproduce then.

Yet in late summer, we generally see a pulse of Monarchs over Labor Day weekend and many leave eggs as evidence of the reproductivity and their travels.

So what’s going on with these “joyfully active” single butterflies described above?

Goldenrod Llano River

Goldenrod, a favorite nectar source for Monarch butterflies during the fall migration, awaits on the Llano River in the Texas Hill Country. Photo by Monika Maeckle

For years, scientists like  Dr. Chip Taylor of Monarch Watch and Dr. Karen Oberhauser of Monarch Larvae Monitoring Project (MLMP) have described a “premigration migration” that begins in mid-July and carries a final reproductive generation of Monarchs south.

Candy Sarikonda explains the phenomenon in this issue of the MLMP newsletter. 

Taylor has speculated that late season reproduction is selectively advantageous for some Monarchs who are born too far north too late in the year to complete the lifecycle.   Dr. Karen Oberhauser, founder of the MLMP, and an evolutionary scientist at the University of Minnesota, told Sarikonda that “It makes evolutionary sense that some monarchs would fly south as they laid their eggs, since an egg laid in August in Missouri or Virginia is probably more likely to develop and migrate to Mexico than one laid in Minnesota, where a hard freeze in early September is not that uncommon.”

What'syour latitude.  Monarch Watch predicts peak Monarch activity by latitude each fall.

What’s your latitude? Monarch Watch predicts peak Monarch activity by latitude each fall.

We don’t fully understand the reasons for this premigration migration, but we do know that here in Texas, the Llano River is well-stocked with milkweed for those premigratory migrants.   Last Sunday we saw ample Swamp Milkweed and Goldenrod lining the banks, and heavy rains this weekend will keep the host and nectar plants fresh for Monarchs arriving later this summer.

For our area, latitude 28, the peak migration will occur somewhere between October 10 and 27.  Check the chart above to see when peak migration is expected in your neighborhood–or goto the Monarch Watch website.

How convenient: eggs laid over Labor Day weekend will be hatching just as the peak migration passes through the Texas Hill Country in mid October.  That means our freshly hatched, well-fed Monarchs will have an excellent chance of making it to Michoacán.

From the Texas Hill Country to Michoacan!  MJR894 was recovered on the florest floor and reported last week.  The butterfly was tagged on October 11, 2011 with Dr. Lincoln Brower.  Photo by Monika Maeckle

From the Texas Hill Country to Michoacan! two Monarch butterflies tagged at the ranch 10/12/13 were recovered on the florest floor and recovered 2/22/14. Photo by Monika Maeckle

Perhaps that was the case with two Monarch butterflies tagged at the ranch last year on October 12.  Monarch Watch just posted a preliminary report on the 2013 season’s recoveries. 

SLM131, a male, was tagged along the Llano River by friends Omar Rodriguez and Veronica Prida and was found at EL Rosario in February.   A female I tagged the same day, SLM181, was also found at the sanctuary on 2/22/14.

All the elements are in place for a recovery of the Monarch population this year.  Stay tuned for updates.

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7 thoughts on “Llano River Ready for “Premigration Migration” of Monarch Butterflies

  1. I brought 33 chrys from Maine to Denver. Released two males, caged two females and watching three new hatches this a.m. Still hanging/drying. The “girls” flew away (I have plenty of flowers and milkweed) Should I cage the new three or just release all five and hope they stick around ? And mate ? Still time before migration ?

  2. Stubborn northerly winds in Minnesota are delaying the formation of roosts that typically appear during the 3rd week in August: http://hint.fm/wind/ But because the migratory population is much higher this year, there will be many fall roost reports on Journey North in Minnesota and Iowa & Nebraska once the wind shifts around South and keeps blowing from the south for a few days or more.

  3. Here in north illinois we have been seeing some every few days and its not quite “peak” according to that chart above. Saw another last night and am very hopeful for this year. We planted a nectar bar out back with about 20-30 feet of highly productive flowering plants and they are coming into their own now. Seen lots of other butterflies as well, mainly swallowtails of all kinds. Next year will be better. We also have some milkweed out back 🙂

  4. I just released my first monarch butterfly. A female. My interest sparked after attending a Butterfly Festival at Beaver Creek Reserve in Fall Creek, WI. I only have one other chrysalis waiting.

  5. I live on Shaw Island Road (CR 225) in Bluffton, Llano County, Texas, right on Lake Buchanan. Last year (2013) I had an incredible number of Monarchs on my property. They liked to congregate in a native cane brake I cultivated on my property. I kept wondering if they would return again this year…and hoping…. Yesterday evening as the last of the sun was setting and the moon was rising, I saw that the Monarchs had indeed returned. So miraculous and uplifting.

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