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.
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
We 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?
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.”
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.
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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