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Oct 22, 2019 10:27 AMPublication: The East Hampton Press & The Southampton Press

Fall Butterfly Sightings

Oct 22, 2019 5:52 PM

The monarch butterfly has gotten so much “ink” over the past decade, that it seems most people now recognize the stunning winged adults, and many are somewhat familiar with its amazing life history story.


But as is the case with most wildlife species, even those that have been studied carefully for many years, there are a few mysteries that crop up as scientists delve deeper and deeper into the research. I wrote about an example of this earlier this month in my October 9 column: Mark Elbroch’s research findings on mountain lions that contradicted several long standing beliefs on that species’ life history.

A study published earlier this year found that not all the monarchs in eastern North America migrate to overwintering sites in Mexico. Some migrate to south Florida, an area thought to be exclusively occupied by a population of non-migratory monarchs. Using a technique called “stable isotope analysis” and sampling the wings of a subset of this population during the winter, researchers discovered that 48 percent of the south Florida population originated from Texas, the Midwest and other parts of the monarch’s summer breeding range.

And unlike the behavior of the overwintering population in Mexico, the south Florida migrants are active all winter, mixing with the locals and feeding on the nectar found among the abundant flowering plants there. It is not known how many of the Florida migrants move north in the spring to breed. “I think it’s very important to keep benchmarking it and tracking it,” said University of Florida biologist Marta Wayne, the author of the new study.

This past weekend, I joined Jamaica Bay Guardian Don Riepe for a walk on his home turf at the Jamaica Bay Wildlife Refuge. Among his many naturalist skills, Don is an expert at identifying butterflies, and it was a perfect sunny day to glimpse a number of interesting species at the refuge.

Several of these, while not making as spectacular a migration as the monarch, do include migration in their life histories. We found an eastern comma perched on a black cherry on the edge of the nature trail. At rest, when its wings are folded and its bright reddish-orange topsides are hidden from sight, its brown-colored underwings resemble a dead leaf. However, this individual rested on a live cherry leaf, and was quite conspicuous.

Some adults will overwinter here, relying on rotting fruit as sustenance in late fall, tree sap in late winter, and a good supply of glycerol, or antifreeze, to survive cold mid-winter snaps. Others will fly south for warmer climes.

The red admiral cannot survive the cold, and much of its North American range (it is found along the eastern seaboard as far north as Newfoundland) must be recolonized every spring by migrants from the south.

We spotted several common buckeyes in their typical behavior and favored habitat: resting on the sandy soil in full sun with wings spread wide soaking up the rays. This striking butterfly is described as an “immigrant” due to the fact that its migration pattern is a one-way trip. As with the red admiral, adults here will not survive the winter, but apparently they may not attempt to fly south. Instead, our local population comprises individuals reared down south in the spring and looking to escape the crowds and find better pastures up north.

Another immigrant is the painted lady. From the offspring of permanent, year-round populations in Mexico and overwintering adults down south, newly metamorphosed adults move north every spring to repopulate much of their summer breeding range in North America. Its population is known to vary greatly from year to year.

The American lady does migrate, heading south to warmer climes at this time of year. But based on the lifespan listed in the literature for the adult form, it appears that the adults will not live through the winter. Rather, their migration south is to mate and lay eggs in an environment in which the eggs and larval stages can survive the coming winter.

 

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