Laboratory for Biology of Terrestrial Arthropods: Butterfly Bonanza at Lighthouse Point!

Want some cool lepidoptera? Here's a hot collection tip:

Last week, right before the beautiful weather turned God-awful, I went to Lighthouse Point Park in East Haven. It's on the Eastern edge of New Haven Harbor, easily accessible off Townsend Ave (take a right on lighthouse road, ignore the check-in booths in the off-season). It's famous for hawk migration, and right now is in fact peak season if you want to go see some eagles, falcons, and vultures (albeit at some distance). But the butterfly spectacle that unfolded while I was there beat any insect-related event I'd seen before.

1,100 Monarchs.
200 Painted Ladies.
2 Black Swallowtails.
100-350 Skipper spp (small, so difficult to group-count or estimate group densities)
8 Common Buckeyes.
A handful of Red Admirals.

Birders tally sometimes tally migrating hawks by counting individuals in a cluster or fraction of a group, and multiplying out to get a sense of the full scale. This is probably a useful simple strategy for insects as well. For example, the monarch count breaks down to about six bushes with roughly 75 monarchs, eight with about 40 on them, and about 330 in groups milling about or migrating down the coast.

All of these Monarchs were on their way to Oyamel Fir forests in and around Michoacan and DF, Mexico, where they will gather in even more incredible densities- often tens of thousands to a tree. They live for a few weeks each and migrate north over several generations in the spring, but then produce a "methuselah generation" that marathons all the way back to Mexico. In the mean time, they rely on stopover points along the coast to refuel. Lighthouse Point Park has a nectar garden that serves as a critical migration site for many butterflies in a sea of suburban coastal development and saltmarshes (which have no nectar plants). Fall-flowering plants are especially important to monarchs, and the garden has a packed an impressive diversity of fall-flowering nectar plants into not very much space. The garden has a big plaque explaining butterfly migration, and our own Val Morley is listed as one of the authors at the bottom. It's worth a visit, and Monarch migration is definitely worth reading up on.

^This
Happens here v (Angangueo, Michoacan. Habitat loss and human encroachment is a whole other story, but a very big problem, as you might be able to infer from this image)

The migration of Painted Ladies (though they are the most widely distributed butterfly in the world) is slightly less well-understood. They don't winter north of the frost line, but they are irruptive migrants- they don't seem to have seasonal patterns so much as they seem to go through population cycles and show up where the food is. Buckeyes, too, have complex migration patterns, and we are right at the tip of their range of regular occurance. I'm always excited to see them, since I've lived all my life in Boston and can remember seeing only one. But in CT over the past year, I've seen them over a dozen times just as a casual observer.

In fact, the only reason we know much of anything about Monarch migration is because of tagging programs. We can track these suckers with some accuracy thanks to a great transcontinental network of citizen scientists. One of the butterflies at Lighthouse Point was tagged, and I of course called in the band number to the hotline printed in tiny font on its wing.