Migrants Return

Monarch (Danaus plexippus)

A lot of my birder friends are getting all swoon-y over the spring bird migration. I need to step up and celebrate the return of the migrating insects. Last weekend at the Fen, Leon and Kevin saw a very worn Monarch. Unfortunately, I was not with them when it happened, but it's always a delight to hear. A quick perusal of the Journey North website's interactive map reveals that the observation is right in line with what's been reported elsewhere in the country. The monarchs that are getting here right now were born in Texas about a month ago. They are the offspring of the butterflies that spent the winter in the Transvolcanic Mountains of Mexico.

Green Darner (Anax junius) Photo: Wikipedia Commons

It isn't just the monarchs- other insect migrants are arriving as well. It's much less widely known that some dragonflies also migrate. The green darner is the best-studied example. The details are much less well worked out than they are for monarchs. Confounding matters even further, some green darners head south for the winter. Others spend the winter up here in the north. Dragonflies begin their lives as aquatic creatures called nymphs or naiads. In late summer about half of the naiads complete their development. They migrate to the Gulf Coast and Peninsular Florida. The other half of the naiads spend the winter in the northern lakes and ponds. They complete their development the following spring- and emerge at about the same time that the migrants return. Over the past week and a half I've been seeing lots of green darners. Are they returning migrants, or newly emerged from naiads that overwintered? It's hard to say- but it's great to have them back.