Nature Note #202: Fall Flight

As fall draws closer, migration is in full swing with birds, dragonflies, and butterflies traveling hundreds of miles to reach wintering grounds along the coast, towards the interior, or even further south towards Mexico and South America. At the Trinity Center, some of our most noticeable migrants are yellow-bellied sapsuckers, cloudless sulphur butterflies and, green darner dragonflies. Animal migration is triggered by several factors including seasonal changes, food availability, and reproductive needs. During this time of year, I keep my eyes peeled to look out for these incredible travelers, allowing me to catch a glimpse of an important event in Nature’s calendar.

Sapsucker and bluebird at Stony Brook-Millstone Preserve in Pennington, NJ. Photo by me. 

Yellow-bellied sapsuckers (Sphyrapicus varius) are common winter residents to the pine forests of coastal North Carolina. While their name is certainly creative, they don’t exactly suck sap. As a member of the woodpecker family, they use their sturdy, pointed bills to peck away at the tree bark to reach grubs and beetles that burrow through the wood and inner bark. They also use their bills to create small rows of holes around the trunks and branches to allow sap to flow out. Afterwards, they use their long tongues to sweep the sap out of those holes. Their preferred trees include hickories, maples, and birches. In the summer, they breed throughout most of the Canadian provinces, New England, and the upper Midwest, before migrating to the southeast in the mid-fall.

Cloudless sulphur enjoying a quick treat near the registration office. Photo by me.

Insects migrate as well with some like the cloudless sulphur butterfly (Phoebis sennae) completing short journeys, while others like green darner dragonflies (Anax junius) complete treks that can cover over a thousand miles in just a few weeks. The cloudless sulphur is well named with lemon yellow wings with minute white spots on the wings of females. I have found them most often when I’m walking on my way to class and delight in seeing them determinedly fluttering to wherever they deem they need to be at that moment. While most animals migrate with a destination in mind, sulphurs only care about reaching a warmer climate. Once that is satisfied, eggs will be laid, the adults die off and their life cycle starts anew.

Female green darner on wooden fence.
Retrieved from Wikipedia, photo by Bruce Martin

On the other hand, the green darner dragonfly can undertake an incredibly long journey. While flying along the coast, they can travel up to 60 miles in a day. If a lone dragonfly were to fly from Moosehead Lake in Maine all the way to Trinity Center, it would only take it two weeks to travel the distance! When migrating, time is not their ally. By this time in their lives, many will have already spent up to two years living in their larval form at the bottom of muddy ponds and wetlands before metamorphosing into their familiar adult forms. Upon getting their adult bodies, they only have four to seven weeks to live before dying, so for them, the need to migrate and breed is especially urgent.

I hope that this fall you will have the opportunity to look out for these creatures as they visit and pass through. Knowing a little more about their stories makes their exoduses seem all the more impressive, inspiring, and incredible and gives us a window into a world we don’t often get to appreciate. 

"Migrations like this leave us staggered; we are such stodgy, rooted creatures. To think of crossing thousands of miles under our own power is as incomprehensible as jumping to the moon. Yet even the tiniest of birds perform such miracles." - Scott Weidensaul