Fall Migration: Midnight Flights
By: Karen Menard
“Did you ever get a chance to hear the midnight flight of birds passing through the air and darkness overhead, in countless armies, changing their early or late summer habitat? It is something not to be forgotten. You could hear the characteristic motion--- once or twice the rush of mighty wings, but often a velvety rustle, long drawn out---sometimes quite near---with continual calls and chirps, and some song notes. It all lasted from 12 till 3.” Walt Whitman
Each fall, billions of birds go the distance and migrate south in exchange for important biological advantages. The tropics offer warmer weather and a bounty of food resources that can assist in keeping a bird fit and ready for the next breeding season. However, the more time birds spend in migratory transit, the more they are put at risk for casualties due to issues such as harsh weather conditions, habitat loss, predation, and object strikes. Sadly, it is estimated that approximately 50% of the birds that set out on their annual migratory journeys will not return to their northern breeding grounds in the spring due to mortality.
A vast majority of songbird migration goes on over our heads in the darkness as we are sleeping, and it is a fascinating phenomenon that scientists have been studying for quite a long time. In fact, early on, Aristotle was credited with the idea that birds actually hibernate. That theory was thought to be true for about 2,000 years! The belief was that swallows spent their winters in the mud of marshes. There was an even more remarkable theory that suggested birds flew to the moon for the winter.
What we do know today is that birds spend a good amount of time fueling up and storing sufficient fat reserves before heading out of town. As they pack on extra grams, their internal organs often shrink and undergo dramatic transformations in order to most efficiently get to their final destinations. Ultimately, their powerful journey south is accomplished primarily by muscled propulsion, but they will get a boost from the wind whenever they can.
All in all, bird navigation is complex. Currently, there are still directional skill mysteries that humans have yet to unravel, but scientists have uncovered that birds do combine many types of senses as they navigate. They can perceive compass information from the stars, the sun, and also by sensing the earth’s magnetic field. Information from landmarks, as well as the position of the setting sun is also used in wayfinding.
It’s difficult to imagine that just about ten days ago, an estimated 1,751,900 birds passed over Lucas County, with numbers in the thousands each day since (see link for numbers: https://dashboard.birdcast.info/). This immense amount of animals that fly over our own backyards on their arduous journey is a testament to the importance of northwest Ohio bird conservation. Valuable stopover habitat along Lake Erie and in the Metroparks contributes to migratory bird success and is key to sustaining global bird populations.
Did you know? There is much research happening in regard to bird migration. Go to: https://explorer.audubon.org/ and check out how different species are tracked, as well as recent scientific findings.