Tuesday, November 10, 2009

Laura Erickson: Migration

“At whatever moment you read these words, day or night, there are birds aloft in the skies of the Western Hemisphere, migrating.” These are the words that open Scott Weidensaul’s exquisite book, Living on the Wind: Across the Hemisphere with Migratory Birds. By November 1 most of the birds headed to the tropics are “south of the border” already, but a great many birds — Canada geese, blue jays, robins, pine and yellow-rumped warblers, white-throated sparrows, and more — are still on the move.

Robins pigging out on berries are still abundant in northern states. On Halloween 14,817 robins were counted at Hawk Ridge Bird Observatory in Duluth, Minnesota. They were all working their way south, but throughout the day people were also seeing robins feeding on crab apples, mountain ash berries, and other fruits. Robins have two different lifestyles, depending on the season. When snows melt in spring, they become specialists on earthworms and insects and grow very territorial. As the young grow independent and adults stop raising young, they turn into sociable fruit eaters, roosting at night in large flocks, and feeding together in fruit trees.

Most blue jays remain in far northern areas throughout the winter, but many of them also migrate. No one has been able to figure out exactly how to predict whether an individual blue jay will remain for the winter or leave, but we do know that during winter, flocks of jays are most numerous where acorn supplies are richest.

More and more Canada geese are remaining in the north wherever they can find some open water and where snows melt at least enough to allow them to feed on waste grain. These extremely sociable birds often join with brothers and sisters and parents even when they themselves are great-grandparents!

People with feeding stations may be noticing a variety of sparrows feeding on the ground beneath their feeders. Some may be tricky for beginners to identify, but feeder birds at least offer us more time to observe and tease out identifications than most birds in the wild do. During November we often don’t realize that the birds we’re seeing at our feeders change from day to day. We may have 20 goldfinches one day and 20 the next without ever noticing that they’re completely different individuals.

Birds are mostly quiet in November, so they’re not as obvious and noticeable as in other seasons, but searching them out is fun and rewarding.

Laura Erickson is science editor at the Cornell Lab of Ornithology. She is the author of The Bird Watching Answer Book and the winner of the National Outdoor Book Award. She also writes “Twin Beaks, the first blog by birds and for birds.” Laura migrates between her house and husband in Duluth, Minnesota, and her apartment and job in Ithaca, New York, where she lives with her dog, Photon; her indoor cat Kasey; and an education eastern screech owl named Archimedes.

All photos by Laura Erickson.

No comments: