Saturday, December 4, 2021

Mesonet at SD State Eagle Butte realtime weather web widget

Birds and wind

I took a walk just as the winds from last week’s storm really started kicking up. I saw almost none of the birds I expected to see, just a pair of Bald Eagles circling high above the park. Could the birds tell a storm was coming? And what do they do in the gale-force winds of a hurricane or windstorm?  

Research suggests that birds are sensitive to changes in barometric pressure and can tell when a storm is on the way. Increased feeding activity might be one sign, or feeding in inclement weather, when they would normally try to wait it out. Migratory birds might leave earlier than they otherwise would, while others might change or even reverse their course to avoid a storm. 

The days after big storms are often great for birding. After Hurricane Sandy hit New York in 2012, there were sightings of pelagic birds—that is, birds that spend most or all of their lives over the open ocean—in Manhattan and even further inland. I saw my first Northern Gannet after Sandy. Gannets are uncommon visitors to the waters off Brooklyn. Large white birds, they are distinguished from gulls by their yellow heads and sharp bluish beaks—and by their spectacular dives straight down from great heights to catch their prey. 

GPS tagging allows ornithologists to follow birds through storms. A Whimbrel named Hope was tracked flying through Tropical Storm Gert in 2011. As described in Forbes, “she endured strong headwinds for 27 hours straight, and was able to fly at . . . only 7 miles per hour. . . . [A]fter she successfully emerged from the middle of that storm, she then was pushed by strong tailwinds at . . . 90 miles per hour.” I’ve seen this described as a “slingshot” effect, and birds that can survive the hours in the air can use the winds to get where they’re going faster. 

Most of the birds in our back yards are passerines, or in the order Passeriformes. Passerines are perching birds and make up over half of the known birds globally, so it’s easier to say which of our backyard birds are not passerines: hummingbirds, woodpeckers, and swifts are the most common. It’s these birds that I worried about most in big storms. Unlike the gannets, which can weigh five or six pounds, most passerines weigh only a few ounces. I imagined them being blown about like dry leaves.

It turns out, though, that I needn’t have worried. Perching birds’ feet clinch when they relax so that their toes—three in front and one in back—hold tight to the branch or wire they’ve settled on. This allows them to sleep while perching, and it allows them to maintain that grip in very high winds. As long as the branch they are perched on doesn’t break, they are unlikely to come to harm. 

This is all good news, especially as storms seem to be becoming more frequent. But what happens when you add subfreezing temperatures and a foot of snow to the mix? That’s a question for next time. 

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