Passing Passerines -Fall 2016

by: Virginia Andrews

Fall is a time of transition for birds as well as people, and these are golden months on Nantucket, when we never know what will show up.

In the fall there are many young birds, the so-called “birds of the year.” Some birders like to refer to them as “the Class of 2016.” Populations are at peak numbers, both for year-round residents and migratory species. Hatched here or in northern forests or tundra, migratory birds must all attempt to find their way south to get food in the winter. Many follow the coasts, where the ocean, slower to warm in spring, but also slower to cool than the land in the fall, moderates the temperatures. This allows insect life – bird food to them – to continue later in the season. For them, Nantucket is an oasis of life in an otherwise inhospitable ocean.

Migratory birds leave the nest, and their home patch, to fly thousands of miles to a place they have never seen before. And if they are smart, strong and lucky, the next year they return to the area where they hatched. Scientists still do not know exactly how they navigate. Banding and geolocator studies clearly indicate that they find their way back and forth with incredible accuracy. Birds have done so for millions of years, all without the benefit of maps, compasses or chronometers. They somehow evolved a biological GPS. It is difficult to tease out facts from highly-mobile wild creatures, but scientists are getting intriguing results.

Different species of birds have different ways of navigating. Ornithologists used a planetarium to discover that Indigo Buntings, for example, use the stars to find their way. Like many species they are night migrants. Cooler temperatures help keep them from overheating, and they have fewer bird-snacking hawks to escape. Other species appear to have a cellular magnetic compass, while still others are sensitive to polarized light. But exactly how these innate abilities work is still a mystery.

In some cases, for reasons unknown, the map sense or directional skill goes awry. About 10 percent of birds, it is thought, head off in the wrong direction. If

one finds suitable habitat, and a mate, a new territory may be discovered, a new population founded. Instead of exhibiting life-threatening foolishness, they become pioneers. If their original climate changes, they might then be the saviors of their species. Of course, sometimes skill has nothing to do with it. Birds use the winds as well as their wings. So wind and weather can send them in unexpected directions.

In the fall of 2012 as a hurricane named Sandy wandered up the coast of North America, it was joined by a storm from Europe. The wind had blown steadily east for 10 days. Caught up in it was a flock of European shorebirds called Northern Lapwings. Separated from each other by the storm, the hapless birds were seen by birders from Nova Scotia to Virginia. Two made it to the hospitable fields of Bartlett’s Ocean View Farm on Nantucket, where they spent the winter. In the spring they were joined by a third, and in April all three took off again, presumably heading back home for another breeding season.

In the meantime, North American birders flocked to see this European species, suddenly available much closer to home. Other European species that have landed on Nantucket include a Ruff, the Scaup-like Tufted Duck, a Black-headed Gull which appears to have become a regular winter visitor, and Lesser Black-backed Gulls, which can be seen almost any day between November and April on Sconset beaches. But regional birders are excited by the surprise appearances of southern and western species, too. Three Brown Pelicans, birds of the year banded in Virginia, also dropped in courtesy of Hurricane Sandy, and are sometimes seen off our shores. Western Kingbirds are now fall regulars. There is the occasional Scissortailed Flycatcher, Northern Wheatear or Townsend’s Solitaire. One eastern record discovered by birding-festival leader Simon Perkins in 2012, was a very rare Graytailed Tattler. This Asian species is sometimes found on islands in western Alaska, and once, here on Nantucket. Almost equally out of place was a Calliope Hummingbird, North America’s smallest, more at home in the Rocky Mountains then a sandy island off the East Coast.

Birding can become a particular kind of strange obsession, as chronicled in the

book “The Big Year” and movie of the same name. For some it’s the list that matters. For others, the behavior of a bird, no matter how apparently common, is enough to spark their curiosity. Nonetheless, every birder enjoys the sight of a free, wild, feathered creature, and the challenge of identification.

There is no denying that identifying birds in the fall is a worthy challenge. They don’t call them “confusing fall warblers” for nothing. But this is part of what makes birding both frustrating and satisfying. It takes skill and luck to learn and observe details well. Is it a Pine Warbler, a Bay-breasted, or a Blackpoll? They differ in the shape of bill, streaking or lack thereof, or in the case of the Blackpoll Warbler, yellow feet. Blackpolls are astounding athletes, even in the bird world. They take off from Nantucket, but are known to make the entire trip to South America in one big jump, an uninterrupted flight of thousands of miles.

And if warblers weren’t enough, Nantucket also gets its fair share of shorebirds, including the highly-endangered Piping Plover, which nests here, and the Red Knot, which does not. We have seen Marbled and Hudsonian Godwits, Buffbreasted Sandpipers, Pecks and Purples, Stilts and Solitaries. American Oystercatchers, with their big bright-red bills, stand out on shoals and mud flats, grazing on clams or marine worms. They too are under threat, and a desirable species on many lists.

Birders love the fall here, but even the most casual observer cannot help but be struck by the sheer beauty of Nantucket’s bird life, the rare jewels in an equally rare setting. ///

Virginia Andrews writes the weekly “Island Bird Sightings” column for The Inquirer and Mirror and is a regular feature writer for Nantucket Today.

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