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Are Your Birds Southbound, Just Arriving, Or Homebodies?

Many of us backyard birdwatchers are witnessing the change of the seasons this month, with hummingbirds no longer visiting our flowers or nectar feeders and large groupings of other birds moving out.

But is it just goodbye to migrants and a familiar nod to year-round residents?

Is that chickadee you've been watching flit in and out of a nestbox all summer the same one you'll see at your winter feeder a few months down the road? When you look at that "year-round range" map stretching from Alaska to the southwest U.S. in your field guide, do you wonder if your summertime chickadee is beating wings to New Mexico for the winter, and the ones you see this fall just moved in from British Columbia?

Are your backyard birds heading south, just arriving from parts north, or are they homebodies hanging out 24-7-365?

Chances are, it's a little bit of all three, depending on the species using your backyard wildlife habitat.

As experts at the Cornell Lab of Ornithology say, migratory patterns vary by species and sometimes within the same species.

Short distance migrants often include species that are permanent residents in most of their range, but with migratory tendencies on the edges or in pockets of their range.

Hairy woodpeckers are primarily non-migratory, permanent residents throughout their breeding range. However, northernmost populations display irregular and unpredictable wandering in winter. Local post-nesting short-distance movements take place in some areas. In some situations individuals breeding at higher altitudes seem to disperse to lower altitudes during non-breeding season or from inland to coastal locations.

This may be the migrating pattern category that fits one of our most common backyard winter feeding station visitors - the black-capped chickadee.

Medium distance migrants tend to exhibit a variety of irregular patterns of north/south migration but remain in North America.

Jays in general tend to fit this pattern, although much remains a mystery. Here in the Pacific Northwest, some Steller's jays are present throughout the winter in all parts of the range. Young jays may be more likely to migrate than adults. Some individual jays may migrate south in one year, stay north the next winter, and then migrate south again the next year. Many who feed birds in their backyard may be seeing one population of jays in the winter and an entirely different population of jays in the summer.

The northernmost breeding population of white-crowned sparrows migrates from Alaska and the Yukon to the southern plains of the United States and into northern Mexico. A different subspecies breeds farther south, ranging from British Columbia to northern California. These white-crowns migrate a shorter distance to the lowlands of central and southern California. A third subspecies is a permanent resident in parts of coastal California.

Killdeer are classified as medium-distance partial migrants, another way of saying their movements are complex and poorly understood. Banding records suggest general southward fall migration in North American birds, with no strong directional orientation. Some killdeer migrate through western North America and Central America while others winter in the coastal and wetland areas of California.

Some wrens, red-winged blackbirds, house finches, goldfinches, juncos and evening grosbeaks may fit this category, too, breeding in Canada or here in Washington, and some wintering here or in Oregon, California, and other southwest states or Mexico.

And then there are the really mysterious movers - red crossbills and pine siskins, whose ranges are described in many field guides as highly irregular, irruptive, erratic or wandering, probably due to fluctuations in food sources.

Long distance migrants undertake migratory journeys that can take weeks to complete and cover thousands of miles. Some 350 species are considered "neotropical" migrants, from "neo" referring to new and the new world of the Americas, and "tropical" defined as the latitudinal region between the Tropic of Cancer in the northern hemisphere and the Tropic of Capricorn in the southern hemisphere.

These birds breed in the United States and Canada and winter in the Caribbean, Mexico, Central America and South America. Neotropical migrants include raptors, vultures, waterfowl, shorebirds, and passerine (perching songbird) species such as hummingbirds, thrushes, warblers, orioles, and tanagers.

Some species do not migrate at all because they are able to find adequate supplies of food throughout the winter in the same place they breed and rear young. Crows, quail and pheasants definitely fall into this category. Some owls and nuthatches might also be permanent residents.

"Songbird Journeys - Four Seasons in the Lives of Migratory Birds," a book by Miyoko Chu, science writer at the Cornell Lab of Ornithology, delves into more detail on bird migration. The following is from a Lab description of the book:

"One of the world's most extraordinary wildlife migrations passes unseen within hundreds of feet of our own neighborhood--the night flights of millions of songbirds. By dawn, these colorful migrants descend to our backyards, urban parks, and forests, either to replenish themselves for the rest of their trip or to settle in for the summer and raise their young.

Until recently, little was known about the lives of songbirds during their travels from autumn until spring. Aided by modern technology, however, scientists have documented mass migrations over the Gulf of Mexico, identified the voices of migrants in the night sky, and showed how songbirds navigate using stars, polarized light, and magnetic fields.

Miyoko Chu explores the intricacies underlying the ebb and flow of migration, the cycle of seasons, and the interconnectedness between distant places. "Songbird Journeys" pays homage to the wonder and beauty of songbirds while revealing the remarkable lives of migratory birds and the scientific quest to answer age-old questions about where songbirds go, how they get there, and what they do in the far-flung places they inhabit throughout the year."

For more information, see http://www.birds.cornell.edu/AllAboutBirds/studying/migration/sbj/document_view


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