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  • Many migrants will decide to become immigrants

    Migrants join residents, but which are which?
  • The first bits of robin song are leaking out even though spring is a long way off. A sun break on an otherwise bleak winter afternoon elicits a subdued song or two. It's just a taste. The short phrases promise rich evening solos when the apple trees are in bloom.
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  • The first bits of robin song are leaking out even though spring is a long way off. A sun break on an otherwise bleak winter afternoon elicits a subdued song or two. It's just a taste. The short phrases promise rich evening solos when the apple trees are in bloom.
    I wonder whether this is the robin that will claim my yard this year. Probably not. The small flock rises out of the pyracantha hedgerow, where many unseen birds had been silently feeding, and strikes off for a roost with thousands of others along Bear Creek or the Rogue River, taking my reluctant singer with it.
    This bird was a migrant likely from British Columbia or even Alaska visiting the Rogue Valley to sample the madrone berries, crabapples and pyracantha berries. By March it will begin the long adventure north, perhaps to a stream-side woodland near Kamloops or Dawson. Wherever its destination, this robin will not be serenading me in April.
    As daylight loses its strength in the afternoon, more flocks from throughout the foothills and backyards pass overhead completing their daily routine. And yet, there is still one bird left in the yard. It calls a couple of times from high in the pine but shows no desire to join the commuters.
    Is this the robin that will nest in the elm or apple tree in my yard? It may very well be. At 42 degrees north latitude (the Oregon/California line), we are far enough south where northern migrants join us for the winter, but because the climate is relatively benign, at least some of our breeding birds find no reason to move along.
    Robins aren't the only northern migrants who join our resident birds. Some red-tailed hawks travel great distances, including from Alberta and Alaska, to winter here. Yet on a warm December day, it is not uncommon to see a bird take a stick to its nest and rearrange the furniture a bit. Nothing serious, but enough to indicate that the resident birds are still with us.
    It is clear that many of our wintering northern flickers come from distant places. The occasional bird shows traits of both the "yellow-" and "red-shafted" forms, betraying its origin as the Canadian Rockies where the two meet. A red crescent on the back of the head, maybe a black moustache and sometimes even yellow in the wings and tail provide clues as to its origin. But this doesn't tell us that any of the birds wintering here also remain to breed. However, I suspect at least some do.
    Studies have shown that some species such as fox sparrows tend to leapfrog others. Birds breeding farthest north tend to winter farthest south. Southern breeding birds may not migrate at all. I suspect the Rogue Valley is in that portion of the country where many of our breeding birds find the valley hospitable enough to hang around all year. And the leapfroggers? Well, I guess they haven't read the research or just don't have what it takes to make it over the hill and into California. It makes for abundant birds on a rather dreary winter landscape.
    Such are my musings on a chilly and sometimes wet winter day. I just wish the winter birds came with luggage tags.
    Stewart Janes is a biology professor at Southern Oregon University. He can be reached at janes@sou.edu.
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