Date: 6/6/18 10:12 am From: Wayne Hoffman <whoffman...> Subject: [obol] Native North American Breeding Range Expansion into Oregon
One more to think about.
Least Flycatcher - I do not have references handy, but I think was unknown to Gabrielson and Jewett? Then a few summer occurrences and probable (confirmed?) nestings in riparian ares on the east side since the 1970s? THEN - a report from a few years ago that they were breeding in numbers in the Cottonwood plantation along I-84 east of Boardman. Artificial habitat that seems to have been really attractive to them. Then, the plantation was clearcut to make room for the industrial milk factory that is currently in arrears on its waste discharge permits, and mired in bankruptcy court.
It is worth wondering what other birds in Oregon are so dependent on artificial habitats, and what other "rare" extralimitals are poised to take off, given the right agricultural situations.
I have surveyed bird populations in Cottonwood and poplar plantations in the past. They are structurally simple and of course monocultures, but they support abundant insect populations and high densities of a few native birds. Back in the 1990s I surveyed in plantations in Columbia River bottoms from Clatskanie to Cathlamet. In the older stands I found high densities of Swainson's Thrushes, Pacific-slope Flycatchers, and Black-headed Grosbeaks, also decent numbers of Western Tanagers and a few breeding Western Kingbirds and Bullock's Orioles. No cavity-nesters, of course, and few understory birds. 2-3 year-old stands had Song and White-crowned sparrows, and Lazuli Buntings. During fall migration(August - October) they got very little use, compared to nearby habitats with tree species diversity and especially with lots of low cover.