Date: 9/28/19 10:40 am
From: <t4c1x...>
Subject: [obol] some thoughts on bird distribution

One of the things, which makes birding so much fun, is the fact bird distribution is not static. Over time it evolves, and our comprehension of birds, their ranges and their movements evolves with it. When I was young, the accepted authority of birds and their ranges within our state was Garbrielson and Jewett's Birds of Oregon . It was a compilation of the records of birds in Oregon, based upon the specimens collected by early ornithologists and those of the authors during their travels across the state under the auspices of the Biological Survey (Later to be known as the US Fish and Wildlife Service). The paucity of out of range birds recorded in that volume speaks loudly of the comprehension of bird distribution at that time. As a matter of fact, Jewett was reportedly known for dismissing reports of out of range birds with the terse comment, "Possible, but not probable."
Just because our comprehension of these things has changed dramatically since that time does not mean we should dismiss the value of this earlier work. It forms the data base from which we are able to judge some of the changes which have occurred, not only in bird distribution, but in our comprehension of it. Thanks to better optics, better field guides, better modes and opportunities of travel, a ten thousand fold increase in field observers with better means than a shotgun for validating records and quicker and better means of communication, that which is possible now cuts a much wider swath into the realm of the probable.
At the same time, a cautionary note is in order. When I first began birding off the farm back in the 1970's Harry Nehls warned me to always consider the possibility of an unusual appearing common bird, before jumping to the conclusion it was some out of range rarity. It was a warning, which is very much applicable today. After all, birds are called rare because they occur with great infrequency.
Having stated these things, I can now address some of the more obvious changes in bird distribution, which have occurred in Oregon just within the past forty years. No one blinks and eye now at reports of Anna's Hummingbird, Black Phoebe, Red-shouldered Hawk or White-tailed Kite. Forty years ago,the report of any of them would have caused excitement among birders. As a matter of fact, White-tailed Kite is the only species of bird for which Gabrielson and Jewett included in their book on the basis of a sight record, and that sighting was their own. They would have rejected it, had the report come from another source. Tropical Kingbird was not included in Birds of Oregon. Neither were about half the shorebirds, which have been documented as occurring in the state. There have also been a great many other species, which have showed up here, which would have been considered out of the realm of possibility some years back. Is this because bird distribution has changed? Or it is because of the tremendous increase in the number of people looking at birds? Probably a bit of both. Were it not for the fact there are many people watching, such things as Red-flanked Bluetail, Dusky Thrush, Little Bunting and Great Crested Flycatcher would have passed through our state unnoticed. The fact they were here strongly suggests the possibility of the occurrence of other species once thought impossible.
Birders heard of such rarities from a variety of sources. Some reports came through telephone hotlines, some through OBOL, more recently, some through e-bird. Not everyone prefers the same source. I have never paid any attention to e-bird, and frankly have no interest in it. Others seem to think it is the greatest thing since sliced bread. Birding has room for personal preference. Maybe even unscientific people like me can now and then find and report birds others might wish to see. Maybe the people with closest ties to Cornell can too. Oh, I have to apologize ahead of time, but I can't resist a tongue in cheek comment. Possible but not probable.

Darrel

 
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