I agree with Jeff here. As a general rule studies of have revealed that vagrant passerines etc. seem to be predisposed or hard-wired to some to degree to wander, often on a heading that is 180 degrees off from normal (i.e. Tropical Kingbirds, Fork-tailed Flycatchers) or heading that is the mirror-image of the one they should be on (eastern warblers and other passerines). It has been theorized that this is a built-in survival mechanism that results on some small percent of the overall population straying out of range. Think of them of pioneers. Vagrancy often happens in the utter absence of weather patterns that we assume would support certain types of directional wandering. Each fall vagrant warblers show up along the West Coast regardless of whether there are corresponding easterly or westerly winds.
Clearly, there are instances when birds are collected up in hurricanes and other offshore storm systems and blown near shore or even far inland. But in this case the proposed "blown down the gorge" theory doesn't make a lot of sense. The course of the Columbia River is winding once you get east of what we think of as "the gorge" and it doesn't form a linear conduit that connects directly to places where Eastern Bluebirds occur normally. The other reports from the far west (Cassia County, ID) and in far northern British Columbia are not logically connected to any natural pathway from their home range.
As others have asked, how many of us have ever paid much attention to bluebirds and made sure that every Western Bluebird we assumed were seeing was one? I've never looked twice in an effort to spot an Eastern among the many Westerns I see each year. Frankly, it has not been a potential vagrant that was really on my radar. Shawneen says she has always looked for them, but I think she and Bob Archer are in the minority among the whole of the Oregon birding community. I've never heard anyone speak aloud about looking for Eastern Bluebirds in Oregon or include this species in their predictions of the next 10 new birds that will appear in Oregon. We've surely considered a lot of other possibilities.
From: <obol-bounce...> <obol-bounce...> on behalf of Jeff Gilligan <jeffgilligan10...>
Sent: Wednesday, November 28, 2018 1:15 AM
Subject: [obol] Re: Eastern Bluebird thoughts
> On Nov 27, 2018, at 9:37 AM, Bob Archer <rabican1...> wrote:
> I was thinking about how these birds got to a small field in NE Portland. The TX and AZ birds are resident that do not migrate, I see that CA has no record and one record not accepted, Nevada has no record. So those birds simply do not move. Eastern Bluebirds are scattered all over western Montana. Last week the gorge experienced strong east winds. Idaho has one record from Cassia County (middle of the southern border). Utah has a few. These birds were blown down the gorge and dumped outside the western entrance?
> Bob Archer
I donít think a species like Eastern Bluebird gets blown out of range,as would a seabird for example. I assume that Eastern Bluebirds are slow migrants that donít fly particularly higr and sit out challenging winds rather than fly long distances in the wind.
The fellow who works at the flooring store says he saw them first about two months ago.