Don "Back from the Edge" Baccus wrote:

>I think the answer [to Scrub Jay distribution] might lie in a couple of
>directions:
>
>1. Ag development did indeed lead to timber harvest and also clearing of the
> Oak Savannah typically occupied by species like the scrub jay, acorn
> woodpecker, and Lewis's woodpecker.
>
> Decline of the latter species, at least, is partially due to the
> spread of the starling.

I agree pretty much with Don's assessment of the decline of the oak
savanna, but I'll reiterate previous postings of mine that we may be too
hasty in attributing various declines to the ever-maligned starling.
Lewis' Woodpeckers, at least in Washington, were way down in numbers before
the first starlings reached any appreciable populations here. Acorn
woodpeckers are known to be resistant to starling incursion, but they would
surely decline with the diminution of oak habitats, just as Lewis' would.
However, Lewis' were quite common in parts of Washington that lacked oaks,
but they were certainly associated with land that had been partially logged
and thus had plenty of open areas with snags in which to nest. I'd bet
money (no one can prove me wrong, of course) that there were a lot more
flying insects (Lewis' woodpecker food) in this area 50-100 years ago, when
it was a patchwork of forest and cut-over land.

There has been much made of the decline of the Lewis' woodpecker in the
Northwest, but it's difficult to rationalize that with the abundance of the
species at places and times that are optimal for them, as in Klickitat and
Yakima counties in years of good acorn production. They are as common
there and then as I've ever seen them, and my guess is that their
decline--again--rather than being something sinister to contemplate, can be
simply explained by habitat changes. There are probably fewer large trees
producing fewer snags now, even in the interior, than there once were, as
we extend our human domain further and further. Flickers seem to be able
to adapt to this, Lewis' not.

>2. In the case of the scrub jay, it is also true that the species, much
> like the crow, has become much more urbanized in the last 50 years
> (since the War). I think this has largely counterbalanced the
> disappearence of the original oak habitat for this species. I, at
> least, as a kid grew up thinking of this as a city bird...

Scrub jays probably would have declined with the decline of the oaks but
were able to flourish because, like most corvids, they were able to take
advantage of the presence of humans; Lewis' woodpeckers show no such
ability.

>> As the Scrub Jay is the common Jay in the Willamette Valley, along the
>> Washington side of the Columbia, and - indeed - is common in some Olympia
>> neighborhoods, it is apparent that their distribution has changed
>> radically in the past 70 years.
>
>Again - urbanization?

I certainly think so. I also grew up (with many visits to southern
California, where my grandparents and then parents lived) thinking of Scrub
Jays as urban birds.

>> I don't know how much of it is 'competition' and how much is habitat-
>> related. Our Pacific Northwest has had its habitats altered very
>> significantly - even in our short lifetimes, let alone since white
>> settlement. It stands to reason that the bird populations will respond
>> to those changes.

I think this will always be the main cause of dramatic local changes in
bird populations.

Dennis Paulson, Director phone: (206) 756-3798
Slater Museum of Natural History fax: (206) 756-3352
University of Puget Sound e-mail: dpaulson at ups.edu
Tacoma, WA 98416