On Friday, 26 May, Dennis wrote:

>Crows were the predator in both cases. [snip]

>I have noticed this spring that crows have a search strategy, probably
>something for the breeding season. They fly slowly and steadily, often
>well below the canopy, and you can see them performing visual sweeps. I'll
>bet they are looking for bird nests.

I'll put in a word for the ravens -- they appear to use the same strategy.
A couple of years ago I watched the systematic predation of a varied thrush
nest at a campground in Oregon. First evidence was the
"whoosh-whoosh-whoosh" sound of raven wings as a bird flew methodically
through the trees at about half canopy height or a little below. The next
clue was the racket created by the distressed parents. The thrushes
apparently had a nest on a conifer branch which to my non-avian eyes seemed
to be well-camouflaged by a tangle of branches. Three times I observed the
raven landing at the nest and quickly flying back out, carrying a smallish,
light-colored object in its bill. After the third trip the raven did not
return (presumably because the nest was then empty) and the thrushes
gradually settled down.

>This has really become clear only in the past decade--that our
>changes in the landscape overwhelmingly favor a bunch of species (both
>native and introduced) that compete with or prey upon many of the other
>native species, suddenly more vulnerable to the same natural processes to
>which they have been adapted all along but perhaps at greater intensity in
>these settings.

Having spent a few years being involved with marbled murrelet research,
this is a topic of interest. Corvids are known predators of murrelet nests.
Yet, as a corvid- (and thrush-)lover, it is difficult for me to attach some
emotional "blame" to them (or any other natural predator) if one of the
extremely-small-sample-size, difficult-to-FIND murrelet nests "fails" due
to predation. Our massive alteration of the forest landscape is at least as
much under suspicion/fault if it tips the ecological balance in favor of
the more adaptable predator species. It will be interesting to see the
results of the research John Marzluff is beginning this year on the Olympic
Peninsula.

>Tweeters would make a good forum for other personal accounts of success or
>failure of nesting attempts in peoples' yards.

As for "yard nests," I can report that our "bird diversity-challenged"
house and yard are supporting two house sparrow nests, a bumblebee nest,
and that starlings have apparently ousted a pair of violet-greens from a
hole by the bathroom window.

Janet Hardin
Port Townsend, WA
<wings at olympus.net>