>With the bodies confined to the pavement, I have to assume that the
>mortalities were caused by cars. But why this one very localized spot,

Bank swallows nest in dense colonies, so presumably they're all from
the same colony. I've seen bank swallows swarm in fairly tight-knit
groups at their colonies, and if something were to kill a bunch all
at once in such a situation you'd expect a concentration such as
you describe.

>and why such large numbers of dead birds?

It seems strange.

- Don Baccus, Portland OR <donb at rational.com>
Nature photos, on-line guides, at http://www.xxxpdx.com/~dhogaza