[Richard Crowley]

"bill" wrote ...
You are right about the bass, and a bare speaker does pick up the wind
pretty good. What was strange about that setup was that a bug crawling
on the speaker surface was LOUD.

You may be on to something there (for insects, at least).
But doesn't seem very well-suited for birds. What about
an ordinary (and ultra-cheap) electret mic capsule in some
sort of weather-resistant enclosure like those louvered
little round housings they use for weather station thermal
sensors?