Hi All
A study done in 1977 in Washington by Smith & Atkins found a 1.9% parasitism
rate of Brown-headed Cowbirds on Bushtits.

This statistic comes from Catherine Ortega's book, Cowbirds and other brood
parasites. It includes a table summarizing parasitism rate studies.
Unfortunately it is too lengthy a table for a Tweeters post. I do recommend
the book. Cowbirds turned out to be much more interesting and complex than I
had thought.

Cheers
Gail Spitler
Johnsons Landing, BC
spitler at wkpowerlink.com