Tweets,

Dennis wrote:

>Brood parasitism is undoubtedly one of the major sources of mortality on
>passerine birds in this area.

One stop on the Kirkland's Warbler Tour in Mio, Michigan was a visit to a
cowbird trap that has been successfully used to control brood parasitism
on the Kirkland's Warbler.

The cowbird trap was designed for this recovery effort some years back.
It's a large screened cage that is big enough to standup in, about 8 by10
feet. The cowbirds come in through a top screen that has a hole large
enough for them to drop through. They are attracted by female cowbird
decoys, food, and water.

If I remember correctly, there are 62 traps on 115,000 acres. Two people
go around daily to release birds like blue jays and kestrals and remove
the non decoy cowbirds. The cowbirds are gassed and used for further
research when possible.

This has apparently been a very effective cowbird control and is copied
in other places now.

Ileen Weber
Seattle, WA
duncanweber at seanet.com