Newsgroups: rec.birds
Path: utzoo!rising
From: rising@utzoo.uucp (Jim Rising)
Subject: Foster Parents
Message-ID: <1988Apr5.141503.5406@utzoo.uucp>
Organization: U of Toronto Zoology
Date: Tue, 5 Apr 88 14:15:03 GMT

Someone else can answer your question better than I, Joyce.  But it
is adaptively disadvantageous to raise offspring that you have "not
contributed genes to," and thus there is selection to evolve mechanisms
to avoid doing it.  One would suppose that that would never happen
naturally in ospreys.  Thus, there has been no selection for avoidance
mechanisms.  However, it probably is a common "problem" for ungulates
and other farm animals.

--Jim Rising
-- 
Name:   Jim Rising
Mail:   Dept. Zoology, Univ. Toronto
        Toronto, Ontario, Canada    M5S 1A1
UUCP:   {allegra,ihnp4,linus,decvax}!utzoo!rising