You're probably right, Deb -

>
I don't think being in the same taxomic family has anything to do with it.
Bullock's and Baltimore Orioles (also icterids) eject cowbird eggs on a
regular basis. Other icterids, such as grackles and the Yellow-headed
Blackbirds also eject cowbird eggs.
Deb Beutler>

Thought I'd tell you a sort of sweet viewpoint on
nest parasitism. My sister is an anthropologist who
has worked in New Guinea, and who became a birder
while there. She knew there were some species that
laid their eggs in other species' nests, so she asked
the villagers what the story was on that. They told her
that they knew some types of birds (the nest parasites)
were unable to have young of their own, but that every
so often a different type of bird would feel sorry for
them and lay an egg and raise a chick for them.

Chris Maack
Anchorage, AK
CMaack at compuserve.com