Cowbirds frequently parasitized the Red-winged Blackbird. When I
was studying nesting sucess of birds in Kansas tallgrass prairie, the
Red-wings were the second most common host after the Dickcissel. Both
Dickcissels and Red-wings are capable of raising their own chicks as well as
cowbird chicks. In Kansas, I observed a female Dickcissel (who receives no
help from the male) feed two cowbird and three Dickcissel chicks. All but
one cowbird left the nest; it stayed behind and eventually starved in the
nest. Red-wings are also capable of raising several cowbirds with their own
young.
Ejection of cowbird eggs is dangerous for the host species. Host
eggs may be broken during cowbird egg ejection. In addition, the Red-wings
run the risk of ejecting their own eggs which are similar in color to the
cowbird's egg. Where the cost of raising a cowbird chick is small, the host
parent gains little by ejecting the egg and the cost of ejection may be
greater than the cost of raising the cowbird.

At 21:05 25/8/97 -0400, you wrote:
>Michael Price wrote: >. At Iona this summer I observed
>a female Red-winged Blackbird, an unlikely host
>species, feeding a juv cowbird at the Iona
>settling ponds >
>
>Michael, in researching brown-headed cowbirds for an
>educational presentation, I learned that red-winged
>blackbirds are quite regularly parasitized by cowbirds.
>The interesting thing is that they are among the few
>species that would be physically able to eject
>cowbird eggs without puncturing them (thereby
>messing up the nest), but do not choose to do so.
>Their populations appear to be withstanding the
>threat nicely also. Perhaps there is plenty of chow
>to go around, or their own nestlings are more
>competitive.
>
>Chris Maack
>Anchorage, AK
>CMaack at compuserve.com
>
>
>
Deb Beutler
Department of Zoology
Washington State Univerisity
Pullman, Whitman Co., WA
dbeutler at wsunix.wsu.edu