The image on
the left depicts an adult male cowbird singing an undirected song during the
breeding season. This male’s history is typical of many birds used in our
studies. He was captured as a wild adult male in the summer of 2000. He
participated in two aviary experiments where he mated successfully and in
the summer of 2002 he was released. Birds that have resided in aviaries make
the transition to the life of a wild bird successfully. Banding studies we
have conducted reveal that birds released in the summer frequently reappear
at the lab the following year after having migrated south for the winter.
The image on
the right depicts an adult female cowbird. She was captured as a juvenile in
the summer of 1999 when she was approximately 50 days old. She has
participated in a number of aviary studies where she has bred successfully.
She currently is still in the lab and is serving as a mentor to juvenile
females. Young birds learn a great deal from adults from how to forage to
how to communicate. In this case, NY is serving as a mentor to juvenile
birds that were hand raised from the egg. In this way, we are able to have a
great deal of control over the socialization process of the young.
The image on the left depicts three female cowbirds.
Females use subtle visual signals to communicate with one another and with
males. Thus, what may appear to be three females doing little may well be
three females reacting to each others visual signals, as well as the
behavior of other birds in the area. It is quite possible that one way
females learn preferences for specific males is by watching other females
reactions to males vocal and social behavior. Recent studies in our lab
indicate that females are very competitive among themselves for the
attention of males and there may be many parallels between the development
of female preferences and the development of male song production.
The image on the right depicts four male cowbirds
singing to one another. This communicative interaction is of great
significance to the establishment of male social order but also appears to
be a very important way for males to stimulate and attract female cowbirds.
These two photographs are instructive of gender differences in the nature of
communication in this and many species. The male communicative
behavior is obvious, competitive, and can be overtly aggressive. The female
behavior is subtle, and difficult to observe. This is one reason why much
more is known about development and function of male communication. In the
end, much of the male behavior is designed to impress the female.
|In the sequence above, a male sings a series of songs to a
female, which elicit a copulation solicitation posture. The male then
maneuvers around the female and copulates with her.
Time-frequency spectrograms made using Igor Pro and BSound software written by
BSound is available at
This is a spectrogram of the actual song
used to elicit a female copulation solicitation posture followed by a series
of whistles that are sometimes produced when the male mounts the female. In
the far left of this spectrogram the song is labeled as well as the
introductory notes, which trigger the solicitation posture in the female.
The whistle sequence is also labeled. High-ranking males use the whistle
sequence much more than low ranking males who may frequently use no whistle
advertisement at all.
BABIES BETWEEN 10-15
BABIES BETWEEN 20-25
These baby cowbirds were hand reared from the egg. The
eggs were collected from nests, which we placed in aviaries during the
breeding season. We place fake eggs in the nests, which encourages the
females to lay their eggs in these nests. These baby birds will be raised in
our aviaries where they will choose mates and breed in the following spring.
After microsatellite parentage analysis is performed to determine their
parents, we will be able to investigate group and individual level effects
on reproductive success and the quality of the young produced. Recent work
indicates that the reproductive success of the individual cannot be
predicted without an understanding of group level social effects.
MORE 20-25 DAY OLD BABIES
68-85 DAY OLD BABIES
AN ALBINO BABY