Biology Reference
In-Depth Information
2
Fig. 7.5
Malte
Andersson's classic
experiment
showing how male
tail length in
long-tailed
widowbirds
influences female
choice. Top: Before
experimental
manipulations,
there was no
significant
difference across
the four groups in
the mean number
of nests per male
territory (a measure
of the number of
females attracted).
Bottom: After
experimental
manipulation,
males with
elongated tails
attracted more
females compared
to shortened-tail
males and controls.
The drawing
shows the male
display flight. After
Andersson (1982).
Reprinted with
permission from
the Nature
Publishing Group.
1
0
2
1
0
Shortened
Control
Tail treatment
Elongated
oestradiol to make them sexually active, they were more responsive to playbacks of
larger repertoires than to small repertoires (Fig. 7.6b).
In some cases, males have multiple ornaments - some for attracting females and some
for deterring rival males (Box 7.2).
Female choice for
more complex
songs
Why are females choosy?
Many other studies have now demonstrated female choice (Andersson, 1994). But why
do females choose? Once again, Darwin did not provide an answer other than suggesting
that animals, like humans, had an aesthetic sense. During the last four decades many
