Parrots are famed for their ability to mimic sounds and now
researchers have used 'virtual mates' to discover if female parrots
judge male contact calls when deciding on a mate. The research,
published in Ethology, challenges traditional understandings
of the difference between birds 'songs' and 'calls'.
Parrots are among the few species of bird to have developed the
ability to quickly learn and mimic new sounds, but the evolutionary
reason for this ability is little understood. The Californian based
team used a species of budgerigar to discover if the ability to
mimic new calls is linked to courtship and mate choice.
"We wanted to know whether a female budgie pays attention to a
male's call when she first meets him and if she uses that
information when deciding to mate," said senior author Dr Nancy
Burley from the University of California. "If so the question is:
are females attracted to males that produce calls similar to her
own?"
The problem facing the team was that because budgerigars are
quick vocal learners a male presented with a female will quickly
adapt their call to imitate the female. For the study to be
successful it was crucial that the female was able to hear and
evaluate the male's call before the male had the chance to adapt
his call.
To get around this problem the team developed 'virtual mates' by
installing a series of monitors showing videos of male budgerigars
dubbed with different calls. Each monitor had a pressure activated
perch which would start the clip when the female landed on it.
In each experiment a female was presented with two monitors,
each playing the same video but one had been dubbed with a call
similar to her own. Budgerigars are intelligent and highly visual
animals, yet the females in this experiment readily interacted with
the video images as if they were live males.
The results revealed that female budgerigars are attracted to
males which produce calls similar to their own call but increase
further in similarity during courtship.
Traditionally biologists have focused their research on song
birds and it is well established that songs are used by these
species to attract mates and defend territory. Researchers have
assumed that 'calls' differ to 'songs," however this research
challenges that traditional assumption.
"In our study females listen to variations in calls and use that
information as a basis for mate choice. This suggests that songs
and calls may not be the different categories they have always been
thought to be", concluded Burley. "While we don't yet fully
understand 'why parrots parrot', we now know that the answer to
this question parallels, in some respects, that of 'why birds
sing'."
SOURCE