December 19, 2012
Macho Male Zebra Finches Fake Their Birdsong For Foreign Females
Brett Smith for redOrbit.com - Your Universe Online
British researchers have found that male finches will use their birdsongs like their human counterpart use an out-of-date Facebook profile picture — to trick a potential mate into thinking they are more physically fit than they actually are.
“Every man wants to cast himself in a favorable light when he meets an attractive female, and we have shown that birds are no different,” said co-author Sasha Dall, an ecologist from the University of Exeter.
“But just like many humans, it seems zebra finch males are unable to dupe females who know them well enough. When the birds were in an established relationship, the female could tell the true condition of a male by his song, and judge whether he would make a good father for her next brood.”
The singing male zebra finches examined in the study use their songs to convey physical fitness as the act of singing requires a good deal of energy. The healthiest birds are understood to be those that are able to maintain a high rate of song for longer periods of time than less healthy birds. And in the process of sexual selection, a robust, healthy bird makes for an ideal mate.
In the study, the research team studied 91 male and 91 female zebra finches from a colony at the University of Bourgogne in France as well as 12 of each sex from the University of Exeter. Each of the birds was examined and rated for its level of fitness.
The researchers then observed and filmed inter-gender encounters between birds that were unfamiliar to each other. The unfamiliar birds were exposed to each other for both short and longer periods of time. They also looked at encounters between male and female birds that were already established mating partners.
During their observations, the biologists looked for signs of courtship and eventually breeding between the finches. They noticed that the male birds sang in the same manner in both the short and long encounters with the unknown females. However, when the males were paired with their mates, the healthiest birds sang at a higher level than those in poorer condition.
“This is the first study to find evidence that the link between male body condition and birdsong differs depending on the context of the encounter with the opposite sex,” said lead author David Morgan, from the University of Exeter. “It could have significant implications for learning more about the evolution of courtship patterns such as birdsong.”
Zebra finches are the most popular finch in Australia, where they are commonly kept as pets. The finches are also widely used for various types of scientific research.
The birds select a mate based on both the color of plumage and quality of song. They tend to breed after large rainstorms, which can happen at any time of the year in their natural Australian habitat.