A previous study had shown that the most intense wing-spread displays are directed at other males and are used to signal strength and establish position in the birds's social hierarchy. Female cowbirds may not like intense displays because they are generally used by males as aggressive signals.
"She may be frightened; she may be threatened by these more intense displays," O'Loghlen said.
This audiovisual research is still at an early stage and there are many questions yet to be answered about these displays.
"For example, why do males bother to display at all when they sing to females?" asked O'Loghlen.
A possible answer may be the presence of light-colored feathers under the wings of younger male cowbirds. Older males are preferable as mates to female cowbirds, possibly because they are likely to have better quality genes, having survived longer. Females may require males to display to them so that they can tell if a "suitor" is a young or older male. When a male suitor displays, he spreads his wings, showing the age-revealing color of his under wing feathers.
Brown-headed cowbirds are among the most-studied species of songbird. They are brood parasites, laying their eggs in other birds's nests, and leaving their young to be raised by their foster parent "hosts." In some cases, this can have drastic consequences for the host parents, as their own young may die when the cowbird chick outcompetes its adopted siblings for food.
The next steps for the researchers include looking for reasons why females respond to these male displays, and how males develop their display skills.
|Contact: Sonia Fernandez|
University of California - Santa Barbara