Mennill and his colleague Amy Rogers measured eastern whipbird recordings from 16 different populations along the east coast of Australia. For each of the 112 birds that they recorded, they measured the song's number of syllables, the length of the first syllable, the highest and lowest frequency of the last syllable, the time between these frequency extremes and other characteristics.
The vast majority of female recordings showed variations on each of these criteria, but male songs were all virtually identical.
Findings were published in a recent issue of the
Journal of Avian Biology.
In the wild, the males and females sing duets. Males initiate the duet with a long whistle and an ear-splitting "whip crack." Females then respond with a sharp "chew chew."
"In my opinion, the 'whip crack' sound might be the most extraordinary note produced by any beast in the animal kingdom," Mennill told Discovery News. "It involves a pure tone that ascends or descends extremely rapidly across a very broad frequency spectrum. It is possible that this note is difficult to perform, and that females may favor males who are capable of executing this difficult note effectively."
While males must sing their hearts out for females, both males and females engage in their own same sex singing contests, which are not unlike popular televised competitions for human singers.
For these contests, usually each bird will perch itself near its territory boundaries. They then sing back and forth, trying to match the song sung by the opponent. Often the songs wind up overlapping like dialogue in a Robert Altman film.
Peter Slater, a professor of natural history at the University of St. Andrews in Scotland, told Discovery News that he agrees with the findings.
Slater said that "the real surprise here is the stereotypy (repetitive sameness) of the males ... . In some other birds, females appear to choose mates on the basis that they perform a song that is quite hard to produce. I like the idea that the whipcrack may be such a phenomenon and this might explain its very unusual stereotypy."
In terms of accents, he said that geographical variations, or dialects, are found in other songbirds, whales, seals and primates.
Mennill suggested that females may benefit by sharing songs that are similar to those of nearby females. While these benefits remain unclear, it is possible that the singing helps to somehow coordinate reproductive activities.
Male eastern whipbirds perhaps might have evolved accents too, if it were not for their impressive "whip crack" song with its stunning finale.
"Females may prefer males who 'whip it good,'" said Mennill.
Name: Eastern Whipbird (
Psophodes olivaceus)
Primary Classification: Passeriformes (Perching Birds)
Location: Eastern Australia
Habitat: Wet habitats like rainforest, eucalypt forest and dense scrub near rivers.
Diet: Insects and other invertebrates.
Size: Averages 11 inches in length and 2 oz in weight.
Description: Dark olive-green; gray-white belly; black head and breast; broad, white face patch; black crest.
Cool Facts: Its characteristic call is sung as a duet, the male making the drawn out "whip crack" sound followed by a sharp "chew chew" from the female.
Conservation Status: Common
