Birds that live with varying weather sing more versatile songs
Melbourne: Birds that sing versatile songs may be better able to cope with fluctuating weather, Australian researchers have said.
A study done at Australian National University and the National Evolutionary Synthesis Center found that North American songbirds that live with fluctuating weather ensure that their songs are heard regardless what the habitat they are live in.
"Birds that have more flexibility in their songs may be better able to cope with the different acoustic environments they experience throughout the year," co-author Iliana Medina of Australian National University said.
The researchers analysed song recordings from more than 400 male birds spanning 44 species of North American songbirds a data set that included orioles, blackbirds, warblers, sparrows, cardinals, finches, chickadees and thrushes.
Computer software was used to convert each sound recording a medley of whistles, warbles, cheeps, chirps, trills and twitters into a spectrogram, or sound graph.
Like a musical score, the complex pattern of lines and streaks in a spectrogram enable scientists to see and visually analyse each snippet of sound.
Combining this data with temperature and precipitation records and other information such as habitat and latitude, they found males that experience more dramatic seasonal swings between wet and dry sing more variable songs.
"They may sing certain notes really low, or really high, or they may adjust the loudness or tempo," co-author Clinton Francis of the National Evolutionary Synthesis Center said.
The Pyrrhuloxia or desert cardinal from the American southwest and northern Mexico and Lawrence's goldfinch from California are two examples.
In addition to variation in weather across the seasons, the researchers also looked at geographic variation and found a similar pattern.
The study also found that species with striking colour differences between males and females also sing more variable songs, which means that environmental variation isn't the only factor, the researchers say.