Singin’ in the Rain
Birds that live with fluctuating weather are more complex singers. That’s the conclusion of a study by researchers from Australian National University and the National Evolutionary Synthesis Center in North Carolina, who analyzed recordings from 400 male birds representing 44 species of North American songbirds. After studying spectrograms (sound graphs) of twitter, warbles, chirps, and trills, the researchers found that the more dramatic the seasonal swings in precipitation in a given habitat, the more variable a bird’s song. The same goes for geographic variation: If a bird’s habitat includes differences in precipitation, the avians up their sound game.
When you consider that birds often arrive in their breeding grounds when vegetation is sparse, only to experience them becoming densely vegetated over a matter of weeks, it all makes charming evolutionary sense. Acoustic conditions change as vegetation changes. The “birds that have more flexibility in their songs may be better able to cope with the different acoustic environments throughout the year,” said study co-author Iliana Medina.
Desert cardinal image by iStock/Dr-Strangelove
Reed McManus is a senior editor at Sierra. He has worked on the magazine since Ronald Reagan’s second term. For inspiration, he turns to cartoonist R. Crumb’s Mr. Natural, who famously noted: “Twas ever thus.”