Hard times make birds better singers
A hostile environment and inconsistent weather may explain why some birds become better singers than others, according to a new study.
The researchers also conclude that it leads to superior learning and mating skills.
The research, published in the journal Current Biology, is based on a large-scale study of mockingbirds in different habitats.
"As environments become more variable or unpredictable, song displays become more elaborate," says Dr Carlos Botero, a researcher at the US National Evolutionary Synthesis Center in North Carolina.
"Survival and reproduction become more complicated when weather patterns are unpredictable because you don't know when food will be available or how long it will be around," he says.
And for female birds, "the consequences of picking a mediocre mate are magnified in harsher climes."
The researchers searched sound archives around the world and travelled the southern hemisphere to tape bird songs in the wild, recording nearly 100 tracks from 29 mockingbird species.
The team later used computer programs to convert each sound recording into a sound graph and compared the patterns to a database of temperature and precipitation records.
According to Botero, male mockingbirds sing mainly to impress mates, so during harsh times they use superior singing skills to suggest that they are a good catch.
He says males that sing more complex songs also "tend to carry fewer parasites, and have offspring that are more likely to survive."
Songbirds are not born knowing how to sing, and have to learn their songs over time.
Botero and colleagues believe that this song-learning ability is a sign of broader learning ability.
They suggest that natural selection may lead to the birds not only learning from each other, but may also lead to the evolution of more complex songs.
"Birds that sing better are telling others, at least indirectly: Hey, I'm a good learner," he says.