One advantage of studying birds at this site was not having to account for factors like pollution and birds being struck by vehicles, issues often present at other noisy sites, such as next to a highway.
The team compared populations living near noisy compressors with those living near quiet ones, and found that both species of birds are just as common at the two sites. However, they adjusted their songs in different ways. The song comprises multiple notes in a short whistled phrase.
“Plumbeous vireos raised the pitch of the lowest part of their song, while grey vireos raised the pitch of the highest part of their song,” Francis said.
At the noisier sites, the plumbeous vireo songs became shorter, while the grey vireo songs got longer. “Grey vireo songs in noisy sites were nearly one and a half times as long as their counterparts in quiet sites,” Francis said.
The team concluded that the ability to alter songs may help some species live in noisy areas. However, as the two closely-related species coped with the noise in different ways, it may be difficult to predict how various bird species adapt their songs in an increasingly noisy world.
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