Because the answers are local, and learned from elders, wild cultures can be lost faster than genetic diversity. When populations plummet, traditions that helped animals survive and adapt to a place begin to vanish.
In a scientific article on the vocabulary of larks living in north Africa and Spain titled, "Erosion of animal cultures in fragmented landscapes", researchers reported that as human development shrinks habitats into patches, "isolation is associated with impoverishment". They write: "Song repertoires pass through a cultural bottleneck and significantly decline in variety."
Unfortunately, isolated larks are not an isolated case. Researchers studying South America's orange-billed sparrow found that sparrow "song complexity" – the number of syllables per song and song length – deteriorated as humans continued whittling their forests into fragments. When a scientist replayed 24-year-old recordings of singing male white-crowned sparrows at the same location she'd recorded them, they elicited half the responses they had when first recorded. The birds' responses show that changes in the dialect lead to changes in listener preference, a bit analogous to pop music. And as with humans, preferences can affect whether a particular bird will be accepted as a mate. White-crowned sparrows singing a local dialect become fathers of more offspring than do singers of unfamiliar dialects, indicating females prefer a familiar tune.
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I'm not just talking about a few songs. Survival of numerous species depends on cultural adaptation. How many? We're just beginning to ask such questions. But the preliminary answers indicate surprising and widespread ways that animals survive by cultural learning. Regionally different vocalisations are sometimes called "song traditions" but the more commonly used word is "dialects". More than a hundred studies have been published on dialects in birds. And it's not just birds but a wide array of animals Including some fish.
"Cod particularly," said Steve Simpson of the University of Exeter, "have very elaborate calls compared with many fish." You can easily hear differences in recorded calls of American and European Atlantic cod. "This species is highly vocal with traditional breeding grounds established over hundreds or even thousands of years." Many fish follow elders to feeding, resting and breeding areas. In experiments, introduced outsiders who learned such preferred locales by following elders continued to use these traditional routes after all the original fish from whom they learned were gone.
Cultural survival skills erode as habitats shrink. Maintaining genetic diversity is not enough. We've become accustomed to a perilous satisfaction with precariously minimal populations that not only risk genetic viability of populations but almost guarantee losing local cultural knowledge by which populations have lived and survived.
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