Cultural knowledge, passed from animal to animal, is key to how species adapt to change in the world around them
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Sam Williams' in Costa Rica rewilds captivity-hatched fledgling scarlet and great green macaws. But introducing young birds into a complex forest world – bereft of the cultural education normally provided by parents – is slow and risky.
For 30 years or so scientists have referred to the diversity of life on Earth as "biological diversity", or just "biodiversity". They usually define biodiversity as operating at three levels: the diversity of genes within any particular species; the diversity of species in a given place; and the diversity of habitat types such as forests, coral reefs, and so on. But does that cover it? Not really. A fourth level has been almost entirely overlooked: cultural diversity.
Culture is knowledge and skills that flow socially from individual to individual and generation to generation. It's not in genes. Socially learned skills, traditions and dialects that answer the question of "how we live here" are crucial to helping many populations survive – or recover. Crucially, culturally learned skills vary from place to place. In the human family many cultures, underappreciated, have been lost. Culture in the other-than-human world has been almost entirely missed.
We are just recognising that in many species, survival skills must be learned from elders who learned from their elders. Until now, culture has remained a largely hidden, unrecognised layer of wild lives. Yet for many species culture is both crucial and fragile. Long before a population declines to numbers low enough to seemthreatened with extinction, their special cultural knowledge, earned and passed down over long generations, begins disappearing. Recovery of lost populations then becomes much more difficult than bringing in a few individuals and turning them loose.
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Many young birds learn much by observing their parents, and parrots probably need to learn more than most. Survival of released individuals is severely undermined if there are no free-living elder role models. Trying to restore parrot populations by captive breeding is not as easy as training young or orphaned creatures to recognise what is food while they're in the safety of a cage – then simply opening the door. "In a cage," Williams says, "you can't train them to know where, when and how to find that food, or about trees with good nest sites." Parents would normally have done exactly that.
A generational break in cultural traditions hampered attempts to reintroduce thick-billed parrots to parts of south-west America, where they'd been wiped out. Conservation workers could not teach the captive-raised parrots to search for and find their traditional wild foods, skills they would have learned from parents.
Landscapes, always complex, are under accelerated change. Culture enables adaptation far faster than genes alone can navigate hairpin turns in time. In some places, pigeons and sparrows have learned to use motion-sensors to get inside enclosed shopping malls and forage for crumbs. Crows have in some locales learned to drop nuts on the road for cars to crack. In at least one area they do this at intersections, so they can safely walk out and collect their cracked prizes when the light turns red and the cars stop. They've developed answers to the new question: "How can we survive here, in this never-before world?"
