Polly Doesn’t Want A CrackerPosted: June 7, 2012
Every morning and evening in the Amazon, wild parrots gather on exposed cliffs like this one to engage in geophagy, a fancy word for eating dirt. As the parrots scrape and lick the clay-rich soil, they socialize — loudly. “They’re all screaming their heads off,” says U.C. Davis conservation biologist James Gilardi. The smooth-textured clay, he says, acts like a water softener in the parrots’ guts, helping to neutralize the toxins the birds ingest from eating unripe and even poisonous seeds.
Gilardi studied two parrot “clay-licks” in Peru for his Ph.D thesis, and now runs a conservation organization called the World Parrot Trust. Despite their popularity, parrots remain mysterious in the wild. Geophagy is just one example of a behavior that has been largely overlooked. Gilardi studies wild parrots in the hopes of conserving them in their native habitats and allowing people to take better care of them as pets. This week, his team published new evidence in PLoS ONE showing that parrots seek out bitter, toxic foods other animals won’t touch.
To catch the birds snacking, Gilardi and his team spent several summers walking through Manu National Park in the Peruvian Amazon. They spent up to ten hours per day watching from the ground for parrots rustling in the canopy and listening for squawking cries or the sound of falling fruit. When they found the parrots, they wrote down the kind of tree the birds were in, and noted what dropped on the ground. They also climbed the trees to collect samples, and sat in the canopy watching the birds fly and forage. They wanted to know whether the birds preferred seeds or fruits, how thoroughly they “demolished” their food, as Gilardi puts it, and whether they gobbled up ripe or unripe fruit and seeds. Parrots are messy eaters, but it was soon clear that the birds were going after unripe seeds. Many of these are protected by bitter, potentially toxic substances like alkaloids, found in substances like hemlock and strychnine.
The parrots weren’t just swallowing seeds and pooping them out intact, like many animals do. Instead, they were digesting them. This wasn’t a surprise, says Gilardi. Large macaws can destroy softball-sized seeds with their beaks, cracking shells that would take a monkey many blows with a rock to break apart. “Anyone who’s ever watched parrots in the wild knows that they are destroying seeds.” What surprised him was the toxicity of the seeds they were digesting: “A lot of the things they’re eating are pretty nasty.” Sometimes they would see a tree full of fruit which other birds or animals shunned. Then the parrots would arrive and “just plough through” it.
In addition to detoxifying their systems by eating clay, Gilardi says that parrots’ livers and other aspects of their physiology are better equipped than ours to deal with poisonous substances. Although parrots are one of the most endangered bird species in the world, parrot conservation almost never has anything to do with food. “It’s one less thing to worry about.”
More often the threat is habitat destruction and capture. “Parrots are often threatened by something local to them,” says Gilardi. Parrot trafficking for pet sales, in addition to the clearing of tropical forests, threatens roughly more than one in four parrot species — about 95 out of 360 total. Although the World Parrot Trust doesn’t condemn bird-keeping, it works to protect parrot habitat, eliminate illegal and unsustainable parrot trafficking, and help pet owners care for their birds correctly. “If we’re going to do this,” he says, “let’s do it right.”
People tend to feed parrots things people like to eat: cereal crops that have been heated up, cooked, and shaped into pellets. They feed them ripe fruit when a parrot might actually prefer something as astringent as an unripe persimmon. “It’s a huge problem,” says Gilardi. He hopes that people will consider that their backyards might be a better place to find parrot food than the grocery store.
Photo credit: Wikipedia Commons