The Secret Lives of Parrots

When a scarlet macaw swoops into the Tambopata Research Center to steal your pancake, it’s probably not the first hardship you’ve suffered that morning. You’re in the middle of a jungle in southeastern Peru, after all. First, you were woken with a jolt at 5 a.m. by the croaking call of a red howler monkey. Shortly thereafter, hundreds of screeching parrots ensured you didn’t doze off. And don’t forget the oppressive humidity!

The Amazon rainforest is one of the most biologically diverse places on Earth. But the main reason scientists and volunteer researchers visit Tambopata is to study the region’s birds. More than a dozen species gather on the clay banks of the Tambopata River, which can reach up to 100 feet high. On the banks, you’ll see small birds like dusky-headed parakeets and larger ones like toucans. But parrots—especially macaws—are the flashiest and most frequent visitors.  

Scientists have been researching Tambopata’s macaws since the early 1990s. The area’s parrot population had been plummeting, and they wanted to understand the birds’ low reproductive rates. Scientists started a program to track all aspects of the parrots’ lives. They count the number of birds on the clay walls. They climb trees to monitor the parrots’ nests and to perform check-ups on the growing chicks. But the biggest unsolved mystery is: Why do hundreds of parrots flock to the clay walls in the first place?

Donald Brightsmith is the director of the Tambopata Macaw Project. He first came to Peru while getting his Ph.D. “There are so many different species,” he says, “and so many questions.” He’s returned to Peru for the past 23 years to find the answers.

But he’s still trying to answer the clay question. When perched on the clay wall, the birds break off pieces with their powerful beaks. Then they fly off to nearby trees to snack on the clay chunks. But there is no obvious reason for this behavior, because there’s plenty of food in the surrounding jungle.

For many years, scientists thought the birds ate the clay to remove toxins from their bodies. Sometimes the seeds and skins of otherwise nutritious foods they eat contain chemicals toxic to parrots. But Brightsmith has a different theory: “It’s a source of dietary sodium,” he says. “I do not believe that toxins are driving clay-lick use.”

Birds, like all animals, require salt. When any animal has low sodium levels, it craves any source of salt it can find. For example, a human who lost salt in a sweaty workout might grab a bag of pretzels. For some types of butterflies, it’s drinking salty crocodile tears. For Tambopata’s parrots, Brightsmith thinks it’s eating clay.

The clay has about twice the salt content as a slice of Swiss cheese. Brightsmith believes it makes up for a lack of sodium in the rest of the birds’ diets. The parrots’ diet is varied, including seeds, nuts, fruits, and vegetation, but contains little sodium—about half the sodium content of lettuce.

Monitoring the birds’ behavior is easy, but proving Brightsmith’s theory that the birds are using the clay for its salt content is another story. “In math or physics, it’s easier to prove that something is true or false,” says Brightsmith. “In biology, it’s much harder.”

But math is helping answer Brightsmith’s questions. His team gathers statistical data like the number of parrots that show up at the clay wall and how long they stay. They also monitor breeding season for pairs of macaws that return to the area every year.

The data helps build a body of evidence to support Brightsmith’s clay lick hypothesis. He hasn’t yet found definitive proof for his theory. Some scientists still think the clay may play a role in removing toxins, even though parrots in jungles around the world eat toxic foods but eat clay only where the sodium levels in their diets are super-low. “It can be hard to root out a theory that’s attractive but not correct,” says Brightsmith. 

It’s not all math and tough questions for Tambopata researchers. The job also involves climbing a lot of trees. The parrot nests they study can be in tree hollows as high as 100 feet. The scientists check on the nests to determine year-to-year breeding patterns and check on the chicks.

This hands-on research has helped Brightsmith’s team discover details about every aspect of the birds’ lives as well as their habitat. The data in turn helps inform conservation efforts for macaws and other parrots in regions of the world where they are endangered. For example, the research done at Tambopata has helped parrots raised in captivity be reintroduced to the wild. 

Brightsmith looks forward to returning to Peru each year. He still has mysteries to solve and his love of the Amazon Basin grows with each passing year. “When I came here in 1993, I said I wanted to move on in five years,” he says. “I haven’t quite gotten to the moving on part yet.”