Texas A&M Professor Explores Why Peruvian Parrots Eat Clay
Posted July 26, 2017
Dr. Donald Brightsmith
For more than 16 years, researchers and volunteers have been
observing wildlife along the clay cliffs of Southeastern Peru’s
Tambopata River. They’ve gathered data every day, logging more than
20,000 hours and building one of the most extensive datasets on
tropical parrots in the world.
In a new paper published in Ibis, Elizabeth Hobson, a
postdoctoral fellow with the Arizona State University-Santa Fe
Institute Center for Biosocial Complex Systems, and Donald J.
Brightsmith, a professor in the Texas A&M University College of
Veterinary Medicine & Biomedical Sciences (CVM) and director of
the Tambopata Macaw Project, begin to analyze the data from this
In particular, the two explore the potential
drivers behind geophagy—or intentional soil consumption—they’ve
regularly observed in 14 different parrot species there.
This region of the Tambopata River in Southeast
Peru is an ideal spot to study the nearly two-dozen parrot species
that live nearby in the Amazon rainforest. In the thick foliage of
the jungle, the birds are difficult to see, but when they emerge to
gather up beakfuls of the sodium-rich clay soil, “it’s a crazy,
screaming kaleidoscope of color,” Hobson said.
“They’re all quiet when they take flight, but in a
few seconds, they all begin to scream, and some drop bits of the
clay from their mouths,” said Brightsmith, who has led the
Tambopata Macaw Project since 1999. “It’s an incredible
But geophagy is a somewhat confounding
behavior—clay soil is basically inert.
“It doesn’t have proteins, carbohydrates, or
really anything that you’d need,” Brightsmith said. “If we can
understand why it’s so important to these parrots, we can learn
more about the ecosystem and how it affects the other insects,
birds, and mammals who also eat this soil.”
Geophagy occurs around the world and in many types
of animals, and scientists have proposed many explanations for the
behavior. In their paper, Hobson and Brightsmith explore the two
leading theories for these Amazonian parrots—that clay soils help
protect the birds from food toxins when ideal food sources are
scarce and that clay soils provide necessary minerals not available
in the parrots’ regular diet.
Like previous studies, their analysis suggests
that toxin-protection is not a driver. But parrot geophagy there is
highly correlated with breeding season, suggesting the increased
nutritional demands are likely behind the soil consumption. This
study also joins a large body of research suggesting that hunger
for sodium, specifically, is that driver.
“There’s lots of evidence that’s pointing in that
direction,” Hobson said. “Sodium in the rainforest is really rare,
and the place on these clay licks most preferred by the birds also
has the highest sodium content.”
Understanding how nutritional needs are—and are
not—being met during breeding season becomes even more important in
light of climate change, according to Brightsmith. Some of the
larger macaws are already breeding right before a seasonal crash in
food supply, requiring parents take their fledgling young on long
flights to find food.
“If climate change starts messing with the macaw’s
food supply, it could disrupt their ability to breed,” he said.
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