TIL: Why Do These Birds Eat Dirt?
Did you wake up today with a craving for clay, or dirt? That’s called pica, an abnormal craving for substances other than typical food. If you went ahead and acted on your impulse, it's probably a good idea to head over to your doctor’s office. Research indicates that in most cases this craving is a result of a mineral or vitamin deficiency. This brings us to this week’s
Today I Learned, as National Geographic Society grantee and ornithologist Luke Powell explains why macaws regularly munch on South American rain forest clay. Yummy!
All animals (including humans) need salt to live. Animals that live in the Amazon rain forest face a curious predicament due to the way the Andes mountain range affects weather coming from the Pacific Ocean. This geography results in an extreme lack of salt in the Amazon and, consequentially, some unique behaviors and appetites.
EDITOR: Laurence Alexander
SERIES PRODUCER: Chris Mattle
When I'm really desperate for something salty I’ll grab maybe a pickle or bag of potato chips, but macaws, they grab a big old hunk of dirt. All animals need salt, badly, for basic biological function. Animals in the western Amazon are really deprived of salt because the Andes actually block the weather from the Pacific. So that means that all of the weather comes from the Atlantic. By the time that salty air gets all the way to the western Amazon, most of that salt has already fallen. So animals in the western Amazon are really desperate for salt, and they'll go to great lengths to get it. Macaws, in particular, which are specialized for fruit in the very highest part of the canopy will come all the way down and they'll eat the dirt. They’re selecting these very specific layers of soil that were formed over geological time during periods where conditions were a little bit saltier than in the other times. It’s like a vitamin, but it’s especially salty.
