5. Parrot Salt Licks

Why do Amazonian Parrots eat dirt? Here I explain in National Geographic's web series Today I learned:

More on Salt licks or "collpas:

"Collpa", pronounced "KOWL-pah" is the Quechua word for salt lick. Collpas are soil horizons—usually found on river banks—that are regularly eaten by Amazonian animals. I am interested in what specifically it is about collpas that makes them attractive to parrots, and whether use of collpas correlates with animal fitness. An article published in the journal Biotropica by myself and colleagues shows that the soil layers targeted by parrots are higher in sodium than soil layers that parrots don't use (download supplementary tables or supplementary figure).

There I am collecting soil at a collpa on the Rio Piedras in Southeastern Peru.

Soil collection technique was highly sophisticated: I slammed a screwdriver into the rock-hard soil until pieces fell off - then I scooped them up with a Ziplock bag.

One missing piece of the puzzle is that the only known study on parrots' ability to detect salt suggests that Australian Budgerigar parrots cannot taste sodium at such low concentrations. To determine if new world parrots can detect sodium levels similar to those found in collpas, myself and colleagues Dr. Thomas Tully and Kelsy Jones are performing taste test experiments on twenty captive Hispaniolan Amazon parrots at LSU. We hope that this work will eventually help us understand the conservation value of this resource.

Red-and-green Macaws eating from a Collpa in Madre de Dios, Peru.

The macaws gradually dug those holes in the bank as they ate the soil.

Occasionally dozens of them would get scared and flush, and one or two would get stuck inside the holes - probably wondering what the heck happened!