The Parrots Which Feed on Dirt
If you are fortunate enough to visit Peru, there are many spectacular sights to take in. You will be sure to head for Machu Picchu and you might also wish to visit Lake Titicaca. But if you love birds, you should head for the clay cliffs alongside the Tambopata River.
The clay cliffs are also known as the clay licks because 18 species of tropical birds visit them to practice geophagy, the eating of soil. The cliffs create one of nature’s most dramatic and colourful spectacles when the parrots congregate to feed. Scarlet macaws, blue-and-yellow macaws and Southern mealy parrots are amongst the regular visitors to the cliffs.
But what makes this particular dirt such an attraction for the birds?
In Search of Sodium
Until recently, scientists weren’t entirely sure why the birds eat the dirt but had proposed two possible reasons. Either the birds were seeking out rare nutrients or they were attempting to neutralise plant toxins.
Research has produced little evidence that the birds are eating dirt to purge toxins. It seems more likely that it is a shortage of nutrients which is driving the parrots to the cliffs. Scientists have noted that the regions where such feeing behaviours are observed tend to be at some distance from the ocean and to feature plants which are low in sodium.
It is rare to find a source of sodium in rainforests but the cliffs have high levels of sodium. This is an essential nutrient which supports nerve function and muscle contraction. The clay licks in the Amazon Basin boast sodium concentrations which are 40 times greater than those in the plants eaten by the parrots.
It is possible that the clay cliffs are so rich in sodium because it was laid down by ancient inland seas but this has yet to be proven.
Parrot feeding Patterns
Researchers have been studying the feeding pattern of the parrots in order to determine why they eat the soil. They have established that geophagy peaks in the breeding season when parrots are most likely to need supplemental nutrition. This is further evidence that the parrots are seeking out sodium and not a purge for toxins. If the latter was the case, feeding at the cliffs would peak at times when the availability of plant based foods is low as this would force the parrots to eat a higher volume of toxic material.
Parrots Lack Animal Protein in their Diets
Other birds including pigeons and guans also visit the clay licks. Like parrots, these species have a diet which does not feature the insect and animal protein which would provide a source of sodium. However, the hypothesis that the parrots need sodium does not preclude the clay’s usefulness as a binder for toxins. Perhaps the parrots benefit from both properties of the clay.
Parrots and Climate Change
Scientists are concerned that climate change could seriously impact the feeding patterns of the parrots. Their chicks fledge just at the time when food sources are becoming scarce, forcing them to travel far and wide in search of meal. Global warming could cause plant growth to peak earlier and the result would be adult birds which are in even greater need of nutrients.