Why are Hundreds of Parrots Congregating on Cliffs in South America to Eat Clay?

In Peru, South America, there is a phenomenon taking place with local avian populations. There, large numbers of Macaws, Amazon Parrots, Parakeets, and other birds congregate every day in order to consume the clay on cliffs in the rainforest. These areas that contain the clay are known as “clay licks.”  Locally, these areas are known as “Ccollpa.” These cliffs are located on steep walls and contain clay as a result of erosion along rivers in the Amazon basin, and are associated with moist forests on younger geological formations and exposed river banks.

The Mystery of Parrot Geophagy

For some time, researchers and observers were baffled as to why parrots would flock in such large numbers to these cliffs to eat the soil. Though there were differing theories surrounding this spectacle, it was widely considered a very mysterious behavior even among experts. As theories started to circulate, so did the motivation to figure out this mystery. The practice of eating soil is called Geophagy. Researchers have started to observe and study this phenomenon and have gathered some interesting data about the birds and their behavior.

One of the largest clay licks is the Chuncho clay lick. It is located in the heart of the Tambopata National Reserve. This reserve has been defended by researchers and others because it is one of the last remaining pristine areas of rainforest in South America. It is also one of the few remaining areas with lowland and foothill rainforests that also connect to more forest in higher elevations and wet savannahs.

These clay licks contain soil that is rich in minerals and sodium. Sodium specifically has always been thought to be a large driver for geophagy in parrots. Past studies have shown that the western Amazon Basin is “chronically sodium-deprived” which means it can be hard to come by for the parrots that call that place home. Though the exact reasoning for why a parrot would want to consume the clay has been a topic of debate, many believe the clay contains the minerals and sodium that a parrot’s diet may lack from a plant-based diet alone. These could provide important supplementation in their diet. Some researchers have also hypothesized that the clay from these cliffs may also help protect parrots from toxins from certain food sources when food supply is limited.

Parrots of different species, though mainly Macaws, congregate at specific times of the day to consume the clay. Hundreds can be seen at a time doing so. When scientists started looking closely at this phenomenon, they noted that the frequency of the behavior seemed to vary depending on the season, with overall species-wide clay lick use peaking during the breeding season. This gave scientists an important clue and direction in their studies.

Testing the Theories 

There are two main hypotheses, or theories, for why parrots consume the clay. These theories were recently tested by the Tambopata Macaw Project. This project was done by many scientists, researchers and over 500 volunteers and has provided some great insight into this phenomenon. It was conducted in the western amazon basin. Let's take a look at the study that was conducted and what they found.   

The first hypothesis that was tested is the “toxin-protection hypothesis.” This hypothesis theorizes that the reason for the clay consumption is to help parrots deal with toxins that are contained in plants during certain seasons. For example, if food resources are low or limited, birds may be forced to eat certain plants that contain these toxins when they normally would not or would eat much less of them. To test the first theory, scientists studied food availability datasets. This theory predicts that high clay lick use will occur when food availability is low or restricted. They analyzed clay lick activity across multiple species and also studied each species behavior separately. By observing clay lick activity and comparing it to food availability, they were able to document if there was a correlation. If there was a significant negative correlation between the two, then the toxin protection hypothesis would be supported. 

After conducting their research, the scientists actually found no evidence that clay lick use was high during times of low food availability. Instead, they actually found a positive correlation between the pooled species data and food availability. Even looking at the data for each individual species of parrot, there was no significant negative correlation between clay lick use and overall food availability.

The second hypothesis that was tested was the “supplemental nutrient hypothesis.” This one theorizes that clay lick use occurs as a way for the birds to supplement nutrients that they may need more of during breeding season and other important times. Instead of the birds reacting to low food availability, this would instead be a reaction to what the birds need based on what they might be missing nutritionally. 

In order to test this theory, scientists examined the patterns of each species’ clay lick use with their breeding data. Using available data, it was found that peak clay lick use occurred during the breeding season, and that trend held regardless of the season in which the parrots bred. It was determined that clay lick use patterns significantly overlapped with the breeding seasons for each parrot. Another interesting fact is that all species at the research site from which scientists collected crop samples were known to feed the clay to their chicks.

Whole nutrition is extremely important to the wellbeing of a bird, and that’s why Bird Street Bistro wants to help parrot owners bridge the nutritional gap in their homes by offering healthy, safe food options for their birds. They realize it can be a challenge sometimes to make sure our birds have the nutrition they need since most of us probably don’t have a clay lick readily available!

Conclusions From the Study

As a result of the study, scientists feel that there is more evidence that the use of clay licks is to provide supplemental nutrients and not to help protect against toxins. However, it is important to keep in mind that these two theories are not mutually exclusive, and that it is possible that they can overlap and both drive the birds to consume the clay.

The Tambopata Clay Licks and Ecotourism 

Tours are offered in many locations, including Tambopata National Reserve, to help fund research like this on parrots including the nutritional challenges that they face due to climate change and other factors threatening their livelihood. These tours take people to witness the birds on the cliffs and often include a place to sleep, eat and learn more about the parrots. This funding is important and very beneficial to help continue research and rescue efforts for many species that are experiencing hardship. Most of the issues that parrots face in the rainforest are due to human activities. Funding can be hard to come by and so these eco tourism practices help provide that funding while also educating the public about their efforts and the important impact people have had on the rainforest.

Regardless of why the parrots choose to congregate as they do and partake of the clay, it is a magnificent sight to behold. Their drive to not only survive, but also thrive despite adversity, can teach us a lot about how we can also do the same. By further investigating what drives these birds to behave the way that they do, we can help ensure that they have a longer, healthier future alongside us on the planet. By also continuing to offer tours and educate others we can also help to fix some of the damage we have done to their habitat along the way.