Macaw and Clay Lick Studies at Tambopata Research Center, Peru


In late 1989 a group of researchers including two young Peruvians Eduardo Nycander and Kurt Holle traveled up the Tambopata River in southeastern Peru and established the Tambopata Research Center. Their goal was to study and preserve the large macaws that were so incredibly abundant at the site. They chose this area because it is immediately adjacent to a 100 foot tall river edge cliff or "clay lick" were up to I 000 parrots and macaws gather daily to eat clays rich in sodium. Under Eduardo's leadership the researchers constructed the first nest boxes ever used by wild macaws, saved and released doomed macaw chicks, and carried on intensive studies of reproductive ecology of Scarlet, Green-winged and Blue-and-Gold Macaws (for more information see Nycander et al 1995). This work continued in earnest until 1993 when the funding for the research dried up and Eduardo and Kurt had to make a difficult decision: give up and go back to Lima or try to find a way to maintain the station and continue their work with the birds. Their decision was to use ecotourism to fund the station and with that they founded Rainforest Expeditions.

ln the years since 1993 they discovered that building a successful ecotourism operation was more than a full time job. As a result the pace of the research slowed as the company became established in the international marketplace. By 1999 Rainforest Expeditions had opened a second lodge, Posada Amazonas, won a number of international awards, and become a leader in Peruvian ecotourism. At this point the company was ready to reinvest in the macaw and parrot research that had given birth to the entire operation. In November l 999 they hired me, Dr. Don Brightsmith a research associate at Duke University, to take over the macaw research.

Since 1999 I have been using Tambopata Research Center as a base for my studies of many aspects macaw and parrot natural history and management. Some of the topics under study include: Blue-and-gold Macaw nesting and habitat management, macaw and parrot diets, nest box use by large macaws, Scarlet Macaw chick growth and survival, seasonal fluctuations in macaw and parrot abundances, the role of nest temperature and humidity in Scarlet Macaw hatching success, nest attendance patterns of Scarlet Macaws, and supplemental feeding as a method to increase macaw productivity. I have also begun intensive studies on the clay lick adjacent to the research center. For the remainder of this article I would like to review why birds use licks and briefly discuss some of the new information that I have discovered during my work in Tambopata.

Throughout the western Amazon Basin in the nations of Ecuador, Peru, and Bolivia parrots, pigeons and turkeylike birds called guans assemble daily along the banks of streams and rivers to eat clay. The birds are apparently very selective as they habitually come to certain small sections of cliff while leaving other nearby sections almost completely untouched. In their landmark work on clay licks James Gilardi and colleagues (Gilardi, et. al 1999) showed that the clays from these licks effectively reduce the damaging effects of the toxic chemicals found in the seeds that the birds eat. Work I have conducted along the lower Tarnbopata River shows that birds eat significantly more clay from riverbanks with higher concentrations of sodium. As a result it seems that both detoxification and sodium are driving parrots to eat clay.

Since February of 2000 my research team have collected data at the clay lick on over 900 days. Over 600 days worth of data have been entered in to the computer and arc currently being analyzed. This data set has proven incredibly valuable for documenting how the use of the lick is affected by the weather and how it changes with the seasons. One of the most obvious things is that macaw and parrot use of the lick is greatly reduced by rain. In fact during most rainy mornings there are almost no birds that go to the lick. Another obvious pattern is that many birds almost only use the lick in the early morning. For example Mealy Amazon, Severe Macaw, Red-bellied Macaw, Yellowcrowned Amazon, Blue-headed Pionus, and others use the lick almost exclusively between sunrise and about 7:30 A.M. Interestingly enough, if it rains in the early morning these species will not go to the lick later in the day even if it is warm and sunny. Why the birds don't make up for these lost opportunities is unknown. Looking at the data between days I also found that the birds don't make up for "lost opportunities." Earlier research had suggested that macaws went to the lick once every 2 - 3 days (Munn 1992). For this reason I expected that after a series of rainy days I would find nearly twice as many birds on the lick. But upon analysis of my data it became clear that extra birds did not come to nor did birds spend an extra long time on the lick to make up for the mornings lost to the rainy weather.

The question now is how can we interpret these new findings in light of what we know about why birds eat clay? If the clay protects the birds from dietary toxins they should need to eat clay daily, preferably before going out and feeding. As a result, it makes sense that they do not eat extra clay after missing a day. But in this case what happens on days when they can't get clay? Do they have to switch to food sources with lower toxicity and what effect would this have? Also why don't the birds go to the lick later in the day once the rain stops? If the birds are eating soil to get sodium, why don't they eat extra clay to make up for amount of sodium they missed the day before? These questions are difficult ones to answer, but I plan to use them to mold my future research efforts and work to increase our knowledge of clay licks and the role they play in parrot...