Collared Greens

Natural History, April, 2000 by Charles Bergman

Calling with loud, raspy screeches, a pair of great green macaws flew around the huge almendro tree several times before gliding onto a high branch. Deep within a nest cavity near the top of the tree, the pair's two chicks uttered hoarse coos, begging for food. Without entering the nest, both macaw parents began a soft murmuring exchange with the expectant young. At the base of the tree, Pam Wright and Ulisis Aleman waited, as they had all morning, hoping one of the parents would enter the nest hole and thus become easier to catch. Then, if all went well, they would outfit the two-and-a-half-foot-long bird with a radio collar and transmitter. Wright is the director of and Aleman a long-time volunteer in a research project sponsored by the Tropical Science Center in Costa Rica. The information they gather may help determine the future of this macaw species in Central America.

Although Ara ambigua, the great green macaw--also known as Buffon's macaw--is a magnificent bird by any standards, until recently this species has been a stepchild of Costa Rican conservation. A model among Latin American countries for its strong environmental policies, Costa Rica is home to an impressive system of national parks and reserves. But a look at a map of protected areas reveals that the land set aside--about 24 percent of the entire country--is primarily high mountain cloud forest and secondarily the beachy Pacific coast. Virtually none of the lowland tropical rainforests of northern Costa Rica near the Caribbean coast have received protection. Characterized by evergreens and broad-leaved trees, some reaching up as high as 200 feet, this disappearing wet lowland forest is the prime habitat of the great green macaw.

The situation probably owes something to the limited resources and economic realities of the region and to the sheer numbers of species to study and protect throughout Central America. Nevertheless, it is telling that a bird so large--the second-largest parrot in the Western Hemisphere--and endangered, according to the Convention on International Trade in Endangered Species (CITES), should have been overlooked. Local people knew the great green macaw (lapa verde in Spanish), but as recently as 1993 no description of the species' primary habitat, food sources, or nesting habits had appeared in the scientific literature.

That year, George Powell visited northeastern Costa Rica, near the Nicaraguan border. Then a conservation biologist for the Philadelphia-based RARE Center for Tropical Conservation, Powell was well known in Costa Rica for his research on the resplendent quetzal and his leadership in establishing the Monteverde Cloud Forest Reserve to protect the quetzal and other species. Powell also became interested in setting conservation priorities for the lowland rainforests, and he thought the great green macaw could serve as an indicator species, a kind of barometer of the health of the ecosystem.

Conferring with residents of the region, Powell launched a study of the parrot. Ulisis Aleman, a native of El Salvador but long a resident of Costa Rica, showed Powell his first great green nest, located on a farm for the cultivation of heliconia flowers, where Aleman worked. They found three more nests that year, and Powell returned the next year to set up a team and begin full-scale research. Today, while Powell continues to guide the work, Louisiana native Pam Wright directs project operations, leading a team of volunteers: Aleman and five women from five different countries, both Central and North American.

What makes the project unusual as well as successful--and has made possible the accumulation of much of the data--is the radio-collar technique developed by Powell. Together with biologist Robin Bjork, Powell pioneered the use of radiotelemetry to discover the seasonal movement patterns of the resplendent quetzal, and he was able to adapt the device to the macaws. Only one other study, conducted in Bolivia, has used radiotelemetry to study macaws. By 1999, thirty-seven great green macaws--nineteen adults and eighteen juveniles--had been equipped with transmitters.

Radiotelemetry has proved crucial in documenting the breeding ranges, foraging habits, and seasonal movements of the great green macaw. Such natural history information is a prerequisite of any sound conservation plan. The species' habitat is limited to lowland, primarily coastal, rainforests from eastern Honduras to northern Colombia. An isolated population of fewer than two dozen individuals survives near Guayaquil, in Ecuador. According to the 1989 Guide to Birds in Costa Rica, by E Gary Stiles and Alexander E Skutch, the species once nested throughout Costa Rica's lowland forests. Through extensive fieldwork and local interviews, the macaw project has identified the major remaining breeding range of the birds in the country as an area roughly outlined by the Rio Sarapiqui on the east and the Rio San Carlos on the west; both these rivers flow into the Rio San Juan, which forms part of the country's border with Nicaragua. At about 2,600 square miles, this current range covers only 10 percent of the species' original known range (see map, page 52).