Biologist Finds That Migratory Patterns of Petén Parrots Point to Needs for Protection of Different Forest Habitats

In spite of problems caused by a growing number of human settlers who cut trees illegally and set fires that often rage out of control, the Maya Biosphere Reserve is world renowned for its tangled green menagerie of flora and fauna. Thousands of rare species find refuge in this 4-million-acre protected area in northern Guatemala. But the habits of one animal, the mealy parrot (Amazona farinosa), suggest that the reserve isn’t protecting enough different kinds of forest. Using radio telemetry, biologist Robin Bjork has been tracking these sizeable and raucous parrots for three years, and her research indicates that unless forests outside the southern border of the reserve are protected, mealy parrots — plus species that share their habitat needs — may disappear.

Illustration by Allan Núñez ('Nano')Bjork attached radio collars to a total of 21 mealy parrots that nest in Tikal National Park, where the ruins of majestic Maya temples emerge from the towering rainforest canopy. The Maya Biosphere Reserve, Tikal, and several other protected areas are all located in the area called the Petén, which juts into the Yucatán peninsula of Mexico and is flanked on the east by Belize. Bjork and her assistants are able to track the 15-inch parrots’ movements on foot and by small airplane, holding aloft antennas that pick up the signals emitted by the collars.

Most parrots range widely through forests, but Bjork was unprepared for the treks her tagged parrots take. They leave their nesting grounds in June and first embark on a 25- to 50-mile jaunt north for a few weeks, then reverse course and soar some 125 miles to southwest Petén, sometimes as far as Chiapas, Mexico. In December and January, they make their way home — returning to their exact nesting spots, which are in holes in tall tropical trees. Most parrots nest in mature forests, because the cavities they need are found only in older trees, whose wood is beginning to rot away. Parrots often enlarge the holes with their beaks.

Mealy parrots are bright green, with muted blue feathers tingeing the tops of their heads and backs of their necks. Each wing bears a slash of scarlet, and the tips of their tails are pale yellow. But their prevailing green plumage helps explain why little is known about their habits — since they generally stick to the treetops, they are nearly impossible for the human eye, fifty feet below, to spot amidst dense foliage. Bjork says hers is one of just a few telemetry studies of larger parrots and notes she was lucky to have access to safe, small airplanes, plus the funding to pay for aerial tracking. Her research, done for her Ph.D. dissertation at Oregon State University, has received support from Wildlife Conservation Society and the US Environmental Protection Agency, with additional support from American Bird Conservancy and the World Wildlife Fund.

Found from southern Mexico to western Ecuador, Bolivia and southeastern Brazil, mealy parrots are fairly abundant in humid, heavily forested areas. Like many other parrots in the Amazona genus, their fledglings are often stolen from their nests for the pet trade, but deforestation is their main threat. Since the Petén forests where the parrots spend some five months of the year are not protected and increasingly logged, the birds face an uncertain future.

Bjork says that on maps, all the forests of the Petén are usually classified the same way: as upland, tropical forests. So in designating the Maya Biosphere Reserve and other parklands in the region, the Guatemala government and advising scientists likely assumed that they were protecting a relatively large swath of upland forest. But Bjork’s study reveals that forests that seem similar to human beings are crucially different to mealy parrots.

“The mealy parrots show us that specific to the Petén, there are differences in vegetation that we need to consider in regional, protected-areas planning,” the biologist explains. “The birds are signaling where there are different habitat types, though they may look enough the same to us.”

She suspects that the mealy parrots’ migration patterns are food-related, although she is just beginning the research that will confirm that hypothesis. Her preliminary information indicates that when the birds leave an area, the abundance of fruit has gone way down. The parrots primarily eat fruits of mature-forest trees and seem particularly fond of fruits of a hardwood species commonly known as ramón (Brosimum alicastrum), which is becoming an increasingly popular commercial timber species.

After three years chasing after the rainforest birds, Bjork wants to use her findings to identify biologically unique habitats and provide scientific ammunition for protection of biodiversity in lowland tropical systems. Carlos Albacete, with the nonprofit group Trópico Verde-Parks Watch Guatemala, is familiar with the study and believes it helps prove that in protected-areas conservation, “not just size is important, but also location, climate factors, and forest dynamics must be determinants.” He believes the research can be a valuable technical tool that can advance decision-making. “Up to now, decisions about what land to protect have been made according to political and social points-of-view, rather than scientific,” he notes.

Bjork has presented her findings to a coalition of international conservation groups that are involved in designing management plans for the Maya Biosphere Reserve, plus a German nonprofit group called PROSELVA, which until funding shortages ended their work, directed sustainable development initiatives in southwestern Petén, where more slash-and-burn farmers arrive each month. She has talked to the US Agency for International Development, which devotes millions of dollars to conservation in the reserve, and perhaps most importantly, she has earned the attention of Guatemala’s Council for National Protected Areas. The government has granted logging concessions to several small communities inside the Maya Biosphere Reserve, including one in a forest that is the first stop for the parrots after they leave their nesting grounds. Bjork has presented her maps and her data to try to influence forest management and future protected-areas design.

Not every biologist in search of a Ph.D. adds such lobbying to her dissertation work, but Bjork thinks it’s her obligation. “There’s a big push for development in Guatemala, with oil exploration and road building,” she says. “If we biologists don’t find ways to directly apply our research to conservation, we will lose the chance to identify sites that are critical to maintenance of biodiversity before they’re gone.”

She hopes to pursue answers to other questions she believes are important to the management of the Petén and other large park systems. For example, she wants to learn more about what drives her tagged Tikal parrots to migrate and find out if mealy parrots that nest in other areas of the Petén also migrate. She also wonders if other members of the Psittacidae family, such as scarlet macaws, share the need for habitat gradients that seem markedly subtle to humans – the species that controls the way land is used — but are vital to other species’ survival.

Contacts:

Robin Bjork
Dept. of Fisheries and Wildlife
Oregon State University
Corvallis, Oregon 97339 USA
Tel: 208/331-1038
Email: rdbjork@hotmail.com

Trópico Verde
Tel-Fax: 502/634-1444
Email: mailto@tropicoverde.org

Read more about this research in the Eco-Index.

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