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Ecology of South American Migratory Birds at Caparú Biological Station, Bolivia

By Alex Jahn, SNRE PhD student

Although bird migration is a well-studied subject, it is often poorly understood in South America, which hosts more than 3000 bird species - more than any other continent on earth. In the 1990's, Doug Levey, a SNRE affiliate faculty member and professor in the Department of Zoology, co-authored two research papers on how bird migration to and from the Neotropics evolved. Tests of these hypotheses have primarily come from bird species that migrate to and from North American breeding grounds.

In order to develop a better understanding of how birds migrate across the New World and to provide an independent test (i.e., on a different continent) of current evolutionary theory, Alex Jahn, an SNRE doctoral student, is conducting his dissertation research under the supervision of Dr. Levey on the ecology of migratory birds that travel between Amazonian wintering grounds and south-temperate breeding grounds in South America. This type of migration has been dubbed "austral migration" and is carried out annually by over 200 birds species (mainly flycatchers, swallows and ducks), across South America.

Alex's research is focused on one species, the tropical kingbird, a widespread flycatcher that migrates throughout South America. The primary study site for this project is on the kingbird's breeding grounds at Caparú Biological Station in eastern Bolivia. There, Alex has been working with Bolivian biologists and training students from the local university, Universidad Autónoma René Gabriel Moreno, in field research techniques (e.g., capturing birds in nets). Volunteers, mainly undergraduate students from a number of universities across the U.S., have also visited Caparú to participate in the fieldwork.

Because nobody is sure when and exactly to where most bird species in South America migrate, a primary goal of the research is to understand where breeding tropical kingbirds in Bolivia migrate to spend the winter. Because many kingbirds show up in flooded forests of the central Amazon Basin during the austral winter, a second study site for this project is located along the Amazon River near the Brazilian city of Manaus.

This project is using genetic markers to determine if kingbirds indeed migrate between Bolivia and the Brazilian Amazon. Blood from captured kingbirds is collected at both the Bolivian study site during the breeding season and the Brazilian study site in the winter. The blood is then brought back to UF for analysis of DNA microsatellites at the Interdisciplinary Center for Biotechnology Research to determine if individuals that arrive at the Brazilian study site in the winter have the same genetic signature as migratory individuals that breed in Bolivia.

At Caparú, researchers are also studying the breeding biology, diet, habitat use, behavior and local movements of kingbirds to determine if these factors are useful for predicting why Kingbirds migrate. Since the Kingbird population at Caparú is likely partially migratory (i.e., some individuals migrate and others do not), the researchers have attached radio transmitters to some of the Kingbirds and have been tracking these for a period of up to six months. This will determine if the kingbirds may simply disperse locally to different habitats, instead of migrating to Brazil.

The findings of this research may have implications in many fields from conservation planning to epidemiology. In addition to testing evolutionary theory of bird migration, this research will be one of the first to provide conservation planners with a detailed model at the population level on the movements of these migratory birds in South America. This is the type of information is needed to implement effective species management plans. In addition, migration patterns can been used as an indicator of global climate change.

This research is helping epidemiologists understand the current status of the Avian Influenza virus in South America. The researchers at Caparú have formed a collaborative agreement with scientists at the University of California - Los Angeles and veterinarians in Bolivia to sample migratory birds captured in nets, as well as domestic poultry in eastern Bolivia for the virus.

Although getting to and from Caparú can be a challenge at times due to its remoteness, it is an ideal site for the study of various processes - such as bird migration - occurring at the confluence of major ecosystems. With the Amazon Basin to the north and the dry forests of central South America to the south, it is an ecotone at a grand scale within which a variety of habitats occur, with changes from one habitat (e.g., grassland) to the next (e.g., rainforest) occurring within a span of only meters.

For more information on conducting research at Caparú Biological Station, visit their website: http://www.zoo.ufl.edu/CENTERS/migration/caparu/index.html, or contact Alex Jahn (ajahn@zoo.ufl.edu) for further information on this project or for tips on research in Bolivia and Brazil.