Bette A. Loiselle, Ph.D., University of Wisconsin

Email: loiselle@jinx.umsl.edu

Education

Selected Publications

 

Research Interests

My research interests, in a broad sense, are in the evolution and ecology of seed dispersal systems in the tropics and the conservation of tropical vertebrates, especially birds. Below I summarize recently completed research and research in progress.

Population dynamics and conservation of frugivorous birds.

Together with John G. Blake, I initiated a long-term study of frugivorous birds and their food plants in La Selva-Braulio Carrillo extension during January 1985. Located in northeast Costa Rica, this protected transect goes from tropical wet forest near sea level at the Organization for Tropical Studies' La Selva Biological Station (36 m) to montane rainforests in Braulio Carrillo National Park (highest point at 2906 m, Barva Volcano). We have sampled the abundances and habitat use of birds using mist nets and point-count censuses in several habitats at La Selva (1985-present; 10 continuous years) and from 3-5 forest elevations within the National Park. Our results documented altitudinal migrations by frugivorous birds and tied these migrations to changes in fruit resource availability along the gradient. Although there can be considerable annual variation in the extent and duration of altitudinal movements by frugivorous species (and by sexes within species), there also is a great deal of predictability in these movements. Within lowland forest at La Selva (i.e., at a smaller spatial scale), we also have demonstrated through correlative analyses that the spatial habitat use by birds is predicted by the availability of plants with ripe fruits in the understory. In remnant tropical forest areas, the extent to which tropical populations vary takes on increasing importance for their conservation. In small reserves, conservation and population biology theory predict that the more variable populations are, the greater probability that those populations will go extinct through stochastic processes. Our long-term studies of birds evaluate population variation in this forest. We have found birds that rarely used disturbed forest patches showed the greatest degree of population variation. This result is particularly worrisome for the long-term conservation of these forest-restricted species at La Selva given that this lowland forest is surrounded on three sides by agricultural or pasture land, including a recent large-scale banana plantation on the east side.

Differential role of avian seed dispersers and ecological consequences for tropical plants.

The extent to which birds influence the evolutionary dynamics of plant populations will depend on the temporal predictability of fruit choice and habitat use by birds and the role that chance plays in seed and seedling establishment following dissemination of seeds. Our (with John G. Blake) results suggest that fruit-handling techniques and general habitat use patterns of birds are temporally predictable and understory birds differ in their effectiveness as seed dispersers for individual plant species. Currently, we (with Victoria Sork) preliminarily tested the genetic consequences of seed dispersal by birds for Psychotria officinalis, an understory shrub in the Rubiaceae (see Loiselle, Sork et al. 1995). Presently, experiments are being designed to investigate the relative impact of seed dispersers, pollinators, and natural selection on the spatial dispersion of individuals within mature forest at La Selva. Our long-term goals for this study will be to dissect out the individual roles of avian dispersers and model the impact to plant populations when local seed dispersers go extinct.

GIS and bird conservation.

Together with Jaqueline Goerck and Milton Ribeiro, we are using museum records of birds in the bird families, Cotingidae and Pipridae, and GIS environmental layers digitized from the National Atlas of Brazil, to model historic distributions of birds in the Atlantic Forest of Brazil. These distributions are then compared to present day extent of forest to estimate the amount of the original range lost and its spatial biases (i.e., presence/absence of peripheral and central populations). This GIS work is the first step in a long-term, collaborative research plan to investigate the population ecology and conservation of birds in the region. National Geographic Society has supported the field portion of the project.

Plant-bird studies in Colombia.

Together with Colombian colleagues, Gustavo Kattan and Carolina Murcia, and post-doctoral associate, Ana Cristina Villegas, I am initiating a project that examines the factors affecting maternal fitness for three species of Palicourea (Rubiaceae) in the central Andes of Colombia. These species grow in the understory of tree plantations and old-growth forest. Our goals are to determine which processes best explain maternal fitness, which is measured at several different stages, and how these processes might change in importance across closely related sympatric species and sites. Ultimately, we hope to use these studies to understand what factors might limit plant distributions, and identify key processes related to regeneration in abandoned tree plantations.

 

Recent Graduate Students

Present Graduate Students

Courses and Seminars

Theory and Applications of Conservation Biology

Ecology and Conservation of Fragmented Forests in the Tropics