Puerto Rican vireo demography in a montane habitat, with metapopulation implications

From 1998–2000 I studied the biology of an insular endemic, the Puerto Rican Vireo (PRVI; Vireo latimeri) in Maricao State Forest, a montane forest in western Puerto Rico, to assess the effects of demographic parameters on the stability of the population. None of the PRVI nests was parasitized, but 65% of 40 active nests were depredated. Overall daily nest survival was 0.932. Fifty-two percent of the pairs were successful in a breeding season. The annual production of young was 1.21 fledglings per pair. Adult annual survival was lower from 1998–1999 (39%) than from 1999–2000 (72.2%) possibly due to the passage of Hurricane Georges in 1998.; A Lefkovich stage-based matrix with a metapopulation structure was used to model the source-sink dynamics believed to occur between montane and coastal populations of the PRVI. Results found in Maricao indicates a potential for being a source (λ > 1), whereas results found in the literature from a study conducted in Guánica State Forest suggests this coastal population is a sink (λ < 1), due to high brood parasitism and nest predation. High reproductive success in Maricao accounted for a growing population (λ = 1.14). The population growth rate in Guánica changed from <1 (λ = 0.85) when isolated to >1 (λ = 1.05) when it received migration. To prevent the sink's extinction, juvenile migration rate from the source to the sink should be of at least 16%.; I assessed the characteristics of forest fragments (i.e., area, perimeter, elevation above sea level, isolation) in the landscape surrounding the breeding grounds of the PRVI in Maricao to relate them to the species presence or absence. Aerial photographs were classified according to 10 land-use categories and digitized into a geographic information system. Fifty percent of the patches (7/14) were occupied by single males or one pair, but none of the patch characteristics predicted the presence of the vireos. The low population density in the patches suggests they provide low quality habitat compared to the large expanse of continuous forest in the landscape where the vireos have higher pairing and breeding success.