PUERTO-RICAN PARROTS AND POTENTIAL LIMITATIONS OF THE METAPOPULATION APPROACH TO SPECIES CONSERVATION

Population viability analyses for a number of endangered species have incorporated a metapopulation approach. The risk assessments of these viability analyses have indicated that some extant populations should be subdivided into numerous subgroups with exchange of individuals amo ng them in order to reduce the chance of catastrophic loss of the spec ies However, routine application of a policy of extensive subdivision may have detrimental consequences for certain endangered species. We e xamine the Puerto Rican Parrot as a case history in which this policy is ill-advised. In 1989, a population viability analysis was conducted for the parrot. The document recommended subdivision of the existing small captive flock into three groups. One of these captive flocks wou ld consist of individuals transferred to a multi-species facility in t he continental United States Subsequently, individuals from this facil ity would be exchanged with the insular captive population(s) and the relict wild flock For two reasons, implementation of this recommendati on might have led to serious repercussions. First, this parrot, like m any endangered species, has gone through a genetic bottleneck and may have a heightened susceptibility to disease- Multi-species facilities are a high-risk environment favoring the transmission of pathogens, es pecially when the facilities are located outside the natural ranges of a particular species. Second, the parrot is a K-selected species for which mate selection is idiosyncratic. This type of species often prov es difficult to breed in captivity in small groups. Part of the proble m in mate selection may be reduced by a Policy allowing frequent trans fers of individuals among facilities, but such movements increase the chances of spreading disease in the metapopulation Thus, population vi ability analyses need to acknowledge that proliferation of captive sub groups accompanied by exchanges of individuals can in themselves carry substantial risks that must be weighed against the presumed benefits of subdivision.