ABSTRACT
— The small Indian mongoose (Herpestes javanicus) was introduced into the West Indies in the early 1870s and, to date, has been spread to 29 islands. Although most of these subsequent introductions occurred prior to 1900, the source of mongooses and the date of introductions can be established for at least 12 islands. The size of the founding populations, however, can be established for only five West Indian islands.
In this study, mongoose population dynamics were investigated by mark–recapture techniques on the islands of St. Croix (1983–1986; 1991–1994), Jamaica (1986), and Puerto Rico (1992–1998). Absolute identification of individual animals on St. Croix (1991–1994) and Puerto Rico (1992–1998) was made possible by surgically implanting electronic microchips. The sex ratio for populations on St. Croix and Jamaica was not significantly different from the expected 1:1; however, the Puerto Rico population was male biased probably as the result of shorter trapping episodes. Individuals from St. Croix, Jamaica, and Puerto Rico were placed in one of four age classes by tooth-wear criteria. Our early work (prior to 1991) on St. Croix and Jamaica had suggested major differences in age structure between these islands and raised some question about the validity of age determination by tooth-wear. Our more recent studies (1991–1998) using PIT tags have provided accurate information on the minimal ages of individuals, which can be compared with the age inferred from tooth-wear. Major differences were observed in the patterns of tooth-wear and hence age structure inferred from tooth-wear of populations on St. Croix and Puerto Rico. Age structure determined from minimal age of animals inferred from mark–recapture data, however, revealed no major differences in age structure between these two populations. Before tooth-wear can be used to estimate the age of individuals, each population must be examined to determine the extent of correlation between age and tooth-wear.
Population densities averaged 6.4 (range 2 to 14) animals/ha on St. Croix, 2.6 (range 1 to 7) animals/ha on Jamaica, and 4.6 (range 2 to 9) animals/ha on Puerto Rico. Comparisons of these population densities of mongoose with those reported for other islands indicate an indirect correlation between population densities and island size.
