Density and Home Range of Cats in a Small Inhabited Mediterranean Island

Simple Summary Domestic cats have spread worldwide, and their populations on islands have a significant impact on biodiversity. Particularly on small inhabited islands of tourist importance, cats can reach high densities. To evaluate cat impacts and plan cat population management, it is essential to know their population size and spatial distribution. This study examines the cat population on the small island of Tabarca (40 ha), near the Spanish Mediterranean coast, which includes a small village. Tabarca is included in the Natura 2000 Network due to its environmental value and bird populations. The overall cat density is among the highest reported (308 cats/km2), varying between the urban area (1084 cats/km2) and the uninhabited scrubland area (27 cats/km2). The home ranges of urban cats are much smaller (average 0.38 ha or 1.25 ha, depending on the estimation method) than those of cats in the scrubland (average 9.53 ha). These findings indicate that the urban area is a source of cats that colonize the scrubland. Despite the majority of cats being sterilized by the study's end (89.5% of males and 91.7% of females), the population decline will be slow, taking many years to reach acceptable levels. Therefore, additional management measures are recommended to mitigate the cat population's impact on biodiversity.Abstract There is growing concern about effectively controlling cat populations due to their impact on biodiversity, especially on islands. To plan this management, it is essential to know the cat population size, sterilization rates, and space they use. Small inhabited islands can have very high cat densities; thus, this study aimed to evaluate cat density and home range on a small tourist island in the Spanish Mediterranean. Surveys in the urban area identified individual cats using a photographic catalog, and camera trapping was conducted in the scrubland area. GPS devices were fitted on three urban cats. The overall cat density was estimated to be 308 cats/km2, varying between the urban area (1084 cats/km2) and the uninhabited scrubland (27 cats/km2). Urban cats had smaller average home ranges (0.38 ha or 1.25 ha, depending on the estimation method) compared to scrubland cats (9.53 ha). Penetration of scrubland cats into the urban area was not detected. These results indicate that the urban area acts as a source of cats for the scrubland. Although the total sterilization rate was high (90.3%), the large cat population implies that the density would take over a decade to decrease to acceptable levels. Therefore, complementary measures for managing this cat population are recommended.