Human activities associated with reduced Komodo dragon habitat use and range loss on Flores

Abstract

Species restricted to archipelagos are often range-restricted, dispersal limited, and persist as disjunct populations. These attributes can make island populations especially vulnerable to extinction from natural or anthropogenic processes. Ascertaining causes of habitat use, population impact, and range loss is fundamental to guiding effective conservation actions. The Komodo dragon (Varanus komodoensis) is an endangered, island-endemic species with a highly restricted range distribution limited to a small number of islands in Eastern Indonesia. Flores Island is the largest island (13,540 km2) within the species distribution. However, with relatively few and small-protected areas, alongside a much higher incidence of human-related habitat use, Komodo dragon habitat occupancy is suspected to decrease on Flores. Here over five years, we conducted systematic surveys to evaluate Komodo dragon habitat occupancy at 346 camera monitoring stations (CMS) distributed along the Flores coastline. We successfully detected Komodo dragons at 85 of the 346 CMS on Flores. The pattern of Komodo dragon site presence indicated their distribution was confined to three isolated and highly restricted habitat areas on the west, northwestern, and northern coastal regions of Flores. Ranking of competing models indicated that proximity to farms and villages had the strongest negative effects on Komodo dragon habitat occupancy. The current predicted Komodo dragon range distribution appeared to have undergone significant range area contraction (~ 44%) at multiple coastal areas known to be occupied by the Komodo dragon detected in previous decades (i.e., 1970–2000). We attribute decreased Komodo dragon habitat use and range loss to multiple and cascading human activities. To address these threats, we advocate a range of land use planning and community conservation actions to avoid a potential Komodo dragon extirpation on the largest island habitat within their distribution.