The impact of free-roaming dogs on gazelle kid/female ratio in a fragmented area

摘要

One of the consequences of fragmentation is a combination of increased proximity to human dominated areas and an influx of free-roaming dogs. In fragmented habitats those dogs are expected to have a considerable impact on ungulate populations since conditions are, in effect, similar to alien species on islands. We studied the impact of free-roaming dogs (Call is familiaris) on the kid/mother ratio of mountain gazelle (Gazella gazella gazella) in an isolated area heavily disturbed by human activity. We used the kid/female ratio as an index of recruitment in the gazelle populations and evaluated the impacts of dog presence, intensity of human disturbance, and forage and cover availability on this ratio over space and time. Data were collected from direct observations. Overall, kid/female ratio in the area is too low for population growth; a finding that is in agreement with drive counts indicating a consistent decline over the past four years (1998-2001). Our results show that free-roaming dogs were the overwhelming factor affecting kid/female ratio in this area. Gazelles responded positively and quickly to dog culling. Thus, free-roaming dogs appear to be a considerable threat to the gazelle population in the study area. Removal of those dogs on a regular basis is an adequate short-term management protocol for increasing gazelle recruitment rate. However, a permanent solution would require reducing the number of dogs by limiting human waste disposal. These results suggest that, in addition to the loss of habitat and connectivity, free-roaming dogs can be a major threat to native ungulates in human dominated fragmented landscapes.