Spatial variation in leopard (Panthera pardus) site use across a gradient of anthropogenic pressure in Tanzania's Ruaha landscape

Abstract

Understanding large carnivore occurrence patterns in anthropogenic landscapes adjacent to protected areas is central to developing actions for species conservation in an increasingly human-dominated world. Among large carnivores, leopards (Panthera pardus) are the most widely distributed felid. Leopards occupying anthropogenic landscapes frequently come into conflict with humans, which often results in leopard mortality. Leopards' use of anthropogenic landscapes, and their frequent involvement with conflict, make them an insightful species for understanding the determinants of carnivore occurrence across human-dominated habitats. We evaluated the spatial variation in leopard site use across a multiple-use landscape in Tanzania's Ruaha landscape. Our study region encompassed i) Ruaha National Park, where human activities were restricted and sport hunting was prohibited; ii) the Pawaga-Idodi Wildlife Management Area, where wildlife sport hunting, wildlife poaching, and illegal pastoralism all occurred at relatively low levels; and iii) surrounding village lands where carnivores and other wildlife were frequently exposed to human-carnivore conflict related-killings and agricultural habitat conversion and development. We investigated leopard occurrence across the study region via an extensive camera trapping network. We estimated site use as a function of environmental (i.e. habitat and anthropogenic) variables using occupancy models within a Bayesian framework. We observed a steady decline in leopard site use with downgrading protected area status from the national park to the Wildlife Management Area and village lands. Our findings suggest that human-related activities such as increased livestock presence and proximity to human households exerted stronger influence than prey availability on leopard site use, and were the major limiting factors of leopard distribution across the gradient of human pressure, especially in the village lands outside Ruaha National Park. Overall, our study provides valuable information about the determinants of spatial distribution of leopards in human-dominated landscapes that can help inform conservation strategies in the borderlands adjacent to protected areas.

Fig 1. Spatial distribution of the camera-trap stations (red shaded circles) across the Ruaha landscape.

1–11 represents sampling areas: 1. Mdonya; 2. Kwihala; 3. Msembe; 4. Mwagusi; 5. Lunda-Ilolo; 6. Pawaga; 7. Lunda; 8. Idodi; 9. Malinzanga; 10. Nyamahana; 11. Magosi. The yellow shaded circles represent the number of independent detections of leopards (Panthera pardus) at each camera-trap station (> 5 minutes between detection).

Fig 2. Independent detections of the main leopard prey species at each camera-trap station.

A. Bushbuck (Tragelaphus scriptus); B. Common duiker (Sylvicapra grimmia); C. Greater kudu (Tragelaphus strepsiceros); D. Impala (Aepyceros melampus); E. Warthog (Phacochoerus africanus); F. Livestock. 1–11 represents sampling areas: 1. Mdonya; 2. Kwihala; 3. Msembe; 4. Mwagusi; 5. Lunda-Ilolo; 6. Pawaga; 7. Lunda; 8. Idodi; 9. Malinzanga; 10. Nyamahana; 11. Magosi.

Fig 3. Variation in prey detection across the gradient of anthropogenic pressure in the Ruaha landscape.

Independent events (> 5 min interval between detection). Bushbuck (Tragelaphus scriptus); Common duiker (Sylvicapra grimmia); Greater kudu (Tragelaphus strepsiceros); Impala (Aepyceros melampus); Warthog (Phacochoerus africanus).

Fig 4. Predicted association of the covariates to the probability of site use of leopards (Panthera pardus).

The solid line represents the posterior mean, and the light grey lines represent the estimated uncertainty based on a random posterior sample of 150–200 iterations. Occupancy probability = site use.