Habitat thresholds for successful predation under landscape change
- September 7, 2022
- by Atkinson, H., Cristescu B., Marker L. L., Rooney N.
Habitat loss and alteration affect wildlife populations worldwide. Bush encroachment alters landscapes and threatens arid and semi-arid grasslands, but its effects on predator–prey relationships and carnivore community ecology are not well understood. Predation strategies of large predators, for example, high-speed pursuits versus ambush from short distances, are likely to be affected differently by bush encroachment.
We assessed how bush encroachment affects the overall predation success of cheetahs (Acinonyx jubatus) and leopards (Panthera pardus) in a savanna landscape under variable fractional woody cover (FWC). We tested if predation success remained relatively unchanged for leopards across a gradient of FWC and whether cheetah predation was most successful at low to intermediate cover and varied seasonally.
Belly scores of predators were measured from camera-trap images collected over 7 years in north-central Namibia and used to index predation success. We derived predicted belly score probabilities as a function of FWC, which was measured using a Synthetic Aperture Radar (SAR)-derived satellite data layer.
Predicted leopard predation success was highest at 0.27–0.34 FWC in the dry season, potentially due to lower prey density in highly covered areas and decreased prey catchability in low cover. Predicted cheetah predation success was highest at 0.24–0.28 FWC in the wet season, potentially due to increased landscape openness, high availability of habitat margins for visualizing and stalking prey, and decreased kleptoparasitism by leopards. These results highlight optimal habitat cover thresholds that favor lower FWC for cheetahs than for leopards.
The findings indicate that landscape heterogeneity is important for the predation success of cheetahs and leopards, suggesting that habitat management should focus on bush control efforts to maintain intermediate levels of bush cover.