Habitat differences do not explain population declines of sable antelope in an African savanna

Abstract

Sable antelope, Hippotragus niger, populations have declined substantially in Kruger National Park, South Africa despite large-area protection from land use and poaching. Since Africa’s large mammal populations are restricted to protected areas, understanding how to manage parks for biological diversity is critically important to the sustainability of faunal populations into the future. To better understand the drivers of sable decline, we analyzed landscapes where herds persist in the Pretoriuskop region of Kruger – identified by GPS collar telemetry data from eight individuals in five herds remaining in this area, and compared them to landscapes where sable herds have recently disappeared. We mapped these landscapes with satellite-based spectral data on vegetation greenness and fire frequency and Carnegie Airborne Observatory LiDAR (Light Detection and Ranging) data on 3-D vegetation structure. Within their home ranges, sable herds consistently selected areas with high fire frequency, high tree cover and low shrub cover. However, there were no consistent differences in habitat features between the home ranges of current sable herds and areas formerly supporting herds. Locally deteriorating habitat conditions were therefore not responsible for the decline in sables in this region of the park. Our study also illustrates how multisensor, 3-D mapping of ecosystems provides a means to assess causes and consequences of changing animal habitats over time

Disentangling LiDAR Contribution in Modelling Species–Habitat Structure Relationships in Terrestrial Ecosystems Worldwide. A Systematic Review and Future Directions

“…Studies on birds and invertebrates showed the greatest ecosystem variety (eight and six ecosystems, respectively; Figure 3B), while the remaining taxonomic groups were studied in five different ecosystems. This included six mammal studies in rainforest [10,21,[63][64][65][66], four studies in African savannahs [67][68][69][70], three articles of invertebrates in savannahs [28,71,72], or seven articles of birds in agroecosystems [53,[73][74][75][76][77][78]. Whereas reptile studies were conducted in the rainforest [24], agroecosystem [79], or inland and coastal waters [51], amphibian studies were restricted to seasonal ponds within temperate forests (N = 3).…”

Environmental controls on African herbivore responses to landscapes of fear

“…Metrics of landscape‐level forage quantity for browsers and grazers were derived using remotely‐sensed vegetation cover. For browse quantity, we first measured woody vegetation volume at herbivore‐specific heights (Table 1) across the landscape following Asner et al (2015). We computed a metric of vegetation density from the LiDAR data by first binning and counting the LiDAR returns in a three‐dimensional grid with a step size of 5 × 5 × 0.5 m (defined as voxels), where the first two dimensions of the grid are east and north coordinates and the third is height above ground.…”

Movement ecology of large herbivores in African savannas: current knowledge and gaps

“…They need to be related to habitat features. For example, places no longer supporting sable antelope herds showed no differences in tree cover as revealed by LiDAR imagery from areas within occupied home ranges (Asner et al ), suggesting that features of the grass cover may be more influential. Conditions leading animals to wander beyond their usual home ranges need to be identified, because opportunities for wider space use may be critical for survival during extreme conditions.…”