Measuring Indian Blackbuck Antilope cervicapra (Mammalia: Cetartiodactyla: Bovidae) abundance at Basur Amruth Mahal Kaval Conservation Reserve, Chikkamagaluru, southern India

Abstract

Grasslands are among the most critically endangered ecosystems in the tropics, but they are often treated as wastelands and conservation efforts are seldom directed towards these landscapes. The Blackbuck Antilope cervicapra is a large wild herbivore found in most grassland ecosystems across India. Despite their critical role in their trophic web, there are no reliable estimates of Blackbuck populations from their geographic range that takes detection probability into consideration. In this study, we conducted field surveys to estimate Blackbuck density in Basur Amruth Mahal Kaval Conservation (BAMKCR) with an area of 7.36km2 in southern India. We surveyed Blackbucks for a week in July 2014 along straight line transects between 09:00–12:00 hr and used the distance sampling approach to address the imperfect detection. A total of three transect lines of lengths 3.01km, 2.4km and 1.2km were sampled for seven temporal replicates. With an effort of 46.27km, 56 sightings of Blackbucks were recorded that was analyzed using the program DISTANCE. With a detection probability of 0.58 (0.053 SD) the estimated density of Blackbuck was 26.23 (6 SD) individuals/km2. The derived abundance estimate was 193 (c. 148–238) individuals in the study area. Our results show implications of a statistically robust design that accounts for imperfect detection. It provides an insight into a resident population of Blackbucks in a dynamic and fragile habitat. Blackbuck density estimate from this study sets the background for periodic monitoring of their populations, examination of the impacts of habitat modifications and gauge long-term viability of the grassland habitat in BAMKCR.

Keywords

• density estimation
• distance sampling
• habitat modification
• imperfect detection
• long-term viability
• monitoring.