TEMPORAL OVERLAP IN ACTIVITY PATTERN BETWEEN NATIVE BLACKBUCK AND INVASIVE FERAL-HORSE AT POINT CALIMERE WILDLIFE SANCTUARY, SOUTHERN INDIA

Abstract

Assessing temporal pattern of activity is essential to understand the niche partitioning and organisation of animal communities. Sympatric species that use the same resources cannot coexist for long without one competitively excluding the other. Feral-horse, an invasive species, overlaps in diet and distribution area with blackbuck at Point Calimere, Southern India. Temporal partitioning in activity between them could at least avoid interference competition and help in coexistence. This study compared the daylight activities of blackbuck and feral-horse collected following instantaneous scan sampling method between October 2017 and November 2019, to determine if temporal partitioning exist between them. Analysis of scan data (n = blackbuck – 5982, feral-horse – 3542 scans) show that among five major activities, extent of time spent on feeding, vigilance and other activities did not vary, while resting, moving and socialising time did vary between them. Further, analysis of time activity pattern data using Kernel temporal density overlap estimates and compare activity level test in R showed that feeding activity had the highest coefficient overlap with insignificant temporal difference, followed by vigilance and other activities. The coefficient overlap on moving, resting and social activities varied significantly indicating that these activities did not overlap temporally between the two species. However, the spatiotemporal overlap in activities, especially on feeding along with reported dietary overlap by invasive feral-horse with native blackbuck, could be the significant contributing factor to the reported reduced fitness of the blacbuck population at Point Calimere. Therefore, management concerned needs to consider reducing the effect of the invasive feral-horse on the native balckbucks, as suggested.