Habitat use by the wild ungulate, sambar deer (Cervus unicolor) in the shola-grassland ecosystem

Abstract

Habitat use studies help to understand the biological requirements of an organism. The pattern of habitat use is governed by various resources and parameters. The study looked at habitat use by the mammalian herbivore, sambar deer ( Cervus unicolor), a common deer species in an invaded shola-grassland ecosystem in the Western Ghats. Shola-grasslands are threatened ecosystems due to the rapid colonisation by exotics like wattle (Acacia meanrsii). There is limited understanding of how herbivores use this mosaic of forests and grasslands, which are being constantly invaded although these herbivores are shown to affect their dynamics. A qualitative model for habitat use was proposed linking herbivore abundance and predictive habitat parameters such as vegetation height, canopy cover and percentage ground cover. Landscape features such as elevation, distance to water, road, forest patch and wattle plantation were examined to explain the sambar distribution pattern in the landscape and also the faecal matter was collected and analysed for studying the diet composition. Relative ungulate abundance estimation using faecal pellets showed that the land use types are not used in proportion to their cover in the system. Wattle plantations are used the most, shola forests the least and grasslands intermediate. Vegetation composition was able to explain the variation in the pattern in habitat use the most. Stable carbon isotope analysis of sambar faecal matter supported the fact that they are primarily browsers in this landscape and occasionally switch to a mixed diet. Landscape features were insignificant predictors to describe the distribution of sambar d eer. The findings in the study provide insights into interaction of a herbivore with an invasive species which can give pertinent management implications.