The occurrence of arboreal mammals in the rain forest fragments in the Anamalai Hills, south India

Abstract

The occurrence and abundance of five species of arboreal mammals in 25 rain forest fragments ranging from <1 ha to 2500 ha in area in the Anamalai Hills in south India, were examined in relation to several habitat and landscape variables. The lion-tailed macaque ( Macaca silenus) was the most affected, being absent from 15 fragments while the Nilgiri langur ( Trachypithecus johnii) was absent from six and the Malabar giant squirrel ( Ratufa indica) from only three fragments. The densities of the giant squirrel, the large brown flying squirrel ( Petaurista petaurista) and the Travancore flying squirrel ( Petinomys fuscocapillus) increased with decreasing area and increasing disturbance level. In logistic regression, canopy height and tree density were the best predictors of the occurrence of the lion-tailed macaque and the Nilgiri langur, respectively. Area of the fragment may be an important predictor of occurrence of these species only when the fragments are very small. Once initially present, their continued occurrence is better predicted by habitat variation, consistent with the ecology of the species. It is possible to retain the arboreal mammals in the rain forest fragments through improving habitat quality. The suggested measures include (a) prevention of degradation due to lopping and felling of trees; (b) assisted regeneration in forest fragments; and (c) retention of orchards of jack fruit trees ( Artocarpus integrifolia), guava ( Psidium guajava), etc., in the labour settlements around the fragments. Land use policies that would prevent conversion of cardamom plantations into tea or coffee plantations are also needed.