NEST-SITE CHARACTERISTICS AND NESTING SUCCESS OF THE MALABAR GRAY HORNBILL IN THE SOUTHERN WESTERN GHATS, INDIA

摘要

We quantified and characterized the nesting habitat of Malabar Gray Horn-bills (Tockus griseus) Dec. 1993—May 1994 in the Anaimalai Hills of southern Western Ghats, India. Twenty-six nest-site variables were recorded in each of 27 nest plots to evaluate variability of nest-site selection. Malabar Gray Hornbills selected nest trees of significantly larger diameter at breast height (DBH 60—89 cm), and greater height of the lowest limb than the associated values from randomly chosen trees. The number of trees of 60—74 cm DBH class was significantly higher in the nest site plots than in the random plots. Most nests were in tall live trees and were formed primarily by heart rot where a branch had broken. Comparison of relative abundance of potential nest cavities and availability of trees in different DBH classes in belt transects indicates that more cavities were formed in trees of larger diameter. Density of potential nest cavities was 10/ha. Malabar Gray Hornbills consistently chose smaller trees than sympatric Great Hornbills (Buceros bicornis). This study indicates the need of mature moist forest habitat for nesting by the Malabar Gray Hornbill.