ESR 3:321-329 (2007)  -  DOI: https://doi.org/10.3354/esr00055

ABSTRACT: Endangered white-headed langurs Trachypithecus leucocephalus (leaf monkeys) live on limestone hills in southwestern Guangxi, China. This terrain is unsuitable for using published census techniques to estimate langur population density, and the precision of unpublished techniques used in the past is unproven; yet reliable estimates are crucial for conservation planning. In this paper, we discuss existing censusing techniques in the context of their potential suitability for estimating the population of white-headed langurs; we introduce methods for partition-spot surveys and modified line-transect sampling; we validate the resulting data and recommend 2 techniques for future use. We show that partition-spot surveys provide accurate information on the number of langurs and their locations, but that modified line-transect sampling is more time-efficient. While validating our techniques, we documented an increase in the langur population of one hill cluster between 1998 and 2003.

KEY WORDS: Censusing · China · Conservation · Limestone hills · White-headed langurs