Study of the folivore diet of the black howler monkey (Alouatta caraya) by means of the microscopical analysis of the faeces

Abstract

Study of the folivore diet of the black howler monkey (Alouatta caraya) by means of the microscopical analysis of the faeces. A study of the diet of the black howler monkey (Alouatta caraya) was conducted in the flooded forest of the Parana River, in the northeastern region of Argentina. Howler monkeys have arboreal habits, and leaves and fruits constitute the major bulk of the diet. The diet composition of A. caraya was studied by means of microscopical analysis comparing epidermical characters of remains of leaves from faeces, and those coming from trees and vines. The technique requires the previous anatomical study of the vegetation living in the studied area. Samples of fresh leaves and faeces were obtained during the autumn and spring of 1997. For fecal samples the identity, age and sex of individuals were considered. Results obtained allowed to define the qualitative composition of the diet, that includes Tessaria integrifolia, Croton urucurana, Cathormion polyanthum, Inga urugüensis, Cecropia pachystachya, Eugenia burkartiana, Iseia luxurians, Ipomoea rubens, Houssayanthus incanus and Cissus palmata. This methodology could be a useful tool to assess the reliability of records of feeding habits obtained by behavioural studies, and discover some rare items that are very difficult to detect by direct observation