Hematology and serum biochemistry in wild howler monkeys

Abstract

Hematological and blood biochemistry parameters are valuable tools for determining the health of free-ranging primate populations. However, baseline data on these parameters are needed to discriminate between healthy and unhealthy individuals. This type of information is currently limited for wild primate populations and especially for those that cannot be easily kept in captivity. This is particularly true for howler monkeys. The aim of this chapter is twofold. First, we review the hematological and serum biochemistry values of free-ranging individuals of three howler monkey species, Alouatta pigra and A. palliata from Mexico and A. macconnelli from French Guiana, in order to establish reference values for these species. We also obtain published data for two populations of black and gold howler monkeys (A. caraya). Second, we infer the health status of each population highlighting the benefits of blood screening as a tool to evaluate the responses of howler monkeys to the disturbance of their habitats. We found the following patterns: (A) females have higher concentration of white blood cell (WBC) count than males with the exception of A. caraya, (b) A. palliata and A. caraya have higher concentration of WBC count with respect to the other Alouatta species, (c) Mexican howler monkeys (A. palliata and A. pigra) have low total protein concentration with respect to other Alouatta species, and d) creatinine concentration is higher in males possibly due to their higher body mass. Overall, the present study will help to monitor blood parameters in threatened wild howler monkey populations as well as in captive individuals.