Prevalence and Intensity of Intestinal Parasites in Mantled Howling Monkeys (Alouatta palliata) in Northeastern Costa Rica: Implications for Conservation Biology

TLDR: The prevalence of parasitic infection observed in howlers at La Selva (100%) is higher than has been reported for bowlers in a dry deciduous forest at La Pacifica, Costa Rica (47%).

Abstract: I examined the prevalence and intensity of intestinal parasitic infections in a population of mantled howling monkeys (Alouatta palliata) at La Selva Biological Reserve, a rainforest in northeastern Costa Rica. I collected fresh fecal samples from individual bowler monkeys from two focal troops from October 1991 through October 1992. The presence of parasite ova and larvae in samples was determined by using a formalin-ethyl acetate sedimentation technique. Three types of endoparasites were found: (1) a roundworm, Parabronema sp., (2) a physalopterid roundworm, species undetermined, and (3) a fluke, species undetermined. No differences were found in the prevalence of parasitic infections between sexes or troops. No statistical differences were found between the sexes for the intensity of infection. The troop that lived along the river showed a statistically significant higher intensity of nematode infection than the troop that lived mostly in primary forest. Parabronema sp. was found only from individuals in the river group. The prevalence of parasitic infection observed in howlers at La Selva (100%) is higher than has been reported for bowlers in a dry deciduous forest at La Pacifica, Costa Rica (47%). Microclimatic factors, ranging patterns, and home-range size are identified as important variables that may affect parasitic infections of howler populations. Data from this study suggest that narrow corridor designs may be inappropriate for conservation of primates and possibly other species of arboreal animals.