Gillespie and co-authors Colin A. Chapman of McGill University in Canada and Ellis C. Greiner of the University of Florida found that red-tailed guenons had a much higher prevalence of infection with seven gastrointestinal parasites in the logged forest than in the undisturbed one.
The parasites found in the guenons were Trichuris sp. (whipworms), Oesopohagostomum sp. (nodular worms), Entamoeba coli, Entamoeba histolytica, Iodamoeba buetschlii, Strongyloides fulleborni and Streptopharagus sp.
Additionally, the red-tailed guenons in the logged forest were the only primates of the three species infected with Chilomastix mesnilia, Giardia lambila and a Dicrocoeliid liver fluke. These parasites did not appear in guenons in the undisturbed forest.
The researchers also noted that the patterns of forest regeneration in the aftermath of logging appear to be more favorable for colobus monkeys than for the guenons. Citing their own as-yet unpublished data, and that of Karen Rode of Washington State University, the researchers suggest that reduced food availability has led to dietary stress. The guenons in the logged forest, they report, are getting much less protein and vital minerals than their counterparts in undisturbed forests.
Recovery of the forest also has been hampered by the growth of acanthus, an invasive shrub that has overwhelmed much of the forest floor where trees were removed, Gilllespie said. Because elephants love to eat the shrub, they trample through the clearings, adding yet another obstacle for the growth of new trees, he said.
"Knowledge of how particular species are affected by various forms of ecological change is essential to promote land-use policy that is compatible with animal and human health and biodiversity conservation," Gillespie, Chapman and Greiner wrote in the conclusion of their study.