Oral Processing of Three Guenon Species in Taï National Park, Côte d’Ivoire

Simple Summary Diana monkeys, Campbell’s monkeys, and Lesser spot-nosed guenons in Taï National Park, Côte d’Ivoire, are three closely related species that regularly form associations, and consume a diet with significant overlap. We took advantage of this dietary overlap and anatomical similarity to examine how closely related species process the same food items. We quantified the frequency of oral-processing behavior (use of incisors, canines, and post-canine chewing) each time foods were introduced to the mouth of these three taxa. We determined that these species use different oral-processing profiles while eating the same foods, which is surprising and intriguing since they are closely related and morphologically very similar. While our sample does not encompass the breadth of these species’ diets, it does suggest that substantial differences in the ways different taxa process food items may not be reflected in dental or facial anatomy. Abstract Three guenon species in Taï National Park frequently form and maintain stable polyspecific associations despite significant feeding competition. This dietary overlap provides an opportunity to examine how closely related and anatomically similar taxa process the same foods. Our research examines whether the oral-processing behaviors of these guenons differ when they consume the same foods. Methods: Data on oral-processing behavior were collected on one habituated group each of Cercopithecus campbelli, C. diana, and C. petaurista in Taï National Park, Côte d’Ivoire from January 2016 to December 2018. We recorded the frequency with which foods were introduced to the mouth (ingestive action) and the frequency with which foods were processed using incisors, canines, and postcanine teeth. Oral-processing profiles for species-specific plant foods, fungi, and invertebrates were compared using Monte Carlo resampling. We quantified oral-processing behavior during a total of 2316 five-minute focal periods. Diana monkeys use their incisors significantly more per ingestive action than Campbell’s monkeys or Lesser spot-nosed guenons. Lesser spot-nosed guenons use their incisors more than Campbell’s monkeys. Diana monkeys also use significantly more post-canine chews per ingestive action than Campbell’s monkeys and Lesser spot-nosed guenons. Lesser spot-nosed guenons generally use fewer post-canine chews than Diana monkeys but more than Campbell’s monkeys. Canine use during feeding was rare in all three taxa. The three study species use different oral-processing profiles when consuming the same foods. These results are intriguing given the overall similarity in dental and cranial anatomy in these taxa. The oral-processing profiles we report do not encompass the full dietary breadth of all species; however, the behavioral diversity demonstrated during consumption of the same foods suggests that insight into feeding behavior is more likely obtained by examining oral processing of individual foods rather than broad food categories. Furthermore, these results underscore that important variation in feeding behavior is not necessarily associated with morphological differences in dental or craniofacial anatomy.