Brief communication: Maximum ingested bite size in captive western lowland gorillas (Gorilla gorilla gorilla).

OBJECTIVES: Previously, we found that maximum ingested bite size (V(b) ), the largest piece of food an animal can consume without biting it into smaller pieces first, isometrically scales relative to body size in strepsirrhines and with negative allometry in anthropoids. In the current study, we rectify the omission of great apes from the earlier sample to now characterize the V(b) of the entire size-range of the order. MATERIALS AND METHODS: Five gorillas (Gorilla gorilla gorilla-G. g. gorilla) were studied to ascertain V(b) in relation to the mechanical properties of five foods. RESULTS: Gorilla V(b) ranged from 166.38 cm(3) (for the least obdurate food: watermelon) to 8 cm(3) (for the most obdurate food: turnip), with an average V(b) of 33.50 cm(3) across all food types. CONCLUSIONS: When these data were compared to those from our previous studies, we found that gorillas consumed relatively slightly smaller volumes of food compared to the trend found across primates. However, because the more frugivorous gorillas consumed relatively larger pieces of food than the large folivorous monkeys previously studied, including the gorilla data increased the slope of the linear regression between body mass and V(b) in anthropoids. Thus, the addition of the largest living primate brings the anthropoid V(b) trend closer to the V(b) trend of the order. Notwithstanding, there is still negative allometry in anthropoid V(b) , in contrast with the isometry in strepsirrhine V(b) . Future research should include species with body masses between the smaller anthropoids and gorillas by studying the V(b) of large papionids and the other great apes.