The effects of feeding frequency on jaw loading in two lemur species

Studies on oral processing are often snapshots of behaviors that examine feeding through individual bouts. In this study, we expand on our previous work comparing bite/chew variables per feeding bout to summed daily biting, chewing, and food intake to interpret loading that could have potential morphological effects.

We observed sympatric Lemur catta and Propithecus verreauxi over two field seasons in the dry forest of Bezà Mahafaly Special Reserve in southwestern Madagascar. Bite and chew rates determined from videos filmed during observations were multiplied with time spent feeding on specific foods during focal follows to calculate daily values for each feeding bout. Food mechanical properties (FMPs) were tested on dietary items with a portable tester. We contrasted daily bite/chew numbers and intake with FMPs, species, season, and food shape.

Daily bite and chew numbers increased with maximum, but not average, food toughness. Daily intake decreased with average and maximum toughness. Season had a strong effect on daily bites and chews, but not on intake. Food shape influenced intake and total bite and chew numbers. The lemur species did not differ in our models.

Maximum food toughness impacted feeding behaviors and intake, which is consistent with higher loads having a greater effect on morphology. In contrast to feeding per bout, cumulative biting and chewing did not differ between species; taking feeding frequency into consideration affects interpretation of jaw loading. Finally, biting, as much as chewing, may generate strains that impact morphology.