Competition for food in a solitarily foraging folivorous primate (Lepilemur leucopus)?

Abstract

Group-living folivorous primates can experience competition for food, and feeding competition has also been documented for solitarily foraging gummivorous and omnivorous primates. However, little is known about the types and consequences of feeding competition in solitary folivorous foragers. We conducted this study in the spiny forest of Berenty Reserve, southern Madagascar, to characterize the competitive regime of the nocturnal solitarily foraging white-footed sportive lemur (Lepilemur leucopus), a species that lives in dispersed pairs. We analyzed 1,213 hr of behavioral observations recorded simultaneously for the male and female of each of seven social units and recorded seasonal changes in food availability over a complete annual cycle. Lepilemur leucopus exhibited low selectivity in its dietary choice and mainly included the most abundant plant species in its diet. Contrary to our predictions, we did not find evidence for increased rates of contest (i.e., displacement from food trees) or scramble competition (i.e., shared use of food patches) during the lean season, neither within nor between social units. Instead, conflict rates were low throughout the year, and, during these observations, any feeding stress may have been more related to food quality than quantity. The resource defense hypotheses may not explain pair-living in this species as there was no indication that males defend food resources for their female pair-partners. The observed lack of feeding competition may indicate that a cryptic anti-predator strategy is a better predictor of spatial avoidance of pair-partners than conflict over food. While anti-predator benefits of crypsis may explain, at least partly, female-female avoidance, studies on the relationship between territory size/quality and reproductive success are required to understand whether feeding competition reduces the potential for female association in L. leucopus.

Keywords: crypsis; feeding competition; predation; resource defense; seasonality; spatial avoidance.

Figure 1

Seasonal food availability based on 25 identified tree species that were used as a food sources by L. leucopus (ML, mature leaves; YL, young leaves; OL, old leaves; Fl, flowers; Fr, fruits).

Figure 2

Boxplots showing medians and quartiles of the proportions of total observation time Lepilemur leucopus spent eating (A), resting (B) and traveling (C) across four seasons (N = 14; multilevel modeling (MLM) for repeated measures, *P < 0.05, **P < 0.01, ***P < 0.001).