The Nutritional Geometry of Resource Scarcity: Effects of Lean Seasons and Habitat Disturbance on Nutrient Intakes and Balancing in Wild Sifakas

Abstract

Animals experience spatial and temporal variation in food and nutrient supply, which may cause deviations from optimal nutrient intakes in both absolute amounts (meeting nutrient requirements) and proportions (nutrient balancing). Recent research has used the geometric framework for nutrition to obtain an improved understanding of how animals respond to these nutritional constraints, among them free-ranging primates including spider monkeys and gorillas. We used this framework to examine macronutrient intakes and nutrient balancing in sifakas (Propithecus diadema) at Tsinjoarivo, Madagascar, in order to quantify how these vary across seasons and across habitats with varying degrees of anthropogenic disturbance. Groups in intact habitat experience lean season decreases in frugivory, amounts of food ingested, and nutrient intakes, yet preserve remarkably constant proportions of dietary macronutrients, with the proportional contribution of protein to the diet being highly consistent. Sifakas in disturbed habitat resemble intact forest groups in the relative contribution of dietary macronutrients, but experience less seasonality: all groups’ diets converge in the lean season, but disturbed forest groups largely fail to experience abundant season improvements in food intake or nutritional outcomes. These results suggest that: (1) lemurs experience seasonality by maintaining nutrient balance at the expense of calories ingested, which contrasts with earlier studies of spider monkeys and gorillas, (2) abundant season foods should be the target of habitat management, even though mortality might be concentrated in the lean season, and (3) primates’ within-group competitive landscapes, which contribute to variation in social organization, may vary in complex ways across habitats and seasons.

The effects of plant nutritional chemistry on food selection of Mexican black howler monkeys (Alouatta pigra): The role of lipids

“…Our study indicates that, contrary to the view that howler monkeys are characterized by a low-energy diet and that the protein-to-fiber ratio is a good predictor of their food choice, black howler monkeys adopted a strategy which allowed them to consume, during certain periods of the year, leaves low in available protein or high in fiber. Our results add to the increasing evidence that primates use multiple strategies [Felton et al, 2009;Irwin et al, 2015Rothman et al, 2011Behie & Pavelka, 2012a] to reach their nutritional and energetic requirements and do so by mixing food items that vary in nutrients, minerals, antifeedants, and energy.…”

Nutrient‐specific compensation for seasonal cold stress in a free‐ranging temperate colobine monkey

“…A detailed study of a single female chacma baboon ( Papio hamadryas ursinus ) showed that this individual maintained a similar dietary macronutrient ratio across 30 consecutive days, despite eating different combinations of foods on different days (Johnson, Raubenheimer, Rothman, Clarke, & Swedell, ). Other studies, including those of mountain gorillas (Raubenheimer, Machovsky‐Capuska, Chapman, & Rothman, ; Rothman, Raubenheimer, & Chapman, ), black howler monkeys ( Alouatta pigra ) (Righini, ) and sifaka lemurs ( Propithecus diadema ) (Irwin, Raharison, Raubenheimer, Chapman, & Rothman, ), also support the contention that wild primates target a particular balance of macronutrients across a single day or across multiple days.…”

Motive for Killing: What Drives Prey Choice in Wild Predators?

“…) and sifakas ( Propithecus diadema , Irwin et al. ), and the more omnivorous chacma baboon ( Papio hamadryas ursinus, Johnson et al. ).…”