Effect of habitat quality on the ecological behaviour of a temperate-living primate: time-budget adjustments

Abstract

Barbary macaques, like other non-human primates living in highly seasonal temperate environments, display high monthly variations in their diet. In addition, their diet changes according to the habitat type they colonize and to the degree of habitat degradation due to resource exploitation by local people, in particular through pastoralism. We studied the time-budget adjustments of wild Barbary macaques in three cedar-oak forests impacted by different intensities of grazing pressure from goats and sheep. We examined how diet variations influenced the time monkeys spent in their activities and their day range lengths (i.e. their energy costs). At three studied sites, diet composition and time budgets showed marked seasonal variations. Diet composition had a strong influence on monkeys' time budget. In the forest where pastoralism was the highest, diet included a greater proportion of underground resources, shrub fruit and acorns, which led to an increase in the time spent foraging and moving, as well as an important increase in day range lengths. Energy costs were therefore higher in a degraded environment than in a suitable habitat. The monkeys living in forests subjected to pastoralism took advantage of increased day lengths to spend more time searching for food. However, in the forest with the highest pastoralism pressure, although monkeys spent more time foraging, they spent less time feeding than monkeys at the other sites. In addition, they appeared to have reached the limits of the available time they could devote to these activities, as their diurnal resting time was at its lowest level over several months. Temperature variations did not appear to modify monkeys' time budgets. In the least favourable habitat, saving time from resting activity allowed monkeys to maintain a relatively high level of social activity, partly linked to rearing constraints.

Effect of habitat quality on diet flexibility in Barbary macaques

“…At the same time, they avoid food items that are available year-round such as cedar leaves. However, by foraging on scarce, difficult-to-excavate foods, monkeys increase their energy costs by spending more time foraging and moving, and increasing group's day range lengths [Ménard et al, 2013]. Our findings suggest that Barbary macaques adopt an energy-maximizing strategy in the summer period of food scarcity, confirming previous studies performed during a comparable time of year [Ménard & Vallet, 1997].…”

“…As Barbary macaques spend more than 50% of their mean annual feeding time on resources from the herbaceous layer [Ménard & Vallet, 1986], domestic herbivores such as sheep and goats that feed on the herbaceous plants are severe ecological competitors. Indeed, in forests where overgrazing was the highest, Barbary macaques increased their foraging and moving time, as well as daily travel distances (i.e., their energy costs), and spent less time feeding (i.e., ingesting food) than monkeys in less disturbed forests [Ménard et al, 2013]. Moreover, a recent study shows a negative correlation between livestock grazing intensity and monkey density, which suggests that monkeys could no longer find enough resources in forests where grazing pressure was high [Ménard et al, 2014].…”

Anthropogenic influences on the time budgets of urban vervet monkeys

“…We used focal animal sampling techniques (Altmann, 1974) to observe each individual for 20 min., sampling all group members before repeating observations in each month. We chose four key mutually exclusive categories to represent time budget foraging, movement, resting, social defined as foraging: a monkey actively searching for food items before feeding and directly consuming food items found (food items include, plants, aesthetic garden plants and human derived food) (Ménard et al, 2013;Saj et al, 1999); movement: included all types of locomotion not associated with any other activity, for example walking, running, climbing, and jumping (Ménard et al, 2013;Saj et al, 1999); resting: monkey in an inactive posture that excludes interacting with others, in a motionless position for longer than five seconds (Saj et al, 1999); social: monkey interacting with at least one other monkey including both affiliative and agnostic behaviors (Ménard et al, 2013;Saj et al, 1999).…”

Migration Load, Ecological Opportunity, and Obsessive Compulsive Personality Disorder Etiology: Obsessive Character as an Adaptation to Seasonality

“…Anthropogenic impoverishment or enrichment of natural environments has been demonstrated to aggravate or ease time stress among primates (Menon and Poirier 1996;Saj et al 1999;Li and Rogers 2004;Van Doorn et al 2010;Ménard et al 2013). Observation suggests that within tropical environments, unfavorable local conditions can make time budgeting more strict and spare; for example, aridity induces time stress among baboons (Dunbar 1992), while orangutans living in peat swamps experience more time stress relative to those living in masting dipterocarp forests (Morrogh-Bernard et al 2009).…”