Sleeping site selection and presleep behavior in wild pigtailed macaques

Area of Science:

• Primate behavior
• Behavioral ecology
• Conservation biology

Background:

• Nonhuman primates' sleeping site selection is influenced by environmental factors like predation risk and food resource distribution.
• Understanding these factors is crucial for primate conservation and behavioral studies.

Purpose of the Study:

• To investigate the sleeping site selection and presleep behavior of northern pigtailed macaques (Macaca leonina).
• To determine the influence of predation risk and food resource location on their sleeping habits.

Main Methods:

• Field observation of a northern pigtailed macaque troop in Khao Yai National Park, Thailand, over 154 nights (April 2009 - November 2010).
• Recording sleeping site characteristics, location, individual placement within trees, posture, and behavior.
• Analyzing the proximity of sleeping sites to feeding trees and human settlements.

Main Results:

• Macaques preferred tall trees (mean height 20.9m) and high sleeping locations (mean height 15.8m), suggesting an anti-predator strategy.
• Sleeping sites were often located near the last or first feeding trees of the day, potentially saving energy and reducing predation risk during foraging.
• Proximity to human settlements facilitated access to anthropogenic food sources during fruit scarcity.
• A temporal pattern of sleeping site use indicated a preference for specific sites but infrequent reuse on consecutive nights, balancing predator avoidance, travel costs, and familiarity.

Conclusions:

• Sleeping site selection in northern pigtailed macaques is a complex strategy balancing predation avoidance, energy conservation, and resource access.
• The findings highlight the adaptability of macaques to varying environmental conditions, including proximity to human activity.
• These insights are valuable for understanding primate behavioral ecology and informing conservation efforts in human-modified landscapes.