Foraging strategies underlying bird egg predation by macaques: A study using artificial nests

Area of Science:

• Ethology
• Primatology
• Ecology

Background:

• Bird nest predation by non-human primates is common, yet primate foraging strategies for nests remain poorly understood.
• Birds utilize specific microhabitats and nest types to evade predation, a primary cause of nesting failure in tropical regions.

Purpose of the Study:

• To investigate whether nest predation by northern pigtailed macaques (Macaca leonina) is a selective or opportunistic feeding behavior.
• To determine the influence of nest type, microhabitat characteristics, and nest height on macaque predation rates.

Main Methods:

• Utilized artificial nests (open-cup and cavity) placed in various microhabitats within the Sakaerat Biosphere Reserve, Thailand.
• Employed camera traps to monitor predation events by a troop of northern pigtailed macaques.
• Assessed factors including understory density, canopy cover, canopy height, ground cover, presence of thorns/lianas, and nest height.

Main Results:

• Northern pigtailed macaques plundered 112 out of 200 artificial nests, demonstrating high predation rates.
• Predation rates decreased significantly with increasing nest height.
• Nest type and microhabitat characteristics did not significantly influence macaque predation, suggesting active searching across different environments.

Conclusions:

• Nest predation by northern pigtailed macaques appears to be a selective feeding behavior, driven by active searching rather than solely opportunistic encounters.
• The findings suggest significant conservation implications for forest-dwelling bird populations due to macaque predation.
• Traditional behavior observation methods may underestimate primate nest predation due to the cryptic nature of this behavior.