How Survey Design Affects Monkey Counts: A Case Study on Individually Recognized Spider Monkeys (Ateles geoffroyi)

Area of Science:

• Primatology
• Wildlife Survey Methods
• Conservation Biology

Background:

• Spider monkeys (Ateles spp.) exhibit complex social structures and rapid movement, complicating accurate population surveys.
• Effective survey designs are crucial for understanding primate populations and informing conservation strategies.
• Previous survey methods for spider monkeys have not adequately addressed biases introduced by their behavior.

Purpose of the Study:

• To identify key survey design elements influencing spider monkey (Ateles geoffroyi) sighting rates and accuracy.
• To provide evidence-based recommendations for optimizing spider monkey survey protocols.
• To develop adaptable methods for surveying other elusive primate species.

Main Methods:

• Conducted transect surveys with individually recognized spider monkeys (Ateles geoffroyi) in Punta Laguna, Yucatan, Mexico.
• Varied survey parameters including observer number, transect type, walking speed, and time of day.
• Utilized generalized linear models to analyze the impact of survey design on monkey and subgroup counts.

Main Results:

• Survey design elements like observer number, transect type, walking speed, and time of day did not significantly affect monkey or subgroup counts.
• Slower walking speeds increased the likelihood of recounting individuals.
• Young monkeys were more likely to be missed during surveys than adults.

Conclusions:

• Conducting surveys at speeds equal to or faster than spider monkey movement is recommended to minimize recounting.
• Survey data on young-to-adult female ratios should be interpreted cautiously as conservative indicators of population health.
• The presented methodology offers a framework for refining survey biases in difficult-to-study primate populations.