TY - JOUR
T1 - How Survey Design Affects Monkey Counts
T2 - A Case Study on Individually Recognized Spider Monkeys (Ateles geoffroyi)
AU - Spaan, Denise
AU - Ramos-Fernández, Gabriel
AU - Schaffner, Colleen M.
AU - Pinacho-Guendulain, Braulio
AU - Aureli, Filippo
N1 - Publisher Copyright:
© 2017 © 2017 S. Karger AG, Basel. Copyright: All rights reserved.
PY - 2018/1/1
Y1 - 2018/1/1
N2 - The fast movement and high degree of fission-fusion dynamics of spider monkeys (Ateles spp.) make them notoriously difficult to survey. We examined which aspects of survey design affect spider monkey sightings along transects in a group of individually recognized spider monkeys (Ateles geoffroyi) in Punta Laguna, Yucatan, Mexico. We calculated the number of monkeys and subgroups sighted per transect walk. Using generalized linear models, we found no effect of the number of observers, transect type (new vs. existing), walking speed, or time of day on individual monkey counts or subgroup counts. Recounting of individuals was relatively rare and occurred when transects were walked relatively slowly. We missed more young than adult monkeys. The group composition based on survey data was similar to the known group composition. Based on our findings we recommend that surveys performed on relatively flat terrain be conducted at speeds similar to or faster than the moving speed of spider monkeys to minimize recounting of individuals and that young:adult female ratios based on survey data be interpreted as conservative indicators of population health. The novel methods presented to determine sources of bias in population estimates are applicable to a wide range of primates that are difficult to survey.
AB - The fast movement and high degree of fission-fusion dynamics of spider monkeys (Ateles spp.) make them notoriously difficult to survey. We examined which aspects of survey design affect spider monkey sightings along transects in a group of individually recognized spider monkeys (Ateles geoffroyi) in Punta Laguna, Yucatan, Mexico. We calculated the number of monkeys and subgroups sighted per transect walk. Using generalized linear models, we found no effect of the number of observers, transect type (new vs. existing), walking speed, or time of day on individual monkey counts or subgroup counts. Recounting of individuals was relatively rare and occurred when transects were walked relatively slowly. We missed more young than adult monkeys. The group composition based on survey data was similar to the known group composition. Based on our findings we recommend that surveys performed on relatively flat terrain be conducted at speeds similar to or faster than the moving speed of spider monkeys to minimize recounting of individuals and that young:adult female ratios based on survey data be interpreted as conservative indicators of population health. The novel methods presented to determine sources of bias in population estimates are applicable to a wide range of primates that are difficult to survey.
KW - Ateles geoffroyi
KW - Fission-fusion dynamics
KW - Missing individuals
KW - Population monitoring
UR - http://www.scopus.com/inward/record.url?scp=85035800322&partnerID=8YFLogxK
U2 - 10.1159/000481796
DO - 10.1159/000481796
M3 - Artículo
C2 - 29190614
SN - 0015-5713
VL - 88
SP - 409
EP - 420
JO - Folia Primatologica
JF - Folia Primatologica
IS - 5
ER -