Biodiversity and Conservation

, Volume 28, Issue 4, pp 847–862 | Cite as

Standardizing methods to estimate population density: an example based on habituated and unhabituated spider monkeys

  • Denise SpaanEmail author
  • Gabriel Ramos-Fernández
  • Colleen M. Schaffner
  • Sandra E. Smith-Aguilar
  • Braulio Pinacho-Guendulain
  • Filippo Aureli
Original Paper


Population estimates are critical for making informed conservation decisions. However, methods for data collection and analysis of population estimates from wildlife surveys vary, often preventing comparisons between sites or years. In this study we compared population density estimates of spider monkeys, Ateles geoffroyi, derived from four commonly used methods to the actual density estimate based on known individual monkeys and home-range size and corroborated these results with surveys done on unhabituated monkeys in the same area. We recorded perpendicular distances of individual monkeys in the Otoch Ma’ax yetel Kooh Protected Area during two surveys: within the home range of an individually-recognized spider monkey group (survey one) and largely outside of the home range (survey two). We sighted 278 and 76 spider monkeys for a total effort of 93.74 and 42.78 km in surveys one and two, respectively. The actual density estimate was 65.4 individuals/km2 (survey one). This value lies closer to the population density estimate obtained using the Kelker method (58.2 individuals/km2) than conventional distance sampling (CDS; 92.9–93.8 individuals/km2). Density estimates obtained with King and maximum perpendicular distance methods deviated substantially from the actual density. Population density estimates using the Kelker method and CDS differed less in survey two. Population density estimates differed little whether transects were walked slow or fast. We recommend using the Kelker method and CDS to estimate population density with a correction for distance estimation errors. We demonstrate how studies on populations of known size can improve the methods to survey populations of unknown size.


Population monitoring Kelker method Conventional distance sampling Spider monkeys 



We would like to thank our field assistants Anthony Denice, Augusto Canul, Eulogio Canul, Macedonio Canul and Juan Canul for assistance with data collection. We thank Martha Bonilla-Moheno, Jorge Morales-Mavil, Sonia Gallina-Tessaro and Salvador Mandujano for input on analyses. We thank the Secretaria del Medio Ambiente y Recursos Naturales (SEMARNAT) and the Comisión Nacional de Áreas Naturales Protegidas (CONANP) for permission to work in the Protected Area. We would also like to thank the Consejo Nacional de Ciencia y Tecnologia (CONACYT: CVU: 637705), Chester Zoo, Comisión Nacional de Áreas Naturales Protegidas (PROCER/DRPYyCM/2/2015), the Instituto Politécnico Nacional, the Centro de Ciencias de la Complejidad of the Universidad Nacional Autónoma de Mexico and the Instituto de Neuroetología of the Universidad Veracruzana for financial and logistical support.

Compliance with ethical standards

Conflict of interest

The authors declare that they have no conflict of interest.

Research involving animal rights

The research presented in the manuscript adhered to the Association for the Study of Animal Behaviour Guidelines for the Use of Animals in Research and Teaching.

Supplementary material

10531_2018_1696_MOESM1_ESM.xlsx (28 kb)
Supplementary material 1 (XLSX 28 kb)


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Copyright information

© Springer Nature B.V. 2019

Authors and Affiliations

  1. 1.Instituto de NeuroetologíaUniversidad VeracruzanaXalapaMexico
  2. 2.ConMonoMaya A.C.ChemaxMexico
  3. 3.Instituto de Investigaciones Sobre Recursos NaturalesUniversidad Michoacana de San Nicolás de HidalgoMoreliaMexico
  4. 4.Unidad Interdisciplinaria en Ingeniería y Tecnologías AvanzadasInstituto Politécnico NacionalMexico CityMexico
  5. 5.Instituto de Investigaciones en Matemáticas Aplicadas y en SistemasUniversidad Nacional Autónoma de MexicoMexico CityMexico
  6. 6.Psychology DepartmentAdams State UniversityAlamosaUSA
  7. 7.Conservación Biológica y Desarrollo Social A.C.Mexico CityMexico
  8. 8.Departamento de Ciencias de la SaludUniversidad Autónoma MetropolitanaMexico CityMexico
  9. 9.Centro Interdisciplinario de Investigación para el Desarrollo Integral Regional Unidad OaxacaInstituto Politécnico NacionalOaxacaMexico
  10. 10.Conservación de la Biodiversidad del Usumacinta A. C.Emiliano ZapataMexico
  11. 11.Research Centre in Evolutionary Anthropology and PalaeoecologyLiverpool John Moores UniversityLiverpoolUK

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