International Journal of Primatology

, Volume 32, Issue 4, pp 878–888 | Cite as

Population Density Estimates of the Critically Endangered Yellow-tailed Woolly Monkeys (Oreonax flavicauda) at La Esperanza, Northeastern Peru

  • Sam Shanee
  • Noga Shanee


The critically endangered yellow tailed woolly monkeys (Oreonax flavicauda, Humboldt 1812) are endemic to the cloud forests of northeastern Peru. We surveyed populations of Oreonax flavicauda in the Centro Poblado La Esperanza, Amazonas department between May 2008 and March 2009. We conducted census work in an area comprising disturbed primary cloud forest interspersed with pasture lying between 3 protected areas, all of which are known to contain populations of Oreonax flavicauda. We used standardized line transect methodology to census an area of ca. 700 ha. We also recorded group size and composition. We compared the results of transect width estimation, Krebs’ method, and an ad libitum total group count. We calculated individual densities of 8.27/km2 and 9.26/km², and group densities of 0.93/km2 and 1.04/km² using Krebs’ method and transect width estimation, respectively. Average group size was 8.9, with 1–3 adult males, 1–6 adult females, and 0–6 juveniles and infants. The results from our transect surveys coincided well with our estimated total group count. Our results are similar to those from previous studies, although differences in methodologies and site-specific environmental factors make comparison difficult, and suggest that Oreonax flavicauda is able to survive in disturbed habitat when hunting pressure is low.


Conservation Density estimates Lagothrix flavicauda Line-transect methods 



We thank the editor and 4 anonymous reviewers for their comments on earlier versions of this manuscript. This work was funded by small grants from Primate Conservation Inc, Primate Society of Great Britain, Apenheul Primate Conservation Trust, Born Free Foundation, Idea Wild, International Primate Protection League, La Vallée des Singes, Restore UK and The Monkey Sanctuary Trust/Wild futures. We also wish to thank Instituto Nacional de Recursos Naturales/Direccion General de Flora y Fauna Silvestre (Autorización No. 130-2007-INRENA-IFFS-DCB; No. 122-2008-INRENA-IFFS-DCB), Mariella Leo Luna, Prof. Victor Pacheco, Prof. Anthony diFiore, Dr. Christopher Schmitt, Dr. Mark Bowler, Dr. Noel Rowe, Dr. Thomas Defler, and Dr. Angela Maldonado as well as the many field assistants for their help and advice. We owe a special thank you to all the people and authorities of the Comunidad Campesina de Yambrasbamba and the Centro Poblado La Esperanza.


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Copyright information

© Springer Science+Business Media, LLC 2011

Authors and Affiliations

  1. 1.Neotropical Primate ConservationCornwallUK
  2. 2.Durrell Institute of Conservation and EcologyUniversity of KentCanterburyUK

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