Contributions to Zoology, 80 (4) – 2011Sam Shanee; Noga Shanee: Activity budget and behavioural patterns of free-ranging yellow-tailed woolly monkeys Oreonax flavicauda (Mammalia: Primates), at La Esperanza, northeastern Peru

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Material and methods

Study site

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The Comunidad Campesina de Yambrasbamba study area lies on the eastern slopes of the Andes in Northeastern Peru. The area, known locally as Peroles (S 05°39’46”, W 77°54’32”), encompasses approximately 1000 hectares of disturbed primary forest and regenerating secondary forest interspersed with pasture. The study site is bounded to the south, east and west by pasture and agricultural lands and to the north it is contiguous with extensive forest reaching to the Río Maranon (approximately 100 km). The site was chosen because of its location in a natural forest corridor between four protected areas where the species’ presence has been recorded: Santuario Nacional Cordillera Colan, Bosque de Proteccion Alto Mayo, Zona Reservada Rio Nieva and the Area de Conservacion Privada Abra Patricia-Alta Nieva (Fig. 1). The area is located about 5 km north of the village of La Esperanza, and lies between 1800 and 2400 m.a.s.l. Average monthly rainfall is approximately 1500 mm with a dry season from August to December. Average temperature for the area is 14°C (± 5.7). Humidity is high year round.

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Fig. 1. Location of study site, showing outlying protected areas.

The terrain is very rugged with high ridges and deep valleys, while the habitat in the area is characterised by Ficus spp. dominated primary pre-montane and montane cloud forest with an average canopy height of 15-25 m, including occasional emergent trees of up to 35 meters and a thick mid- and under-story.

Survey design

Data were collected on three groups of O. flavicauda using focal animal sampling (Altmann, 1974). We alternated between two field camps, each camp with one home group and one intermediate group with territory overlapping the two camps. All the groups in the study area were at least partially habituated to the presence of humans through contact with our researchers during previous field work. Habituation to the presence of humans had also occurred over previous years when small scale commercial logging took place; also the area is interspersed with pastures and plantations with farmers regularly passing through the forest on the way to their lands. Hunting had not occurred in the area for at least 5 years prior to the start of field work. Group follows were carried out by two pairs of trained observers each comprising one researcher and one local field assistant. We selected focal animals to try and evenly sample across age/sex classes. Focal animals were observed until they were lost from sight for a continuous period of over 10 minutes or could not be located again. Animals were not recognized individually. Field work took place between 0530 and 1900 hours. Follows started when a group was located and finished at sunset when the whole group became inactive after reaching a nesting site or when the group was lost or could not be followed because of inclement weather or topographical constraints. Data collectionData collection lasted 15 months between October 2009 and July 2010 and between September 2010 and February 2011. We made five day field trips twice monthly for the duration of the study and recorded point samples on a focal individual every two minutes on a standardized record sheet. We defined age/sex classes as follows: Adult male, Adult female, Adult female with dependant infant, Juvenile male; Juvenile female and Undefined juvenile (Table 1).

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Table 1. Age/sex class definitions and sampling effort per class.

Eleven behavioural categories were chosen and defined: Feeding, Resting, Travelling, Vocalizing, Auto-Grooming, Allo-Grooming, Aggression, Sexual, Play, Watching observer, and Out of sight (Table 2).

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Table 2. Behavioural categories and definitions.