Our data on tree species of A. vociferans differ from those of AQUINO and ENCARNACIÓN (1986), who reported that the most frequently used sleeping sites for A. nancymae (A. nancymai) and A. vociferans were Eschweilera sp. (40.207o), M. acaciifolium (12.007o), Campsiandra laurifolia (10.801o), and C spruceanum (9.001o).
Sleeping
sites formed in holes and situated in trunks and branches of dry senescent and
mature trees were classified as Type A. The access route in Type A sleeping
sites was by thin trunks and branches of neighboring trees, climbers, and vines.
This vegetation structure provided optimal conditions of shelter and security
from predators (AQUINO & ENCARNACIÓN, 1986). Access holes in some
cases were exposed, and in other cases were partially or almost totally
protected by vines and hemiepiphytes. AQUINO and ENCARNACIÓN (1986) state
that A. vociferans exclusively uses sleeping sites with protected Type
A holes. However, in the Nanay river area, we observed a group of three animals
on a sheath of a M. flexuosa palm tree in the upper light concavity of
this tree (Fig. 3). According to AQUINO and ENCARNACIÓN (1986), this
sleeping site classifies as Type C site that is normally used exclusively by
A. nancymae in inundated forest. However, the use by A. vociferans
of Type C site in this study suggests that A. vociferans use of Type
C sleeping sites is a behavioral adaptation. Forest degradation from intense
selective logging, agricultural activity, and light hunting pressure of Aotus
sp. may contribute to the reasons why A. vociferans use Type C sleeping
sites. The future existence of wild Aotus populations, and other forest
fauna and flora, requires alternative plans of natural resource management with
the participation of communities bordering Aotus habitats.
Fig. 3. Sleeping site in the small concavity of foliar she the of Mauritia flexuosa.
From the five forms of sleeping sites for A. vociferans, recorded by AQUINO and ENCARNACIÓN (1986), the sub-axial (Ac) and lateral (Ae) forms were most frequent, 46.6 and 31.1% respectively. We found differences between the river basins studied with regard to the presence or absence of certain forms of sleeping sites. In the Nanay forests, we did not find the apical position with reiterations (Ab) or sub-apical position (Ad) forms, while in the Napo river forests, all of the five forms were present (Fig. 4). In the Napo river forests, there is a greater diversity of arboreal floristic composition. This diverse floristic composition offers an abundance of climbers, vines epiphytes, and hemiepiphytes of ombrophyls on the emergent trees. This vegetation protects the animals from adverse weather conditions, direct sunlight exposure, and predators.
Cohabitations and competitive interactions using sleeping sites between Aotus and other mammals occur with some frequency. In this report we did not record direct competition as AQUINO and ENCARNACIÓN (1986) described. These investigators stated that competition occurs when the sleeping site cavity is small and shallow, and has only one access orifice. In contrast, cohabitation occurs in sleeping sites formed by wide and deep cavities with more than two access orifices, and surrounded by hemiepiphytes and hemiparasites that form steps or perches available for the animals. In our observations cohabitation between A. vociferans and other mammals occurred with more frequency than competitive interactions due to the greater availability of holes in trees with sufficiently large internal cavities in their trunks or with branches showing favorable diurnal habitats.
The results of our study describe the joint utilization of a sleeping tree between night monkeys and other nocturnal mammals (cooccupation). To our knowledge, this is the first documented report of cooccupation within Aotus sp.
Fig. 4. Frequence and use of the forms of the sleeping sites. Aa: Apical position; Ab: apical position with reiterations; Ac: sub-axial position; Ad: sub-apical position; Ae: lateral position (AQUINO & ENCARNACIÓN, 1986).
Acknowledgements. Our special thanks to the guides and field workers, Mr. GILBERTO ASIPALI, MILTON AHUANARI, and DESIDERIO MARICHI. We are thankful to Prof. RAMON CORDOVA for drawing the sleeping sites of nocturnal mammals and Miss NELLY TANCHIVA for typing the manuscript. Also we wish to thank Dr. RICHARD E. BODMER the University of Florida, and the Wildlife Group of the Amazon Conservation Fund (WACF), and Nicole Gottdenker for their valuable observations and suggestions on the manuscript, and Eng. RODOLFO VASQUEZ of Peruvian Flora Project, for the identification of botanical samples. This work was financed by the Peruvian Primatological Project "Manuel Moro Sommo" (written agreement AMRO 3171, Peru between OPS/OMS and Peruvian Government).
