Characteristics and Use of Sleeping Sites in Aotus (Cebidae: Primates) in the Amazon Lowlands of Peru

.ROLANDO AQUINO AND FILOMENO ENCARNAC16N IVITA, R 0. Box 575, Iquitos, Peru

In the Amazon lowlands of Peru, Aotus nancymai and A. vociferans were observed to use four different types of sleeping sites: 1) holes in the trunks and branches of dry or senescent trees; 2) concavities in polyaxial branching nodes of trees protected by dense entanglements of creepers, climbing plants, vines, and masses of diverse epiphytes; 3) complex sites among masses of epiphytes, climbers, and vines; and 4) simple sites among thickets and dense foliage. Each type is described. There was competition and sharing of sleeping holes between Aotus and other nocturnal arboreal mammals.

Key words: Aotus nancymai, Aotus vociferans, forest strata.

Received January 21, 1986; revision accepted July 15, 1986. Address reprint requests to Rolando Aquino and/or Filomeno Encarnación, IVITA, P.O. Box 575, Iquitos, Perú. © 1986 Alan R. Liss, Inc.
 

INTRODUCTION

All neotropical nonhuman primates are diurnal with the exception of Aotus , which is nocturnal. Prior to 1982, all studies of Aotus in natural areas referred to Aotus trivirgatus as the only species occurring in South America. Hershkovitz [1983] recognized the existence of nine species of the genus Aotus . With the description of Aotus hershkovitzi by RamirezCerquera [1983], the number of species of Aotus has been increased to ten.

Napier and Napier [1967] and Wright [1978, 1981] described the daytime sleeping sites of Aotus as tree holes, entanglements of climbers and vines, and thickets of bamboos and vines. Wright based her observations on a family group living in a hillside forest along the Pichis River near Puerto Bermudez, Department of Pasco, Peru. Hershkovitz [1983] described the daytime sleeping sites of Aotus nancymai as lacking any sign of intentional construction in trees or in entanglements of climbers and vines supported by the branches of large trees. CoimbraFilho [1977], in a study of the ecology of Leontopithecus rosalia, described the use of tree holes as refuge from predators and for resting or nighttime sleep. Aotus and Leontopithecus are the only neotropical primates that sleep in holes in the trunks of trees.

We located and examined the sleeping sites of 77 family groups of Aotus . Following Hershkovitz [1983], 42 groups were Aotus nancymai and 35 were A. vociferans, including a new karyotype among the "grey neck species group" of Hershkovitz [Ma et al, 19851'. Family groups of Aotus nancymai were located in the forest along the Tahuayo River. Family groups of A. vociferans were studied along the Nanay and Napo Rivers. These study sites were in the Department of Loreto. Our longterm observations (19811983) have shown that Aotus sleep from between 05000550 hours to 18001835 hours (local time) while hidden in sleeping sites located in holes or concavities in trees or among entanglements of climbers, vines, epiphytes, and other dense foliage. Other arboreal and nocturnal mammals such as Potos flavus, Bassaricyon gabbi, Isothrix villosa, Coendu bicolor, and bats use sleeping sites similar to, or the same as those of Aotus , often with indirect competition or timesharing.