Date of Award

Spring 5-2025

Document Type

Thesis

Department

Environmental Science

First Advisor

Eduardo Fernandez-Duque

Second Advisor

Indy Burke

Abstract

Azara’s owl monkeys (Aotus azarae) are small, pair-living, socially monogamous primates that inhabit the Chaco Forest of South America. Their activity and life history patterns have been particularly well studied, however, their movement ecology and ranging patterns within their home ranges remains largely unknown. Herein I descriptively analyze these patterns with respect to time, space, ambient environment, and physical environment using spatial information on five owl monkey groups that were followed over the course of a year between 1998 and 1999 at a multi-decade-operating field site near Formosa, Argentina. Analysis of distance and speed moved during different diel periods confirmed their cathemeral activity pattern, with a crepuscular bias during dawn and dusk. They moved the most distance at dawn during winter and spring, fastest at dawn and dusk in spring, and were most active at night during spring and summer. However, they still moved the most and the fastest overall during summer. Movement increased with ambient temperature and the amount of moonlight at night when there was less thermoregulatory stress and when easier visual perception, but not in relation to the river that surrounds the field site, near to which it was hypothesized that fruit trees would provide more consistent sources of food. Groups spent the most time in the core of their home ranges, particularly during the day when they were most likely sleeping, but moved the furthest and fastest in the periphery at dawn where they were possibly patrolling for other groups and foraging during seasons of food scarcity such as winter. Together, these insights reveal the complex and dynamic nature of the behavioral ecology of Azara’s owl monkeys and how they navigate through their environment.

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