First Advisor

Amy Schreier

College

Regis College

Degree Name

MS Environmental Biology

Document Type

Thesis - Open Access

Abstract

Habitat loss due to deforestation is a primary threat to global biodiversity. Clearing tropical rainforests for agriculture leads to forest fragmentation. Forest fragments contain fewer large trees and provide lower food availability for primates compared to continuous forests. Mantled howler monkeys inhabit the increasingly fragmented rainforests of Central and South America and may need to alter their activity and spatial cohesion to mitigate competition and preserve energy in fragments where there is lower quality food. We compared howler monkey activity and spatial cohesion across a small forest fragment (La Suerte Biological Research Station, LSBRS) and a large, continuous forest (La Selva Research Station) in northeastern Costa Rica. We predicted that monkeys at LSBRS would rest more, feed more, travel less, and be less spatially cohesive compared to La Selva to contend with fewer resources and higher competition in the small fragment. Using instantaneous scan sampling at two-minute intervals during 30-minute focal samples, we recorded activity and counted the number of individuals within 5 meters of the focal animal. The probabilities of observing each behavior differed significantly across sites. As predicted, monkeys at LSBRS fed more than those at La Selva, but contrary to our predictions, they rested less and traveled more. The mean number of individuals within 5 m was significantly lower at LSBRS compared to La Selva. The ability to modify their activity and spatial cohesion in response to fragmented forests provides insight into how primates can contend with fewer resources and higher competition in changing ecosystems worldwide.

Date of Award

Spring 2024

Location (Creation)

Denver, Colo.

Rights Statement

All content in this Collection is owned by and subject to the exclusive control of Regis University and the authors of the materials. It is available only for research purposes and may not be used in violation of copyright laws or for unlawful purposes. The materials may not be downloaded in whole or in part without permission of the copyright holder or as otherwise authorized in the “fair use” standards of the U.S. copyright laws and regulations.

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