Endangered Apes—Can Their Behaviors Be Used to Index Fear and Disturbance in Anthropogenic Landscapes?

Melissa A. Reisland,Nicholas Malone,Joanna E. Lambert

doi:10.3390/d13120660

Melissa A. Reisland, Nicholas Malone + Show 1 more

Open Access

https://doi.org/10.3390/d13120660

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Journal: Diversity	Publication Date: Dec 11, 2021
Citations: 1	License type: CC BY 4.0

Affiliation: University of Colorado Boulder, University of Auckland

Abstract

Behaviors exhibited by prey species towards predators (including humans) can reduce feeding time and increase time spent in vigilance, thereby impacting animal condition and ultimately limit populations, even when actual mortality from predation is low. Here, we test whether behavioral profiles in an endangered ape, Javan gibbons (Hylobates moloch), correspond to varying degrees of human disturbance in a human-impacted sacred forest, Cagar Alam Leuweung Sancang, West Java. Data were collected August 2010–July 2011. Although all groups reacted differently to human presence, overall, gibbons responded by reducing time spent on conspicuous behavior (e.g., vocalizing, feeding, traveling, and social interactions) as the number of humans in the area increased or distance to the nearest human decreased. In addition, gibbon responses to encountering humans were also more like their responses to encountering potential predators than they were to encountering monkeys or other gibbons. These results support the hypothesis that as human presence and encounter rates increase, gibbons alter their behavior in ways consistent with anti-predator behaviors. Assessing how this endangered species responds to human presence is a vital part of their ultimate conservation.

Highlights

We evaluated Javan gibbons’ behavioral responses to humans in Cagar Alam Leuweung Sancang (CALS) nature reserve in West Java as a proxy to predict the long-term survival of one population of this endangered species
In this research we hypothesized that Javan gibbons would respond to humans in a manner consistent with their behavioral responses to predators
We predicted that gibbons would increase time engaged in inconspicuous behaviors and decrease time engaged in conspicuous behaviors as either the number of humans increased (Prediction I)

Summary

Introduction

Low-impact human-wildlife interactions such as wildlife viewing impact animals in many ways, resulting in changes to behavior (e.g., Rangifer tarandus [1]; Rhinoceros unicornis [2]; Ursa actos [3]), habitat use [4,5]), physiology (e.g., Opisthocomus hoazin [6]), community interactions (e.g., avian scavengers [7]), and population demographics Behavioral shifts in response to human presence are consistent with responses to predation, even in the absence of hunting or trapping [9,10,11,12,13,14,15]. Modified behavior can include differences in microhabitat use (e.g., tree canopy strata), suppressed vocalization, and reduced feeding, traveling, and sociality (e.g., Alouatta pigra [16,17]; Callithrix pygmaea [18]; Gorilla gorilla gorilla, [19]; Hylobates lar and Presbytis melalophos [20,21])

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