Date of Award

2021

Degree Type

Thesis

Degree Name

Master of Science in Biological and Environmental Sciences (MSBES)

Department

Biological Sciences

First Advisor

Brian Gerber

Abstract

Tropical biodiversity is threatened globally by anthropogenic disturbances, particularly forest degradation and overhunting. Where large mammals have been extirpated, smaller-bodied “mesomammals” may play an important ecological role (e.g., as seed-dispersers). However, mesomammals are routinely understudied as they tend to be rare, cryptic, and nocturnal. Tropical tree-dwelling (arboreal and semi-arboreal) mesomammals are especially vulnerable to forest conversions, particularly when reliant on old growth forest structures. Understanding species- and community-level responses of terrestrial and arboreal mesomammals to changes in forest structure and human activity is crucial for informing management decisions in protected areas where resources are limited. We deployed 20 arboreal and 75 terrestrial camera traps throughout Nam Cat Tien National Park, southern Vietnam. The study objectives to the first chapter were to 1) identify long-term changes in terrestrial mesomammal richness and 2) evaluate the effects of forest structure and anthropogenic disturbance on an 18-species mesomammal community using community occupancy models. The objectives of the second chapter were to 1) evaluate the utility of arboreal camera traps for surveying nine arboreal and four semi-arboreal tropical mesomammals, 2) model the effects of forest structure and anthropogenic disturbance on detection and occurrence of arboreal mesomammals using generalized linear mixed models and single-season occupancy models, and 3) estimate arboreality of semi-arboreal species using multi-scale occupancy models. We found that terrestrial mesomammal site occupancy was driven largely by the interaction between distance to seasonally inundated grassland and absolute forest cover (basal area per hectare). We found no negative effects of anthropogenic factors at the community-level.

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