UBC Theses and Dissertations
Mammal community responses to human disturbance : insights from global camera trap surveys Chen, Cheng
In the age of the ‘Anthropocene,’ the impact of human activities on the environment is considered the major cause of the ongoing biodiversity loss. Conservation efforts to halt such loss are often hindered by limited data. As human activities continue to increase across the planet, research on how wild animals respond to them has become a priority. To better understand human impacts on wild mammals, I synthesized an extensive global camera trap dataset comprising data from > 8,600 cameras across 28 countries from four continents. I first tested the concordance between empirical observations of species occurrences from camera trap surveys and the predicted species distributions from the International Union for Conservation of Nature (IUCN) range maps for 510 medium- to large-bodied mammalian species. Across all areas, cameras detected 39% of the species that were expected to occur based on the IUCN ranges. The probability of mismatches between camera traps and IUCN range maps was significantly higher for smaller-bodied mammals and habitat specialists in the Neotropics and Indomalayan realms and in areas with shorter canopy forests. IUCN range maps for mammals are prone to overestimation and camera surveys may miss some species but provide valuable data to improve knowledge of species distribution. I next evaluated the relationships between two forms of mammalian diversity—taxonomic and functional—and three key indicators of anthropogenic pressure—human footprint, human accessibility, and protected area (PA) coverage. I found a strong positive correlation between mammalian taxonomic diversity and the proportion of a surveyed area covered by PAs at a global scale; however, no correlation was observed between diversity and human footprint or accessibility. Finally, using a subset of the global dataset, I tested the effects of anthropogenic disturbances on the abundance of functional groups of mammals in six protected tropical forest areas in South America. I found that large, strictly ground-dwelling mammal species were less abundant at sites closer to human settlements whereas carnivores capable of climbing were more abundant at these sites. Overall, this work provides insights into where and how anthropogenic disturbances affect mammalian communities globally.
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