Date

Spring 2025

Document Type

Master's Thesis (Open Access)

Degree Name

Master of Science (M.S.)

Department

Applied Environmental Science

Abstract

Hoary bats and western red bats are foliage-roosting species which may be sensitive to habitat loss due to urban expansion. Habitat use by bats has mostly been studied during summer periods, but habitat use during migratory and winter periods can inform conservation strategies for these sensitive species. We aimed to determine habitat use for foraging activity across an urban-natural habitat gradient for hoary and western red bats during fall and spring migration, winter, and to determine if there is seasonal sexual differentiation in habitat use. We captured bats using mist nets at urban and natural habitats and compared sex ratios. We used passive acoustic bat detectors to assess activity for foraging across multiple urban-natural gradients by recording echolocation activity and feeding buzzes. We constructed models based on temporal and landcover parameters at variable spatial scales within a Bayesian hierarchical framework to assess whether urbanization affects habitat use for foraging. We used spatial scales from the best supported model to create a map of high, medium, and low suitability for foraging within the study area. We found that more hoary bats and western red bats were captured in natural habitats compared to urban habitats, and males were more abundant than females. We found there was strong evidence that hoary bats and western red bats will forage in shrub/ grassland habitat at small scales (0- 0.5 km radius) surrounded by substantial forested areas (radius of 1.5 to 3 km or more). These findings provide support for the conservation of larger areas of natural habitat and may reflect species' sensitivities to human-impacted environments.

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