Date of Award

12-2016

Level of Access

Campus-Only Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Wildlife Ecology and Wildlife Conservation

Advisor

Cynthia Loftin

Second Committee Member

Aram Calhoun

Third Committee Member

Brian McGill

Additional Committee Members

Frank Drummond

Daniel Harrison

Abstract

Montane amphibians face many challenges. For example, amphibians are among the most climate change vulnerable taxa; high elevation populations are thought to be less resilient than lowland populations; and forested wetlands, a primary breeding habitat for many montane species, have sustained the greatest loss in area of all wetland types. Broadly, the aim of my dissertation was to evaluate the habitat ecology of pool-breeding amphibians during all annual life history periods (i.e., breeding, post-breeding, hibernal) in the Mountains of the Dawn. This research was conducted during 2011–2014 in Maine’s Upper Montane/Alpine Zone and Quebec/New England Boundary Mountains ecoregions.

Breeding period. I evaluated the relative importance of breeding and landscape features to spotted salamander (Ambystoma maculatum) and wood frog (Lithobates sylvaticus) wetland occupancy. Occupancy by both species was influenced solely by breeding scale habitat features. Spotted salamander occupancy probabilities increased with beaver (Castor canadensis) presence, and wood frog probabilities increased with site area and percent shallows. These results suggest pool-breeding amphibian conservation in montane Maine include measures to maintain beaver populations and large wetlands with proportionally large areas of shallows ≤ 1 m deep.

Post-breeding period. I evaluated wood frog habitat selection and movement patterns during spring migration and the post-breeding period and described the spatio-temporal variability of used habitats. Telemetered frogs spent the greatest percentage of each field season in hibernacula, followed by post-breeding, migration, then breeding habitats. During spring migration, frogs exhibited different movement patterns (e.g., turn angles), selected different habitat features, and selected habitat features less consistently than during the post-breeding period. These results indicate the migration and post-breeding periods are ecologically distinct. Failing to discriminate among annual life history periods may obscure true ecological relationships.

Hibernal period. I evaluated wood frog thermal ecology within hibernacula and hibernal habitat selection. Hibernaculum temperature and relative humidity was significantly different and less variable than leaf litter, ambient air, and random location microclimate. Frogs selected for decreased canopy cover and increased leaf litter depth and microhabitat structure (i.e., logs, stumps). These habitat features likely insulate hibernating frogs from extreme and variable air temperatures and, therefore, may be critical to the species’ acclimatization to altered winter conditions (e.g., reduced snowpack).

Cumulatively, my results indicate pool-breeding amphibians are place-based species with flexible ecologies that vary spatially. Therefore, the efficacy of amphibian conservation may be improved by considering how context (i.e., environment characteristics) shapes and defines these species’ ecologies.

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