Date of Award

2021

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Natural Resources

First Advisor

Therese Donovan

Second Advisor

James Murdoch

Abstract

The moose (Alces alces) population has been declining across the northeastern US largely due to the impacts of winter ticks (Dermacentor albipictus). In epizootic years, an individual moose can host a staggering number of ticks (> 60,000), affecting both survival and reproduction. Habitat management may be used to improve the status of the moose population and health of individuals, but this requires knowledge of key habitat types used by moose and their spatial distribution. We investigated 1) habitat use by moose and 2) the fitness consequences of habitat selection during two critical winter tick life stages in northeastern Vermont. To assess habitat use, we combined more than 41,000 moose locations collected from radio-collared individuals (n = 74), recent land cover data, and high resolution, three-dimensional lidar data to develop Resource Utilization Functions that linked home range use to habitat characteristics by age, season, and sex. In general, the home ranges of female moose had proportionally more regenerative forest and canopy structure, while male home ranges consisted of mixed forests at higher elevations. Winter ticks tend to be fairly immobile throughout all life stages, and therefore their distribution patterns at any given time are shaped by the occurrence of moose across the landscape during the peak of two critical time periods: fall questing (when ticks latch onto a moose) and spring drop-off (when engorged female ticks detach from moose). We used a dynamic occupancy modeling framework to estimate habitat selection of female moose (n = 74) during these periods. Further, we investigated if habitat selection decisions made by adult females during the fall questing period influenced the survival of their offspring through the winter. Adult females whose offspring perished selected habitats during the questing period that were characterized by higher proportions of young mixed forests at higher elevations. In contrast, adult females whose offspring survived selected areas characterized by young deciduous habitats and higher proportions of mature evergreens forests and wetlands at lower elevations. The resulting maps of habitat use and resource selection define “hotspots” that are likely encouraging the deleterious effects of the tick-moose cycle. These hotspots presumably reflect areas with the highest moose and winter tick densities, which may be targeted for future management actions such as hunter harvest to reduce moose density and habitat manipulation or application of experimental treatments (e.g., fungus-based biopesticides) to reduce tick density. This study provides new information and tools that may help managers disrupt the tick-moose cycle and promote heathier and more persistent populations across the region.

Language

en

Number of Pages

100 p.

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