Date of Award

Fall 2018

Project Type

Thesis

Program or Major

Natural Resources

Degree Name

Master of Science

First Advisor

Rebecca J Rowe

Second Advisor

Allyson L Degrassi

Third Advisor

Russell G Congalton

Abstract

Resources, such as food and shelter, are unevenly distributed across the landscape at both macro and micro scales. Home range is one measure of space use that reflects an individual’s resource requirements (e.g., microhabitat characteristics) and competition for those resources (e.g., density dependence). This study focuses on the home range of the southern red-backed vole (Myodes gapperi), comparing field methods for estimating home range and modeling the microhabitat characteristics that define the core area of the home range. Southern red-backed voles (Myodes gapperi) are common to boreal forests, most often found in coniferous or mixed deciduous stands, and in the northeast, have an affinity for eastern hemlock (Tsuga canadensis). With eastern hemlock populations in decline due to the invasive eastern hemlock woolly adelgid (Adelges tsugae), it is unknown how M. gapperi space use will be affected.

From 2014-2017, southern red-backed voles were censused across 12 (~1 ha) grids using mark-recapture methods and for a subset of individuals radiotelemetry. Individual home range size, core area size, and core area overlap were calculated for adults using kernel density estimators from both mark recapture live trapping and radiotelemetry data. At each capture point, forest structure, ground cover, and geographic features were measured to assess influence of microhabitat on home range and core area. Density was calculated on each grid for each year of the study using the POPAN parameterization of the Jolly-Seber model.

In this thesis, Chapter One presents the effects of M. gapperi density on individual home range and core area. Differences in size and overlap are examined within and between sexes, and estimates compared between the two field techniques, mark-recapture and radiotelemetry, often used to delineate home range and core area. Density did not affect space use and female voles shared area more often with males than other females. The home range size of males was larger than that of females, however, core area was consistently about 30% of total home range. Area estimates generated under mark-recapture and radiotelemetry were similar for females, but differed for males with larger home ranges calculated using radiotelemetry. Mark-recapture methods may have underestimated male home range as a consequence of the trapping grid being smaller than male home range.

Chapter Two identifies habitat characteristics at the macro and micro scale that influence M. gapperi space use. Macrohabitat differences were evaluated between trap stations that were visited and were not visited by M. gapperi and microhabitat characteristics were modeling within female M. gapperi core areas. Myodes gapperi are found in areas with higher eastern hemlock basal area and more coarse woody debris. Within these stands, female M. gapperi select for core areas closer to water, with greater red maple basal area, deeper leaf litter, and a greater density of hemlock stems.

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