SPATIAL ECOLOGY OF GRIZZLY BEARS IN NORTHWESTERN MONTANA: DISSERTATION PROPOSAL

We will use genetic information to assess the influence of habitat and human influences on abundance, dispersal, and gene flow of grizzly bears (Ursus arctos) in the Northern Continental Divide Ecosystem (NCDE). We ask four questions:

1. Which landscape characteristics influence abundance of grizzly bears in the NCDE? Over 1500 genetic captures of 545 grizzly bears collected in 2004 across the ~ 8 million acre Northern Continental Divide Ecosystem were formatted as a spatial mark-recapture data set to estimate local bear abundance. We will use a hierarchical Bayesian analysis incorporating 1) detection probabilities, 2) multiple sampling methods, and 3) spatial autocorrelation to identify the landscape variables most important to abundance of male and female grizzly bears.

2. What landscape and population characteristics promote dispersal in a natural population of grizzly bears? Natal dispersal comprises three key steps: 1) emigration, 2) movement through the landscape, and 3) immigration. We will identify parent-offspring pairs to look at the three stages of dispersal directly.

3. Can we quantify resistance of landscape characteristics to gene flow? Gene flow reflects a process occurring over several generations and results only when individuals disperse and reproduce. We will use a Bayesian approach with circuit theory to measure the resistance of landscape characteristics using genetic distance as a response variable.

4. What landscape or population characteristics describe areas where dispersal occurs but gene flow does not result? Comparison of our results can guide management for genetic as well as demographic connectivity.