McFarlane, Samantha Amy

Variation in habitat quality and disturbance levels can strongly influence a species' distribution, leading to spatial variation in population density and influencing population dynamics. It is therefore critical to understand how density can lead to variability in demographic responses for effective conservation and recovery of species. My dissertation illustrates how density and spatial familial networks can be integrated together to gain a better understanding of the influence of density on population dynamics of boreal caribou. First, I created an analytical framework to assess results from empirical studies to inform spatially-explicit capture-recapture sampling design, using both simulated and empirical data from noninvasive genetic sampling of several boreal caribou populations in Alberta, Canada, which varied in range size and estimated population density. Analysis of the empirical data indicated that reduced sampling intensity had a greater impact on density estimates in smaller ranges, and the best sampling designs did not differ with estimated population density but differed between large and small population ranges. Secondly, I used parent-offspring relationships to construct familial networks of boreal caribou in Saskatchewan, Canada to inform recovery efforts. Using network measures, I assessed the contribution of individual caribou to the population with several centrality measures and then determined which measures were best suited to inform on the population demographic structure. I found substantial differences in the centrality of individuals in different local areas, highlighting the importance of analyzing familial networks at different spatial scales. The network revealed that boreal caribou in Saskatchewan form a complex, interconnected familial network. These results identified individuals presenting different fitness levels, short- and long-distance dispersing ability across the range, and can be used in support of population monitoring and recovery efforts. Finally, I used a spatial capture-recapture analytical framework with covariates to estimate spatial density of boreal woodland caribou across the Saskatchewan Boreal Plains, and then reconstructed parent-offspring relationships to create a familial network of caribou and determined whether spatial density influenced sex-specific network centrality, dispersal distance, individual reproductive success, and the pregnancy status of females. I show that caribou densitygreatly varied across the landscape and was primarily affected by landscape composition and fragmentation, and density had sex-specific influences on dispersal distance, reproductive success, and network centrality. The high density areas reflected good-quality caribou habitat, and the decreased dispersal rates and female reproductive output suggest that these remnant patches of habitat may be influencing demographic responses of caribou.

Author Keywords: boreal caribou, density, familial networks, population dynamics, rangifer tarandus caribou, spatial capture-recapture