Date of Award
University Scholars Director
Dr. Jeff Keuss
Ecology, Blakely Island, Holodiscus discolor, browsing
I estimated deer density and population size on Blakely Island, WA, using the fecal standing crop (FSC) method described by Martin et al. (2011). I compared the FSC method with a well established and broadly applicable estimation method, distance sampling. Additionally, architecture of a commonly browsed shrub, Ocean Spray (Holodiscus discolor), was measured as an indicator of browsing pressure. Fecal standing crop was estimated by counting pellet groups along 26, 100 x 2m line transects. Deer density was estimated using these data and the equation derived by Martin et al. (2011). Distance sampling consisted of recording perpendicular distance from transect line to deer, along 16 saw-toothed transects placed across Blakely Island. An average architecture value (ratio of plant diameter at 1 and 2m) of 0.223 indicated a high browsing pressure on the island, suggesting high deer density. Deer density based on FSC method was 1.72 (95% CI: 1.21 – 2.23) deer ha-1, whereas the concurrent deer density based on distance sampling was 0.23 (95% CI: 0.138 – 0.375) deer ha-1. Previous studies on Blakely using the latter method have shown deer density at ≈0.3 deer ha-1. As the FSC density estimation was much greater than that of distance sampling, and because it did not compare to other high-density island populations of deer, I concluded that this newer technique may not be comparable to well established methods. Further experimentation is necessary to parse out the possible confounding factors associated with the FSC technique.
Brenneman, Jubilee D., "Comparing Population Density Estimation Techniques for Columbia Black-tailed Deer (Odocoileus Hemionus Columbianus): Fecal Standing Crop and Distance Sampling Methods" (2014). Honors Projects. 5.