Date of Award
Master of Science (MS)
Accurate and precise estimates of abundance are crucial for wildlife management. Wildlife agencies spend large amounts of time and money to obtain estimated abundance. The Kansas Department of Wildlife Parks and Tourism (KDWPT) has conducted strip transect (ST) counts biannually since 1963 to estimate pronghorn (Antilocapra americana) abundance in Kansas. However, the accuracy and reliability of results are questionable. Distance sampling (DS) is a method used to estimate abundance of a biological population. All perpendicular distances of objects to the transect line are recorded; however, there is no designated strip width and no assumption that all objects are detected. I conducted DS surveys and ST surveys biannually between the summer of 2012 and the winter of 2014 in western Kansas. The objectives of the study were to: (1) compare DS results to ST results from winter and summer, (2) compare DS results from winter and summer, (3) evaluate the time and cost needed to complete both methods, and (4) evaluate the feasibility of reducing to 1 DS survey per year. Results from the DS and ST methods in the winter provided similar estimated abundance. Timing of flights had a substantial effect on cluster size, fawn:doe ratios, and buck:doe ratios. Summer DS surveys yielded larger sample sizes and more precise estimates than winter DS surveys. Cluster size, side (of the plane pronghorn were detected), distance to road, and habitat were the most influential covariates on detection probability. Detection probability was higher in cropland than in rangeland. Because DS results indicated that pronghorn avoided within 200 to 300 m of roads, I suggest that the DS transect placement be changed to 1 of 3 options: (1) transects angled to roads, (2) randomly placed north-south oriented transects, or (3) north-south oriented transects placed 800 m from roads. I suggest that the KDWPT conduct 1 DS flight per year, in the summer, during a small temporal window. Doing so would save the KDWPT time, money, and avoid risk from unnecessary flight time, while still providing reliable population estimates.
Copyright 2014 Jared H. Oyster
Oyster, Jared H., "Distance Sampling as a Technique to Monitor Pronghorn in Kansas" (2014). Master's Theses. 72.