An Evaluation of Radioactive Feces-Tagging as a Technique for Determining Population Densities of the Black Bear (Ursus americanus) in the Great Smoky Mountains National Park
Date of Award
Master of Science
Wildlife and Fisheries Science
Michael R. Pelton
R. L. Murphree, Dan J. Nelson, James L. Byford
This study was conducted on the Tennessee side of the Great Smoky Mountains National Park west of highway U.S. 441. The major objectives were to evaluate selected radioisotopes as possible scat (feces) tags and to determine estimates of the black bear population using data collected by the technique of marking scats with a radioactive tag and to evaluate the reliability of the population estimates.
In June of 1972 two confined bears were injected with four selected radioisotopes; 65Zn and 54Mn proved suitable as tags but 109Cd and 144Ce were unsatisfactory.
From June through September of 1972, 30 bears were ear tagged of which 28 were injected with radioisotopes; 189 scats were collected from the study area, 35 of which were radioactively tagged. Using the Schnabel formula, the population was estimated to be 102 animals. For the same period 259 observations of black bears were made with 130 of these animals being tagged; a population estimate using these data was 42 animals.
From June through September 1973, 35 bears were ear tagged of which 32 were injected with radioactive materials; 240 scats were collected with 41 being radioactively tagged. Bear observations for 1973 totaled 117 with 48 of the animals being ear tagged. Population estimates using the two sets of data were 132 and 54 animals, respectively.
The density of black bears for the area censused was estimated to be 1 bear per 1.06 square miles (680 acres). Two smaller areas within the study area had estimated densities of 1 bear per 0.42 square miles (275) (40 bears on 17 square miles) and 1 bear per 0.54 square miles (342) (28 bears on 15 square miles).
The estimates based on data from radioactively tagged scats were believed to be more accurate than those from mark-observation data due to a removal of biases caused by unequal vulnerability of individual bears, loss of tags, and failure to recognize tags. The estimate of 1973 using radioactively tagged scats was believed to be the most accurate due to a more random distribution of marked animals within the study area. Other possible applications of the technique include population mixing, dispersal, and mortality.
Marcum, Larry Calvin, "An Evaluation of Radioactive Feces-Tagging as a Technique for Determining Population Densities of the Black Bear (Ursus americanus) in the Great Smoky Mountains National Park. " Master's Thesis, University of Tennessee, 1974.