Masters Theses

Date of Award

12-2002

Degree Type

Thesis

Degree Name

Master of Science

Major

Wildlife and Fisheries Science

Major Professor

Frank van Manen

Committee Members

Joe Clark, Mary Sue Younger

Abstract

Acorn Production and Black Bear Abundance

I investigated the relationship between black bear population abundance and acorn production based on two different mast indices (Whitehead index and a mast regression index) in the Great Smoky Mountains National Park. I used hard mast data on northern red oak trees and white oak trees obtained from the National Park Service annual mast surveys (1979-2000). Estimates of bear population abundance were obtained from a mark-recapture study in the northwestern quadrant of Great Smoky Mountains National Park, and were divided into two time periods: 1981-1999, and 1990- 2000. Black bear population abundance was calculated using the Jolly-Seber model.

Mast data and black bear population estimates used in this study were time-series, so relationships were examined using autoregressions. 1 explored all possible variable combinations of northern red oak and white oak using lag times in the data for up to 3 years. For the period 1981-1999, the best model for both mast production methods included the white oak mast index from the current year. The mast regression index best predicted black bear population estimates for this time period (R2 = 0.53). Autoregressions using population estimates from 1990-2000 indicated that white oak mast from 2 years before was an important variable. The Whitehead index best predicted black bear population estimates for this time period (R2 = 0.49).

My study suggests that white oak mast may correspond more to population dynamics of black bears than northern red oak. White oak from previous years occurred more often than red oak in the more significant regression models. White oak mast from the current year also consistently showed significance; because population estimates for a given year were derived before the mast surveys were conducted; this variable likely is a surrogate for soft mast production. Northern red oak from the previous year also was an important variable.

For the time period 1981-1999 the mast regression index predicted black bear population estimates better than the Whitehead index. For the time period 1990-2000 the Whitehead index better predicted the black bear population estimates than the mast regression index. Population estimates for the period 1990-2000 may have been more accurate, which may have caused this difference in results compared with the 1981-1999 period. Because bears can easily switch to alternate food sources, problems may arise in detecting relationships between the black bear population and only one food source. In this study much of the variation cannot be explained, and future studies including other species of oaks along with other food sources may need to be examined. Information from this study may help wildlife managers better anticipate how the black bear population in Great Smoky Mountains National Park will respond to certain changes in mast production.

Survival of Female Black Bears From 1999 through 2001, adult female black bears trapped during the summer mark-recapture study conducted in the northwestern quadrant of Great Smoky Mountains National Park were fitted with radio collars. From October 1999 through April 2001, I located 32 radio-collared female bears once every month. To estimate survival, I used a modified Kaplan-Meier staggered entry procedure, which corrects for the number of animals at risk (number of animals detected) due to uncertain relocation of individuals (Bunck et al. 1995). During the study 6 bears were censored, and signals of 9 radio collars switched to mortality mode; of these 3 could not be retrieved and 6 were prematurely dropped. No mortalities were observed throughout the study, and the survival rate of female black bears was 1.0.

The results of my study suggest that survival among adult female bears within a protected area is high. Expanding the use of aerial telemetry during future monitoring may reduce the number of censored bears and improve the ability to detect mortalities. Due to the longevity of bears, longer-term research will be needed to better document trends in female black bear survival in Great Smoky Mountains National Park.

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