• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 1
  • Tagged with
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Influence of gypsy moth induced oak mortality on a black bear population

Schrage, Michael W. 10 January 2009 (has links)
During June 1990 - November 1993 I measured the responses of black bears (Ursus americanus) in Shenandoah National Park (SNP), Virginia to gypsy moth (Lymantria dispar) induced oak (Quercus spp.) mortality. Oak species composed >50% of the forest canopy of SNP, and oak mortality rates ranged from 1- ≥48%. I compared black bear population dynamics, food habits, movements and habitat use to preinfestation data collected in SNP from 1982 - 1985. Scat analysis indicated that the current diet of SNP’s black bear population includes proportionally more soft mast in the fall and more soft mast and ants (Formicidae spp., P<0.0001) in the summer than did the preinfestation diet. Fewer acorns (Quercus spp. mast, P=0.03) and squawroot (Conopholis americana, P=0.01) were consumed in the fall and summer respectively. No decline in the physical condition of adult females (P=0.91), subadult males (P=0.34) or subadult females (P=0.94) was evident. Adult male physical condition declined (P=0.03) for unknown reasons. The mean age of neither female (P=0.99) nor male bears (P=0.54) was different from preinfestation data. Mean litter size - 2.25 cubs - did not differ (P=0.49) froma preinfestation mean of 2.0 cubs. Survival of radio-collared female bears was 100%, indicating that the female survival rate has not declined from a high preinfestation survival rate. Minimum cub survival rate to 1 year was 64.7%. Fall and annual home ranges of female bears were smaller (P=0.001 and P=0.002, respectively) than during preinfestation years. Use of forest cover types differed from availability during the summer (P<0.01), early fall (P<0.0001) and late fall (P<0.001) and when compared to preinfestation data. Use of stands with different levels of oak mortality was not different from availability during the summer (P=0.1) but was different during the early fall (P<0.005) and late fall (P<0.001). / Master of Science

Page generated in 0.0278 seconds