Masters Theses

Date of Award

5-1997

Degree Type

Thesis

Degree Name

Master of Science

Major

Wildlife and Fisheries Science

Major Professor

Michael R. Pelton

Committee Members

Joe Clark, David Buehler, Ken Orvis

Abstract

Twenty Louisiana black bears (Ursus americanus luteolus) were captured 23 times on a privately-owned study area (350 km2) in the Tensas River Basin in northeast Louisiana. The area consisted of 4 major isolated bottomland hardwood fragments totaling < 35 km2, surrounded by extensive agricultural fields. Radio-telemetry, geographic information systems (GIS), and habitat sampling were used to determine corridor use, feeding ecology, and habitat relationships.

A total of 2,417 telemetry locations were obtained from 19 radio-collared bears (13 female, 6 male). Mean annual home-range estimates were 41.6 km2 and 13.2 km2 for males and females, respectively. Seasonal home ranges were largest in summer, with males having larger home ranges than females in all seasons.

Radio-collared bears were located in corridors and forested tracts more than expected in proportion to occurrence, whereas there were fewer locations than expected in agricultural fields (P < 0.001). Locations in corridors were farther from forested tracts (x̄ = 1,443 m, S.D. = 913 m) than locations in fields (x̄ = 290 m, S.D. = 292 m) (P < 0.001). Bears were radio-located in corridors most often during the summer months; of 115 corridor locations, 64 were in June and July. Bear sign along corridors indicated that most activity occurred in May and June.

I documented radio-collared bears moving from 1 forested tract to another on 47 occasions. All males (n = 6) moved to another tract other than the tract of capture, whereas only 3 of 13 females moved to another tract other than the tract of capture. Males do not seem to be affected as much as females by the level of fragmentation on the Deltic study area. Of the 33 male tract-to-tract movements, 52% were from tracts linked with a corridor, whereas, of the 14 female tract-to-tract movements, 100% were from tracts linked with a corridor.

Seasonal and annual diets of bears on the Deltic study area were determined from analysis of 249 scats. Agricultural crops (com, wheat, oats) comprised 49% of the annual diet by volume. Natural foods in the annual diet were dominated volumetrically by unknown vegetation, paw paw (Asimina triloba), and oak (Quercus spp.) mast, accounting for 12%, 11%, and 7% of the diet, respectively.

An index based on 11 habitat variables was developed to determine relative habitat quality between 4 habitat fragments. The results indicated that Blue Cat contained the best bear habitat, followed by Wade Bayou, Panther Lake, and Brownie. Two indices of bear activity between the 4 habitat fragments supported the results of the habitat index.

All radio-collared bears denned in bottomland hardwood habitat. Of the 9 radiocollard bears (8 females, 1 males) monitored the winter of 1994-1995,2 females denned in hollow trees and the remainder used ground dens. Of the 8 radio-collared bears (5 females, 3 males) monitored the winter of 1995-1996, one female denned in a hollow tree and the remaining females used ground dens. Mean litter size was 1.8 and ranged from 1 to 3 (n = 4). I documented no cub mortality.

Two mortalities of radio-collared bears occurred during the study. One subadult female was killed in a vehicle collision, and the other was a suspected vehicle collision. No instances of bear poaching have been reported on the study area, nor in the Tensas River Basin since 1991.

Prior to October 1996, there was some speculation that this bear population may be isolated. There had been no documentation of bear immigration or emigration nor of a bear crossing Interstate 20 (1-20), which bisects the Deltic bear population from the Tensas River National Wildlife Refuge (TRNWR) population. In October 1996, a subadult male bear tagged on the Deltic study area in May 1995 was captured on the TRNWR. This was the first documentation of a bear crossing 1-20 within the Tensas River Basin.

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