Masters Theses

Date of Award

12-1999

Degree Type

Thesis

Degree Name

Master of Science

Major

Wildlife and Fisheries Science

Major Professor

Michael R. Pelton

Committee Members

Joseph Clark, Frank van Manen

Abstract

Forested lands in the Tensas River Basin have been reduced substantially. The Louisiana black bear (Ursus americanus luteolus), a threatened subspecies, occurs on some of the remaining bottomland forests, including several fragmented forested tracts in northeast Louisiana. Population estimates and an understanding of population dynamics are essential to manage this subspecies.

I investigated population and spatial ecology of black bears on small tracts of fragmented bottomland hardwood forest in northeast Louisiana from June 1997 to December 1998. The study area was privately owned by Deltic Farm and Timber Company and managed for agricultural and forest products.

I estimated population size using capture-resight and capture-recapture models, both within and across years. I used closed and open population models and incorporated several capture techniques to insure a robust design. I recorded 40 captures of 24 individual bears from 213 trap sites and collected 816 photographs from 198 remote camera sites. From those photographs, 193 (24%) were of bears with 63 (33%) wearing color-coded marks.

The population estimate was 47 using Bailey's binomial model (95% C. I. = 38 - 57), 45 using the Minta-Mangel estimator (95% C. I. = 35 - 67), 43 using the Bowden estimator (95% C. I. = 27 - 69), and JoUy-Seber produced an average estimate of 34 bears (95% C. I. = 5-44).

I collected 1,258 telemetry locations from 21 radio-collared bears (12F: 9M) between 23 June and 12 December 1998. Annual home range size (95% minimum convex polygon) for males and females averaged 7.0 km2 and 4.2 km2, respectively. Home range overlap among females was extensive, especially in the Bluecat tract. Each female's home range in Bluecat overlapped with at least 6 other female home ranges. Where overlap occurred, it ranged from <1 to 100% with 27 of 46 overlaps being over ≥50%.

I recorded dispersal patterns for 8 yearling bears (5M: 3F). All yearling females remained in the tract of capture, as did 1 male. Four yearling males dispersed to other tracts resulting in the death of 2 of those individuals. Eleven bears (8M: 3F) were documented moving between isolated woodlots on 81 occasions and 34 (42%) of these movements were between woodlots connected by a forested corridor. The remaining movements were between isolated tracts not connected by a corridor. However, 28 (35%) were between woodlots <0.5 km apart and 19 (23%) movements were made exclusively by males. I also recorded 28 observations of male (n = 7) and female (n = 2) bears in forested corridors. Twenty-three (82%) of these were made by male bears.

I also monitored natality and cub survival. Eight radio collared bears and 1 free ranging bear were observed with litters totaling 16 cubs. Five cub deaths were recorded. Three cubs (unknown sex) died of unknown natural causes, and 2 cubs (1M: 1F) died of unknown causes after translocation conducted by the USFWS. I recorded 3 other mortalities of bears during this study. Two males (1 adult, 1 yearling) were killed in collisions with automobiles and 1 juvenile male bear was poached.

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