Masters Theses

Date of Award

8-1998

Degree Type

Thesis

Degree Name

Master of Science

Major

Wildlife and Fisheries Science

Major Professor

Michael R. Pelton

Committee Members

Joe Clark, John Philpot, David Buehler

Abstract

In eastern North Carolina, forested lands have changed in composition and been reduced in area. Agriculture and timber industries dominate the landscape and understanding the impacts of these industries on black bear ecology is key for managing bears in eastern North Carolina.

I investigated population size, adult survival, movements, and denning ecology of black bears (Ursus americanus) on the Neuse-Pamlico Peninsula (NPP) in eastern North Carolina, 1994-1996. Most of the NPP was privately owned and managed for agriculture and forest products. To represent the peninsula, I established 2 study areas, the Big Pocosin and Gum Swamp. The Gum Swamp contained a portion of a black bear sanctuary.

During the study, project personnel captured 77 bears 93 times in the Big Pocosin and 136 bears 200 times in the Gum Swamp. I estimated population size using a variety of capture-recapture and capture-resight models. At the end of the study, population density in the Big Pocosin and Gum Swamp was 0.53 and 1.35 bears/km², respectively.

I estimated adult survival for female bears using the Kaplan-Meier Staggered entry procedure. Annual survival of adult females in the Big Pocosin and Gum Swamp was 1.00 (95% CI* = 0.88-1.00) (D. Sylwester, Univ. of Tenn., pers. commun. via J. Philpot) and 0.83 (95% CI = 0.70-0.96), respectively. Female survival was greater at Big Pocosin compared to Gum Swamp (P = 0.02636). Hunting reduced the survival rate of females in the Gum Swamp from 0.94 to 0.83 and accounted for 5 of 8 of the mortalities. Combining study areas, annual survival of adult females was 0.90 (95% CI = 0.82-0.98).

To evaluate bear movement parameters, I calculated total movement, rate of travel, net movement, and range length from diel locations of bears on the NPP. Mean total movement and net movement was 3,611.4 m (SE = 228.2) and 871.0 m (SB = 133.5), respectively. Mean range length was 1,537.5 m (SE = 133.1) and mean rate of travel was 164.9 m/h (SE = 10.0). I found no difference (P = 0.5899) when comparing movement parameters between the Big Pocosin and Gum Swamp. However, I detected a difference (P = 0.0021) in movement parameters between summer and fall seasons, but the differences may have been an artifact of telemetry error (P = 0.6445).

To determine if bears moved randomly across the landscape or if they selected specific macrohabitat characteristics for movements, I compared 7 landscape characteristics between actual and random movement trajectories. I found a difference between actual and random trajectories (P = 0.0032); actual movement trajectories (x̄ = 257.8 m, SE = 7.7, n = 123) were farther from roads (P = 0.0011) than random trajectories (x̄ = 226.0 m, SE = 7.5, n = 123).

I investigated 20 nest dens, 2 excavated ground dens, and 1 tree den. I measured 6 microhabitat characteristics around nest dens and random sites. I compared the variables between pairs of nest and random sites. An overall difference was detected between nest and random sites (P = 0.0006). Shrub height was greater (P = 0.0022) at nest sites (x̄ = 74.3, SE = 3.8, « = 16) than random sites (x̄ = 47.6, SE = 5.3, n = 16). Similarly, stem density was greater (P = 0.0057) at nest sites (x̄ = 18.2, SE = 2.8, n = 16) than random sites (x̄ = 7.5, SE = 1.3, « = 16) and cover density was greater (P = 0.0001) at nest sites (x̄ = 71.7, SE = 3.8, n = 16) compared with random sites (x̄ = 40.8, SE = 2.2, n - 16).

The Big Pocosin and Gum Swamp study areas may represent both ends of the spectrum in terms of bear densities on the NPP. The population size found in the Gum Swamp exceeded previous estimates from other Southeastern coastal bear populations. Female survival rates on the NPP were similar to other bear populations, and the number of bears harvested and the spatial distribution of those harvested bears relative to local bear densities seems to be the best tools for managing mortality. Higher mortality of female bears residing near the border of the Gum Swamp sanctuary suggests that hunting effort or hunter success may not be constant across the NPP. Given the restricted movements and relatively small home ranges (Jones 1996) of bears on the peninsula, bear management units (EMU) and hunt clubs may provide a substantial area of refugia. In addition, roads may reduce the area of suitable habitat for bear movements. Thus, restricting road access may increase the amount of suitable bear habitat, particularly in areas with high road densities.

I hypothesize that the combination of agricultural food sources surrounded by relatively large blocks of forest, the patches of thick cover, the presence of sanctuaries and refugia, and a conservative harvest provide suitable conditions for black bear populations in intensively managed regions such as coastal North Carolina.

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