Masters Theses

Date of Award

8-1996

Degree Type

Thesis

Degree Name

Master of Science

Major

Wildlife and Fisheries Science

Major Professor

Michael R. Pelton

Committee Members

Joe Clark, David Buehler

Abstract

I studied the effects of roads on the behavior and survival of black bears (Ursus americanus) at Marine Corps Base Camp Lejeune in Coastal North Carolina from May 1990 to December 1992. I used mark-recapture methods, radiotelemetry, and a Geographic Information System (GIS) for the study.

I estimated there were 16 bears on the study area in 1990. By 1992, the population likely was reduced to ≤6 bears (3.3 bears/100 km2), primarily from vehicle-kills. Since 1988, vehicle-kills accounted for 20 of 28 (71 %) of the total known mortality. The annual female survival rate was 71 % for female bears on Camp Lejeune. This is the lowest estimate of survival reported for females in a southeastern black bear population.

Telemetry revealed that movement and activity patterns of bears on Camp Lejeune are complex and dynamic. I hypothesize that the spatiotemporal orientation of preferred fall foods has resulted in increased bear movements. Furthermore, the separation of preferred foraging and bedding areas by high-speed highways may have attributed to vehicle-kills. Eighteen of 20 (90%) vehicle-kills occurred between August and December.

I determined the seasonal and annual diet of bears on Camp Lejeune from examination of 421 scats. Artificial foods comprised 5% of the annual diet by volume but may have been underestimated. In 90 of 553 (16.3%) times I monitored radio-collared bears, they were < 100 m from artificial food sources (landfill, dumpsters, and troop activity).

I determined the distribution of bears to secondary and primary roads with a GIS using chi-square analysis. In 62 of 82 (76%) seasonal tests, bears used habitats adjacent to secondary and primary road zones disproportionately (P < 0.05). Using Bonferroni Z-statistics, I determined the selection of individual road zones. Most noticeably, the < 100 m road zone was avoided the majority of the time and in all cases annually for both secondary and primary roads (P < 0.05).

Using a repeated measures analysis, I detected season and biological period effects in travel rates, as well as the frequency of secondary and primary road crossings (P < 0.05). Furthermore, bears did not cross secondary or primary roads randomly (P < 0.05).

The response/reaction behavior of bears to primary roads was more pronounced compared to secondary roads (i.e, nonpaved roads). I documented only 2 primary road crossings between 1100 and sunset. Bears crossed primary roads less frequently compared to secondary roads (P = 0.06). Primary road crossings occurred 44 % less frequently than simulated random primary road crossings. In contrast to primary roads, some bears used secondary roads as convenient travel corridors. Secondary road crossings only occurred 20% less frequently than simulated secondary road crossings.

I measured the distance to roads immediately before and after bears crossed. Bears were located further (x̄ = 216 m, SE = 96, n = 45, P = 0.017) from primary roads after crossing compared to distances before crossing. Furthermore, bears were located further from primary roads (x̄ = 719 m, SE = 68, n = 45) compared to secondary roads (x̄ = 446 m, SE = 20, n = 308) after crossing (P < 0.001).

Correlation analysis suggests that bears preferred to cross primary roads during low traffic volumes. Weekday traffic volume and the mean frequency of primary road crossings were inversely correlated annually (r = -0.39, n = 60, P = 0.002) and in spring (r = -0.60, n = 12, P = 0.038). Furthermore, correlation analysis also suggested that bears were less discriminating in crossing primary roads in early and late fall. Early and late fall travel rates were more strongly correlated with the frequency of primary road crossings (r = 0.79, P = 0.002; and r = 0.65, P = 0.02, respectively) compared to the frequency of secondary road crossings (r = 0.59, P = 0.044; and r = 0.62, P = 0.03, respectively). Furthermore, the frequency of secondary and primary road crossings were strongly correlated in all seasons except early fall (P = 0.117).

I used a GIS, chi-square analysis, and Bonferroni Z-statistics to determine that radio-collared black bears selected habitats for crossing primary roads (x2 = 211. 72, 6 df, P < 0.001). Bears preferred pocosins, drainages, and pure hardwoods and avoided habitat openings for crossing primary roads (P < 0.05).

Camp Lejeune may represent a worst-case scenario of habitat fragmentation and impediment to movements for a southeastern black bear population. Not only is Camp Lejeune highly isolated from other bear populations, but its interior is fragmented by high-speed highways. Due to the high density of roads on Camp Lejeune, bears were unable to shift home ranges to avoid high-speed highways. As a result, vehicle-kill mortality has not only caused the number of bears to decline on Camp Lejeune but is threatening to extirpate this population. To recover this population, I discuss strategies to reduce bear movements across high-speed highways and thus reduce vehicle-kills on Camp Lejeune.

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