Movement Ecology of Black Bears in a Fragmented Bottomland Hardwood Habitat in Louisiana

Twelve Louisiana black bears (Ursus americanus luteolus) were captured 18 times on a 350-km² study area in the Tensas River Basin in northeastern Louisiana during 1992 and 1993. The study area, owned by Deltic Farm and Timber Co., Inc., consisted of 4 bottomland hardwood habitat fragments, several smaller woodlots, and extensive agricultural fields.

A total of 3,748 locations were collected on 10 radio-collared bears (4 male, 6 female). Mean home ranges were 52.33 km² and 12.61 km² for males and females, respectively, and were largest during the fall. Home range overlap, particularly among females, suggested high intraspecific tolerance.

Bears generally were crepuscular, but shifted from more diurnal activity in summer to more nocturnal activity in fall. Hourly movement rates were not different between sexes except during September (F = 374 m/hr, M = 589 m/hr). Daily movement rates were greater for males than females (F = 1079 m/day, M = 1847 m/day). No differences were found between adult and subadults in terms of home range characteristics, movement rates or activity.

Males were more likely than females to travel to other habitat fragments (P = 0.025). Black bear use of bottmoland hardwood habitat fragments did not increase in proportion to the size of the fragment. Possible factors determining fragment use include human use of the habitat and differences in natural food sources. All bears used wooded drainages, apparently to facilitate travel across the study area and to act as staging areas for foraging in agricultural fields. Males were more likely to be found in agricultural fields and were found farther from wooded cover than females during field excursions. All bears were found foraging in harvested corn fields during the fall.

No adult mortality was recorded during the study; however, two bears were killed in vehicle collisions just prior to the commencement of the study. An unconfirmed bear-vehicle collision was reported in December 1993.

Of the 6 bears monitored during the winter of 1992-1993, 1 male and 2 females denned in hollow trees, and the remainder used brushpiles or open nests. All den sites were located in bottomland hardwood habitat. Mean litter size was 2 and ranged from 1 to 3 (N = 4).

No instances of bears leaving the study area were documented. Human development, including an interstate highway and several small communities, may inhibit movement between the study area and the less-fragmented bottomland hardwood habitat to the south, effectively isolating this remnant population.