Food Habits of Louisiana Black Bears (Ursus Americanus Luteolus) in Two Subpopulations of the Tensas River Basin

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ABSTRACT.-

The Louisiana black bear (Ursus americanus luteolus) is listed federally as a threatened subspecies and current information about food habits is necessary for developing a sound conservation strategy. We collected and analyzed 251 scats from bears in the Tensas River Basin (TRB) population in northeast Louisiana. We compared diets of the two subpopulations (Tensas and Deltic) of the TRB and we observed differences during summer and fall. We suggest that the greater diversity of mast consumed by bears on Deltic may provide demographic stability to this small isolated subpopulation. Across the TRB, corn (Zea mays) made up the greatest percentage volume of scats and dominated summer and fall diet, whereas beetles (Coleoptera) were the food item found most frequently in scats. Other important food items included: blackberries and dewberries (Rubus spp.), acorns (Quercus spp.), palmetto fruit (Sabal minor), grasses/sedges (Poaceae or Cyperaceae), herbaceous vegetation and other species of soft mast.

INTRODUCTION

Black bears (Ursus americanus) are opportunistic omnivores that eat a wide variety of plant and animal foods across their geographic range (Landers et al., 1979; Maehr and Brady, 1984; Hellgren and Vaughan, 1988; Boileau et al., 1994; Bull et al., 2001). Most studies have shown that bears eat a variety of hard and soft mast, herbaceous vegetation, insects and other animals, and that changes in diet usually reflect changes in seasonal availability of foods on the landscape (Landers et al., 1979; Hellgren and Vaughan, 1988; Roof, 1997; Pelton, 2000; Bull et al., 2001). In areas where bears and agricultural activities are in close proximity, bears often consume large amounts of cereal grains (e.g., corn, Zea mays; Landers et al., 1979; Hellgren and Vaughan, 1988; Anderson, 1997; Weaver, 1999). Food resources can influence space use (e.g., Powell et al., 1997), habitat preferences (e.g., Unsworth et al., 1989) and reproduction (e.g., Rogers, 1987) of black bears and, therefore, knowledge of dietary patterns of bears is important when studying the ecology of populations.

The Louisiana black bear (Ursus americanus luteolus) was once distributed across much of Louisiana, west Texas and east Mississippi (Hall, 1981), but only three isolated populations remain. Extensive habitat loss and excessive harvest probably led to the reduction in range and population numbers and, in 1992, the Louisiana black bear was listed as a threatened subspecies under the United States Endangered Species Act (Neal, 1992). Despite the conservation status, there is currently little published information regarding the ecology of this subspecies. Two unpublished studies during the 1990s provided information about Louisiana black bear food habits in the Tensas River Basin (TRB) population of northeastern Louisiana (Anderson, 1997; Weaver, 1999). However, current studies of black bear food habits in the TRB are needed, as data for the earlier studies were collected ≥10 y ago. Changes to the landscape of the TRB during the last decade from timber harvest and reforestation have potentially affected food habits of bears; therefore, a current assessment of diet is needed to aid in monitoring and conservation efforts (e.g., habitat restoration). Furthermore, there are two subpopulations of bears in the TRB (referred to as Tensas and Deltic) that are characterized by different landscapes and bear behavior (Benson, 2005), but previous studies in the TRB have not compared diets of bears in the two subpopulations. If dietary differences exist between subpopulations, this knowledge would provide a clearer understanding of the ecology of bears in this population and could increase the efficacy of management efforts. Therefore, our objectives were to: (1) describe the current diet of Louisiana black bears in the TRB and (2) compare seasonal diets of bears from Tensas and Deltic.

STUDY AREA

The TRB is located in northeastern Louisiana in the western floodplain of the Mississippi River. …