Quantitative comparison of tree roosts used by red bats (Lasiurus borealis) and Seminole bats (L. seminolus)

Abstract

We radio-tracked 11 red bats (Lasiurus borealis) and 5 Seminole bats (L. seminolus) to 64 and 34 day roosts, respectively. Individuals of both species were found roosting within the canopy of the roost trees, clinging to leaf petioles or the tips of small branches (<4 cm in diameter). Red bats roosted primarily in hardwoods (97%), whereas the roosts of Seminole bats were located primarily in pines (94%). Ten of the 16 roost-site variables examined differed significantly between red bats and Seminole bats: number of trees in the overstory, overstory height, understory richness and diversity, overstory richness, diversity, and evenness, roost-tree diameter, percent canopy closure, and percentage of conifers in the overstory. These differences were related directly to the differential use of roosting habitats by the two species. The roosts of red bats were located in pine - mixed hardwood communities and bottomland hardwood swamps, while the roosts of Seminole bats were located in communities dominated by pines. To examine within-stand roost selection, the diameter, height, and species composition of roost trees used by red and Seminole bats were compared with those of neighboring trees. Roost trees of red and Seminole bats had significantly larger diameters and were significantly taller than surrounding trees. Day roosts of red and Seminole bats were located in 18 and 5 tree species, respectively. The tree species used differed significantly from expected for the red bat but not for the Seminole bat.