Roger W. Perry

Tree Roosting by Male and Female Eastern Pipistrelles in a Forested Landscape

Abstract Little information has been published on selection of tree roosts by eastern pipistrelles (Perimyotis subflavus) in forested environments, and no radiotelemetry-based studies have been conducted on males in forested settings. Therefore, we used radiotelemetry to characterize summer roost selection by 21 male (33 roosts) and 7 female (14 roosts) eastern pipistrelles during 6 years in a forested region of the Ouachita Mountains of Arkansas. All roosts were located in the vegetation of tree canopies; 50% of roosts of females and 91% of roosts of males were in dead leaves of deciduous trees. Three (43%) of 7 maternity colonies were in dead needles of large live pines (Pinus echinata); this is the 1st documented use of pines by this species for roosting. Males selected tree sizes randomly but females selected trees that were larger (P < 0.05) than random. For males, 87% of roosts were in oaks (Quercus), and males roosted at sites with more midstory hardwoods, more large pines in the overstory, less canopy cover, and farther from the nearest trees than random locations. In a landscape offering a diversity of forest habitats, eastern pipistrelles during summer roosted mostly in leaves of oaks in mature (≥50-year-old) forest with a relatively complex structure and a hardwood component.

Scale-Dependent Effects of Landscape Structure and Composition on Diurnal Roost Selection by Forest Bats

Abstract Forest management affects the quality and availability of roost sites for forest-dwelling bats, but information on roost selection beyond the scale of individual forest stands is limited. We evaluated effects of topography (elevation, slope, and proximity of roads and streams), forest habitat class, and landscape patch configuration on selection of summer diurnal roosts by 6 species of forest-dwelling bats in a diverse forested landscape of the Ouachita Mountains, Arkansas, USA. Our objectives were to identify landscape attributes that potentially affect roost placement, determine whether commonalities exist among species in their response to landscape attributes, and evaluate the effects of scale. We modeled roost selection at 2 spatial scales (250- and 1,000-m radius around each roost). For each species, parameters included in models differed between the 2 scales, and there were no shared parameters for 2 species. Average coefficients of determination (R2) for small-scale models were generally higher than for large-scale models. Abundance of certain forest habitat classes were included more often than patch configuration or topography in differentiating roost from random locations, regardless of scale, and most species were more likely to roost in areas containing abundant thinned forest. Among topographic metrics, big brown bats (Eptesicus fuscus) were more likely to roost at higher elevations; roosts of big brown bats, northern long-eared bats (Myotis septentrionalis), and Seminole bats (Lasiurus seminolus) were influenced by slope; and big brown bats, evening bats (Nycticeius humeralis), and Seminole bats were more likely to roost closer to water than random. Northern long-eared bats and red bats (Lasiurus borealis) were more likely to roost closer to roads, whereas eastern pipistrelles (Perimyotis subflavus) were more likely to roost further from roads than random. Common parameters in most models included 1) positive associations with group selection (5 of 6 species) and thinned mature forest (4 species) at the small scale; 2) negative associations with unmanaged mixed pine–hardwood forest 50–99 years old at the large scale (4 species); 3) negative association with stands of immature pine 15–29 years old at the small scale (3 species); and 4) a positive association with largest patch index at the large scale (3 species). Our results suggest that, in a completely forested landscape, a variety of stand types, seral stages, and management conditions, varying in size and topographic location throughout the landscape, would likely provide the landscape components for roosting required to maintain a diverse community of forest bats in the Ouachita Mountains.

Width of riparian buffer and structure of adjacent plantations influence occupancy of conservation priority birds

Conservation of biodiversity on forest landscapes dominated by plantations has become an increasingly important topic, and opportunities to maintain or enhance biodiversity within these forests need to be recognized and applied. Riparian buffers of mature forest retained along streams in managed forest landscapes offer an opportunity to enhance biodiversity across these landscapes. However, influence of buffer width and structure of adjacent plantations on habitat use by birds is not well understood. We modeled probability of occupancy, while accounting for variable detection probabilities, for 16 bird species of regional conservation importance in the Ouachita Mountains of Arkansas, USA. We examined occurrence of breeding birds in streamside management zone (SMZ) buffers embedded in three structural classes of pine plantation: young open-canopy, closed-canopy, and older thinned plantations. Our occupancy models included a positive association with SMZ width for nine bird species associated with mature forests. Models for three early successional species (prairie warbler [Dendroica discolor], white-eyed vireo [Vireo griseus], and northern bobwhite [Colinus virginianus]) included a negative association with SMZ width. Occupancy models for Acadian flycatcher (Empidonax virescens), summer tanager (Piranga rubra), pine warbler (Dendroica pinus), prairie warbler, and northern bobwhite also included structural condition of adjacent plantations, but most species did not appear affected by condition of surrounding plantations. We found diverse responses among species to width of retained SMZs and structure of adjacent plantations; some species apparently benefitted from SMZs >100xa0m wide, while others benefitted from narrow buffers. Furthermore, most species traditionally associated with mature forests were common in narrow SMZs, regardless of width. Thus, optimal width of SMZs relative to avian conservation depends on the species of greatest conservation interest.