Michael J. Lacki

Day-roost characteristics of northern bats in mixed mesophytic forest

Management of forests to promote habitat needs of bats requires information on all life requisites of each species. Data on roosting habitat of northern bats (Myotis septentrionalis) is limited for eastern deciduous forests. We radiotracked 13 adult female and 2 adult male northern bats as they used 57 day roosts in mixed mesophytic forest in northeastern Kentucky from 18 May to 5 August 1998. Northern bats used day roosts in 12 species of trees, with sourwood (Oxydendrum arboreum) and shortleaf pine (Pinus echinata) each comprising 29.8% (n = 17/57) of the roost trees, respectively. Colonies, >1 northern bat, were predominantly found in cavities of hardwood snags (44.2%, n = 19/43) or under the bark of shortleaf pine snags (32.6%, n = 14/43). Snags possessing sloughing bark with branches absent were more frequently used as roosting sites by northern bats (52.9%, n = 18/34) than any other stage class of snag. Solitary bats were primarily found roosting in cavities of living hardwood trees (92.9%, n = 13/14). Roost trees of northern bats were not distributed equally among topographic locations, with roosts more frequently situated on upper slopes (45.6%, n = 26) and midslopes (38.6%, n = 22) than on lower slopes (15.8%, n = 9). Mean population size of colonies appeared to decline as summer progressed, with pregnant females using the largest colonies (x = 25,6 ± 10.2 bats), lactating females using intermediate-sized colonies (x = 13.5 ± 2.98 bats), and post-lactating females using the smallest colonies (x = 3.8 ± 1.66 bats). These data suggest that forest management practices that sustain diversity in tree species, tree-size class (3.1-55.8 cm dbh), and snag-condition class (stages 3 and 4) are necessary to provide habitat for northern bats in mixed mesophytic forests.

Selection of day roosts by red bats in mixed mesophytic forests.

Limited information exists on the choice of day roosts by red bats (Lasiurus borealis) in mature deciduous forests. We radiotracked 10 adult female and 4 adult male red hats as they used 44 day roosts in nived mesophytic forests in castern Kentucky during May through August 1996-97. On average (x ± SE). bats roosted 16.5 ± 0.3 to above ground in the outer foliage of the canopy of 13 different species of hardwood trees: no conifer or snag was used as a day roost. Roost trees were dominant and codominant trees averaging 10.5 1.9 cur dblt. Most roost trees 77.3% were on ridge tops of upland forests. Each hat used an average of 11 roost trees and switched roost trees every 2.3 days in an area <40 m 2 . Day roosts were 277 ± 30 m from lorest edge. with no roost located < 50 m from any edge. These data indicate that choice of day roosts In red bats inhabiting tracts of mature contiguous forest differs from those in fragmented habitats.

Short-term changes in bird communities in response to silvicultural prescriptions

Abstract Bird communities were surveyed on the Daniel Boone National Forest, Kentucky, using point-counts in May and June of 1993, 1994, and 1995. Sixteen stands were surveyed among four silvicultural prescriptions, including no-harvest, two-age high-leave harvest (i.e. 7 m2 residual basal area ha−1), two-age low-leave harvest (i.e. 3.5 m2 residual basal area ha−1) and clearcut harvest. Data were collected for 1 year preharvest (1993) and 2 years post-harvest (1994 and 1995). Pre-harvest surveys revealed no differences in abundance, richness or diversity of bird communities among stands. After harvest, all indices were higher for bird communities in harvested stands than in no-harvest stands, with no difference among clearcut or two-age stands. Two forest interior species and one interior edge species were negatively affected by timber harvest in some stands, whereas Hooded warblers (Wilsonia citrina) were detected most frequently in low-leave and high-leave harvested stands. Three shrub-scrub species were positively affected by timber harvest. The Brown-headed cowbird (Molothrus ater) was the most commonly detected species in all harvested stands after harvest. These data indicate that a shift to two-age harvest prescriptions on the Daniel Boone National Forest will not alleviate the negative short-term responses associated with fragmentation on forest interior species, and will continue to enhance conditions for species preferring early successional habitat.

Foraging areas and habitat use of the Virginia big-eared bat in Kentucky

The Virginia big-eared bat (Plecotus townsendii virginianus) is an endangered subspecies of Townsends big-eared bat. Little information exists about the movements and habitat requirements of these bats. We used radio telemetry to determine Virginia big-eared bat foraging area size and use of habitat in Daniel Boone National Forest (DBNF), Kentucky. We attached radio transmitters to 30 males in 1990 and 30 females in 1991. We monitored bats during 3 tracking periods each summer, tracking 9-11 bats during each period. Size of male foraging areas (87.4 ha, n = 6) in 1990 was not different from size of female foraging areas (121.9 ha, n = 13) in 1991 (P = 0.49)

RESPONSE OF NORTHERN BATS (MYOTIS SEPTENTRIONALIS) TO PRESCRIBED FIRES IN EASTERN KENTUCKY FORESTS

Abstract Prescribed fire is becoming a common management tool for restoring forests of North America; however, effects of prescribed fire on forest-dwelling bats remain unclear. During 2006 and 2007, we monitored prey availability, diet, foraging behavior, and roost selection of adult female northern bats (Myotis septentrionalis) before and after 2 prescribed fires in dissected terrain of the Red River Gorge on the Daniel Boone National Forest in eastern Kentucky. Size of home ranges and core areas did not vary between bats radiotracked before and after fires. Bats foraged more often in the vicinity of pine stands than hardwood or mixed stands, and along ridges and midslopes than lower slopes, regardless of burn condition. Home ranges were closer to burned habitats following fires than to unburned habitats. Abundance of coleopterans, dipterans, and all insects combined captured in blacklight traps increased following prescribed fires. Fecal samples of bats demonstrated lepidopterans, coleopterans, and dipterans to be the 3 most important groups of insect prey, with consumption of dipterans increasing after burning. Bats chose roosts that were taller in height and in earlier stages of decay than random snags, and after prescribed fires chose roosts in trees with a greater number of cavities and a higher percentage of bark coverage. More roosts were observed in burned habitats (74.3%; n  =  26) after fires than in unburned habitats (25.7%; n  =  9). The results of this work suggest that northern bats are tolerant to prescribed fire on the landscape pattern and scale observed in this study. Northern bats responded to habitat alterations resulting from prescribed fires through shifts in the location of foraging areas as bats tracked changes in insect availability, and through shifts in the selection of roost trees by occupying trees and snags possessing more potential roosting microsites.

Roost Selection, Population Size and Habitat Use by a Colony of Rafinesque's Big-eared Bats (Corynorhinus rafinesquii)

Abstract Rafinesques big-eared bat (Corynorhinus rafinesquii) is a species of concern throughout much of its range, with limited information available on the life history of this rare bat. We tracked patterns of population size, measured roost temperatures and used radiotelemetry to locate foraging areas of C. rafinesquii inhabiting a sandstone cave, which these bats used as both a hibernaculum and a maternity site. Counts of hibernating C. rafinesquii ranged from 14–49, with summer colony size reaching a maximum of 118 bats. Bats roosted in different rooms of the cave in winter and summer. Temperatures in a room used in winter were consistently cooler and less stable than temperatures in the room used as the maternity site. Size of foraging areas ranged from 61.6–225.3 ha, and distance of foraging areas from the roost varied from 0.12–1.22 km. We detected no bat >2.5 km from the roost of capture. Bats foraged along ridgelines supporting upland oak-hickory forest.

Effects of wild pigs on beech growth in Great Smoky Mountains National Park

Growth of trees in 9 high-elevation American beech (Fagus grandifolia) gaps in Great Smoky Mountains National Park (GSMNP) was examined from June to August 1982, for impact from rooting by wild pigs (Sus scrofa). Beech trees exhibited significantly greater shoot elongation (F2,6 = 7.71, P < 0.05) with increased exposure to rooting by wild pigs; however, tests for changes in radial increment (F,, = 5.42, P < 0.10) were not as significant due to confounding effects from elevation and stand age. Annular-ring widths of trees from young stands demonstrated greater variation in growth for years with pigs present compared to years before pigs inhabited the sites. Comparable changes were not observed for older stands. The growth responses of trees observed probably resulted from an enhanced nutrient mobilization in soils disturbed by pigs. J. WILDL. MANAGE. 50(4):655-659 Distribution of the wild pig has expanded to all continents as a direct consequence of introduction by man (Tisdell 1982). Wild pigs are abundant in several regions of the United States (Wood and Barrett 1979) and now occupy 13 areas managed by the U.S. National Park Service (Singer 1981). Impacts caused by the rooting of wild pigs are varied and, depending on the local situation, have been viewed as either detrimental or beneficial (Tisdell 1982). A management objective of national parks is to conserve native species in their natural environments. The presence of exotic wild pigs threatens the achievement of such an objective for GSMNP. Wild pigs in GSMNP have caused changes in herbaceous vegetation (Bratton 1974, 1975; Howe and Bratton 1976) and soils (Lacki and Lancia 1983, Singer et al. 1984). Rooting by wild pigs is known to damage tree roots and increase the amount of sprouting or root suckering (Huff 1977), but the responses by overstory components in forests of GSMNP have not been examined. To fully assess the implications of a resident population of wild pigs in GSMNP, the impact of these animals on all ecosystem components needs to be quantified. The objective of our study was to determine the effect of rooting by wild pigs on tree growth in the most disturbed forests of GSMNP. Our research was funded by the Natl. Park Serv. (NPS) through Uplands Res. Lab., GSMNP (NPS Contract X5460-0-2592) and, in part, by a Theodore Roosevelt Mem. Fund Grant to the senior author. This is Contrib. 10249 from the N. C. Agric. Res. Serv. journal series. We are indebted to R. J. Fredrickson and W. M. Whiteside for field assistance and to L. A. Nelson, K. H. Pollock, and W. L. Hafley of the Deps. Stat. and For. at North Carolina State Univ. for statistical advice. We are grateful to N. H. Shrimpton for measuring increment cores. We thank Uplands Res. Lab. and the Resour. Manage. Sect. GSMNP, and the Deps. For. and Zool. at North Carolina State Univ. for logistic support. Comments and suggestions were provided by C. L. Campbell, C. B. Davey, P. D. Doerr, J. D. Hair, R. Lea, and P. M. Vitousek.

Day-Roosting Habitat of Female Long-Legged Myotis in Ponderosa Pine Forests

Abstract We studied use of day roosts by adult, female long-legged myotis (Myotis volans) in 4 watersheds dominated by ponderosa pine (Pinus ponderosa) forest east of the Cascade Crest in Washington and Oregon, USA, 2001–2003. To investigate maternity habitat in managed, xeric forests we radiotracked 87 bats to 195 snag roosts and 34 rock crevices totaling 842 roost-days. Bats changed roosts every 2.7 ± 0.1 (SE) days and averaged 3.6 ± 0.3 roosts per bat. Roosts were 2.0 ± 0.1 km from capture sites, and bats moved 1.4 ± 0.1 km between successive roosts. Six bats (6.9%) day-roosted in rock crevices exclusively, 9 bats (10.3%) used snags and rock crevices, and the remaining bats (82.8%) day-roosted in snags exclusively. Most snag roosts were thick-bark ponderosa pine (n = 103; 52.8%) or thin-bark grand fir (Abies grandis) and white fir (Abies concolor) (n = 74; 37.9%). Over half of all snag roosts (n = 101; 52%) were used by solitary bats; 28 snag roosts (14%) housed >50 bats (large-flyout roosts). Ninety-three percent of large-flyout roosts were in ponderosa pine snags. Large-flyout roosts were larger, taller, and retained more exfoliating bark and total bark than small-flyout roosts (P < 0.05), and small-flyout roosts were larger, taller, and retained more exfoliating bark and total bark than random snags (P < 0.05). Snag roosts were closer to other snags, located in areas of greater snag density, with greater snag basal area and greater basal area of snags >25 cm diameter, and were lower in elevation than random snags (P < 0.05). Pregnant bats divided roost-days almost evenly between thick and thin-bark snags (52.7 vs. 47.3%), whereas lactating bats roosted in thick-bark snags more often than they did in thin-bark snags (80.3 vs. 19.7%, P < 0.0001). Pregnant bats roosted in both upslope and riparian zones (57.5 vs. 42.5%), but lactating bats spent more days roosting upslope than in riparian zones (73.1 vs. 26.9%, P < 0.0001). These findings suggest that reproductive female long-legged bats choose roosts relative to their changing physiological needs. We recommend that management of forests for sustaining habitat of female long-legged myotis in the east Cascades ensure the continued availability of both thick- and thin-bark snags in early stages of decay, in both riparian and upslope positions.

A prospective power analysis and review of habitat characteristics used in studies of tree-roosting bats

We identified 25 studies published between 1988 and 2001 that measured characteristics of roosting sites of tree-roosting bats, and where measures were compared to characteristics of random or available locations. The most frequently measured habitat characteristics were roost-tree diameter (n = 23), roost-tree height (21), roost-tree canopy cover (16), roost height (14), and slope (10). Habitat characteristics of the roost tree itself were measured more frequently than stand or landscape characteristics; a total of 31 different habitat characteristics was used to describe stand or landscape conditions as opposed to 23 different habitat characteristics used to describe features of the roost tree. The overall mean (± SE) number of habitat characteristics examined per study was 8.0 ± 1.1, with an average of 4.2 ± 0.7 characteristics reported to be significant (P < 0.05). Mean estimated effect size, or the absolute value of the difference between means divided by the population standard deviation, of habitat characteristics ranged from 0.83 to 1.52. A sample size of 11 radio-tagged bats was sufficient to achieve acceptable power, i.e., 0.80, for all habitat characteristics examined when only using the upper limit of the 95% confidence intervals for estimated effect sizes. In contrast, a sample size of 39 radio-tagged bats was sufficient in achieving the same level of power for only 50% of the habitat characteristics evaluated at the lower end of the 95% confidence intervals. We encourage researchers to conduct pilot studies, and estimate effect sizes and variances to assess the level of sampling effort required to evaluate habitat characteristics in studies of tree-roosting bats.

Social networks of Rafinesque's big-eared bats (Corynorhinus rafinesquii) in bottomland hardwood forests

Abstract Understanding social relationships and organization in colonial bat species can provide valuable insight into species ecology and potentially aid in conservation efforts of rare bat species. We applied social network analysis to describe social relationships and organization in 3 colonies of Rafinesques big-eared bats (Corynorhinus rafinesquii) roosting in bottomland hardwood forests in Kentucky. We radiotracked 48 adult big-eared bats to 64 day-roosts over 549 bat-days during the summers of 2009–2011. We measured homophily, network centralization, density, transitivity, and core–periphery structure of networks of bats sharing common roosts, and we measured degree centrality of nodes (bats or roosts) within networks. Patterns of ties within each colony were homophilous by sex (E-I index = −0.87). Males were consistently the least central nodes in bat networks. Bat network centralization ranged from 1.2% to 40% among colonies, and roost network centralization ranged from 17% to 40%. The colony exhibiting the least centralized and most dense bat network also occupied habitat with low roost availability. This roost network was highly centralized, with bats frequently aggregating at a single roost. The colony with the most centralized and least dense bat network occupied habitat with a greater availability of roosts, resulting in diffuse networks of bats and roosts. Transitivity decreased after young became volant in the colony with highest roost availability. Our findings suggest that social structure in colonies of Rafinesques big-eared bats is affected by the sex of individuals in colonies, reproductive season, and the preponderance of available day-roosting habitat.