Roosting Ecology of Bats in a Disturbed Landscape Joshua B. Johnson Increased attention has focused recently on the conservation and management of bats because of their important ecological roles as nocturnal insectivores and as possible bio-indicator species. Worldwide, many bat species have experienced dramatic population declines attributed to numerous anthropogenic environmental changes such as conversion of forests to agricultural or residential uses, and water pollution. In the eastern United States, efforts to promote species recovery largely have focused on protection of hibernacula, which has led to increases in populations of several endangered species. Although protection of hibernacula is undoubtedly important, the full range of habitats used seasonally must be taken into account when considering effective conservation and management strategies. Unfortunately, recovery plans often simply rely on the paradigm of habitat preservation or passive management, rather than proactive attempts at habitat enhancement through modification and management. Indeed, active habitat management may be a more effective means by which to encourage recovery of bat species. Throughout the Appalachian Mountains and Central Hardwoods forest regions, insufficient retention and/or regeneration of hard-mast producing oaks (Quercus spp.) and hickories (Carya spp.) in both managed and unmanaged forest stands is a major concern of forest and wildlife managers. Oak regeneration can benefit from a combination of prescribed fire and forest canopy alteration. Following decades of fire suppression in eastern forests, using prescribed fire as a tool to restore or enhance oak-dominated communities is gaining widespread acceptance in the Appalachian Mountains and elsewhere. In addition to fire, overstory thinning by tree removal, girdling, or herbiciding of competitors, can augment oak seedling initiation and survival through reduced competition and increased canopy openness. These methods could increase snag abundance that in turn could benefit snag-dependent wildlife species, including bats. The potential of using prescribed fire to create suitable roost conditions, in either live trees or snags, for bats, largely is an unexplored, but a potentially contributory area of research. For tree-roosting bats, fire can enhance roosting habitat by creating snags and increasing solar radiation at existing roosts. In 2007 and 2008, I examined roost selection of forest-interior dwelling northern myotis (Myotis septentrionalis) maternity colonies in stands treated with prescribed fire (hereafter, fire) and in unburned (hereafter, control) stands on the Fernow Experimental Forest, West Virginia. Using radio telemetry, I tracked 36 female northern myotis to 69 roost trees; 25 in the fire treatment and 44 in the control treatment. Using logistic regression and an information-theoretic model selection approach, I determined that within the fire treatment, northern myotis maternity colonies were more likely to use cavity trees that were smaller in diameter, higher in crown class, and located in stands with lower basal area, gentler slopes, and higher percentage of fire-killed stems than random trees. Moreover, roosts often were surrounded by trees that were in the upper crown classes. In the control treatment, northern myotis were more likely to roost nearer the tops of larger diameter cavity trees in early stages of decay that were surrounded by decaying trees in the upper crown classes than random trees. Roost trees in the fire treatment were associated with larger overall canopy gaps than roost trees within the control treatment. Regardless of treatment, northern myotis maternity colonies roosted in black locust (Robinia pseudoacacia) in greater proportion than its availability. Ambient temperatures recorded at a subset of roost trees in fire and control treatments indicated that daily minimum temperatures were similar, but daily mean and maximum temperatures were higher in the fire treatments, possibly due to larger canopy gaps created by the senescence and decay of the surrounding fire-killed overstory trees. Northern myotis roost-switching frequency, distance between successive roosts, and duration of individual roost tree use were similar between the fire and control treatments, suggesting similar roost tree availability despite a significantly higher proportion of potential roost trees in the fire treatment. Northern myotis readily exploited alterations to forest structure created by the reintroduction of fire, which accelerated snag creation and enlarged existing or created new canopy gaps, but it remains to be determined if these conditions translate into increased recruitment and survivorship. The influences of reproductive status, weather, and roost tree characteristics on timing of emergence, intra-night activity, and entrance of northern myotis at their diurnal roost trees largely is unknown. I examined nocturnal activity patterns of northern myotis maternity colonies during pregnancy and lactation at diurnal roost trees situated in areas that were and were not subjected to recent prescribed fires at the Fernow Experimental Forest, West Virginia from 2007 to 2009. Data recorded from exit counts and acoustic sampling suggested that northern myotis colony sizes were similar between reproductive periods and roost tree settings. However, intranight activity patterns differed slightly between reproductive periods and roost trees in burned and non-burned areas. Weather variables poorly explained variation in activity patterns during pregnancy, but precipitation and temperature were negatively associated with activity patterns during lactation. Throughout the world, maternity groups of bats are known to conform to fission-fusion models; and the movements among roost trees of individual bats belonging to these nonrandomly assorting groups form networks of roost trees. That these roost networks may exist as scale-free networks where a central node roost tree is connected more highly to other roost trees suggests a relative importance among roost trees to bat maternity colonies. Also, forest disturbances such as prescribed fire may alter roost networks and characteristics of roost trees and central node roost trees. At the Fernow Experimental Forest in West Virginia, I examined roost networks of northern myotis in forest stands subjected to prescribed fire and those that were not in 2007–2009. I determined that northern myotis did conform to fission-fusion models, forming social groups whose roost areas and roost networks overlapped to some extent. Roost networks largely resembled scale-free network models, 61% of which had single identifiable central node roost trees on which the remainder of the roost trees in the network centered. In control, i.e., unburned, treatments, central node roost trees were in early stages of decay and surrounded by higher basal area than other trees within the networks. In prescribed fire treatments, central node roost trees were smaller in diameter, lower in the forest canopy, and surrounded by lower basal area than other trees in the networks. Compared to central node roost trees in control treatments, those in prescribed fire treatments had higher amounts of bark coverage. My results indicate that northern myotis form social groups that roost in networks of trees that center on a central node roost tree that is selected based on surrounding basal area and decay stage. Forest disturbances such as prescribed fire may result in changes to roost networks through inputs in suitable roost trees by senescence and creation of forest canopy gaps. Forest disturbances, particularly permanent land use conversions, may fragment, isolate, and concentrate summer populations of philopatric bats, potentially resulting in genetically definable subpopulations. Also, subpopulations may be distinguishable at large spatial scales, regardless of forest disturbances and other land use conversions. I examined genetic structuring of the forest-interior dwelling northern myotis at multiple spatial scales, from watershed to regional, in West Virginia and New York. I genotyped microsatellites at 18 nuclear loci from 174 individuals. In many cases, loci in subpopulations that I defined a priori based on spatial attributes departed from Hardy-Weinberg equilibrium; those loci that were in equilibrium were inconsistent at differentiating subpopulations based on spatial scale. My results indicate that some level of genetic structuring is evident among northern myotis, but this structuring could not be attributed solely to geographic location. It is likely that the ability to migrate relatively long distances, exploit small forest patches, and use networks of swarming sites located throughout the Appalachian Mountain range has allowed northern myotis to maintain high gene flow regardless of forest disturbances resulting in habitat patchiness at local and regional spatial scales. Understanding the management impact, positive or negative, of prescribed fire on endangered Indiana myotis (Myotis sodalis) roosting habitat is of paramount interest to resource managers in the Appalachian Mountains and elsewhere. From 2001 to 2009, we examined roost selection of Indiana myotis in burned and unburned forests in Tucker County, West Virginia. We radio-tracked 16 male and 1 female Indiana myotis to 54 roost trees; 17 in burned stands and 37 in unburned stands. In burned stands, Indiana myotis roosted exclusively in fire-killed maples (Acer spp.). In unburned stands, they roosted in live hickories, oaks, and maples. Roost trees in burned stands were surrounded by lower basal area and by trees in advanced stages of decay with larger canopy gaps than at randomly-located potential roost trees in burned stands or actual roost trees located in unburned stands. Compared to randomly-located potential roosts in unburned stands, roost trees in unburned stands were less

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Roosting ecology of bats in a disturbed landscape

The distribution of Kitti's Hog-nosed Bat (Craseonycteris thonglongyai) was conducted in Saiyok District, Kanchanaburi Province using harp traps between April 2010 and April 2013. This species was found in 11 out of 24 caves; 9 in military area and 2 in conservation area. A total of 672 bats were captured in this survey. The length of the bat forearms were 23.0-26.3 mm and adults weighed between 1.22 and 5.94 g. Results of this study provide information for conservation of this bat in the area.

https://www.vs.mahidol.ac.th/jaas/Files/Vol6No3/All%20Page%20JAAS%203(6)'13/Punyapat.PDF

The distribution of Kitti's Hog-nosed Bat (Craseonycteris thonglongyai) in Kanchanaburi Province.

The study of diversity of cave dwelling bats was conducted in Kanchanaburi Province using harp traps between April 2010 and July 2012. A total of 1,166 individuals belonging to 13 species from 8 genera and 7 families were recorded. Hog-nosed Bat (Craseonycteris thonglongyai), Croslet Horseshoe Bat (Rhinolophus coelophyllus) and Thomas's Horseshoe Bat (Myotis siligorensis) were the three most abundant species captured in the areas. Malayan Slit-faced Bat (Nycteris tragata) is new records for cave in Western Thailand. The bat species diversity in the underground cave was higher than the above ground cave. Results of this study provide information for future management and conservation of bats.

https://www.vs.mahidol.ac.th/jaas/Files/Vol5No3/Only%20Title%20JAAS%203(5)'12/02%20JAAS%203(5)%20K.Poonyapat.pdf

S. Jiemtaweeboon

Papers

The distribution of Kitti's Hog-nosed Bat (Craseonycteris thonglongyai) in Kanchanaburi Province.

Species diversity of cave dwelling bats in Kanchanaburi Province.