Roost Ecology Research Articles

Multi-scale assessment of roost selection by 'ōpe'ape'a, the Hawaiian hoary bat (Lasiurus semotus).

The Hawaiian hoary bat (Lasiurus semotus; Chiroptera: Vespertilionidae), commonly and locally known as 'ōpe'ape'a, is a solitary, insectivorous, and foliage-roosting species distributed across a wide range of habitats in lowland and montane environments. The species, as with many others in the Hawaiian archipelago, are facing a suite of challenges due to habitat loss and degradation, introduced predators and pests, and climate change. An understanding of the roost requirements of foliage-roosting tree bats is critical to their conservation as these habitats provide several important benefits to survival and reproduction. Because little is known about 'ōpe'ape'a roost ecology and considerable effort is needed to capture and track bats to roost locations, we examined resource selection at multiple spatial scales-perch location within a roost tree, roost tree, and forest stand. We used a discrete choice modeling approach to investigate day-roost selection and describe attributes of roost trees including those used as maternity roosts. 'Ōpe'ape'a were found roosting in 19 tree species and in an assortment of landcover types including native and non-native habitats. Our results are largely consistent with findings of other studies of foliage-roosting, insectivorous tree bats where bats selected roost locations that may offer protection and thermoregulatory benefits.

Roost ecology, population size, behavioral patterns and morphometric analysis of Indian flying fox (Pteropus medius; Temminck, 1825) in the Goalpara District of Assam, India

Roost ecology, population size, behavioral patterns and morphometric analysis of Indian flying fox (Pteropus medius; Temminck, 1825) in the Goalpara District of Assam, India

Evening Bats Captured in a Managed Wildlife Refuge Used Trees in a Human-Dominated Landscape as Maternity Roosts

Abstract Similar to many chiropteran species, pregnant and lactating evening bats Nycticeius humeralis form maternity colonies to bear and raise their pups. Although evening bat maternity roosts have been studied in other locations, knowledge gaps exist regarding maternity roost site selection on the Gulf Coast of Texas, United States; thus, our objective was to quantify maternity roost characteristics of evening bats in this region. We radiotracked 11 female and subadult evening bats to 9 roosts during June and July 2018 and 2019 captured in San Bernard National Wildlife Refuge (SBNWR). No transmittered bats roosted in SBNWR and instead all roosts were located 3.6–4.5 km from the same capture site, within an 81-ha residential area of a 5,496-ha city. Five of the nine roosts were located in tall, live, live oak trees Quercus virginiana and one roost was in a residential home. Colony size of bats occupying the roosts ranged from 16 to 500+ bats. All evening bats, including those on properties to which we were denied access, stayed in roosts for the full life of the transmitter (5–21 d) and no roost switching occurred. Although evening bats used SBNWR, potentially for foraging, results suggest trees in the residential area provided suitable maternity roost characteristics. A lack of roost switching may suggest a lack of available roost trees in SBNWR and residential areas or the selected roost trees were high quality. We recommend future studies increase sample sizes of evening bat roosts on the Gulf Coast of Texas, as well as assessing roost site selection of evening bats and monitoring bachelor colony and evening bat winter roost ecology.

Roost Characteristics of a Tricolored Bat Perimyotis subflavus in the Missouri Ozarks

The tricolored bat (Perimyotis subflavus) once commonly occurred throughout the eastern and central United States, but is now experiencing range-wide population declines primarily due to white-nose syndrome and forest fragmentation. Conservation efforts for this species require more information regarding summer maternity roost characteristics, especially in the Ozark Highlands of Missouri, where the species has declined precipitously. Herein we report the capture and tracking of one female tricolored bat to two summer roosts in southeastern Missouri. Tree roosts differed by their substrates, as one was within a cluster of dead leaves on a snag and the other was located under exfoliating bark; otherwise, the roosts and surrounding vegetation were similar. Both roosts were located in large (>30 cm diameter breast height) oak (Quercus spp.) trees under a dense canopy of trees with similar basal areas. While our capture success was limited over two years, details regarding tricolored bat roost ecology are imperative for the species' conservation and management.

Summer Roosting Ecology of the Northern Yellow Bat and Tri-Colored Bat in Coastal South Carolina

Lasiurus intermedius (Northern Yellow Bat) and Perimyotis subflavus (Tricolored Bat) are species of conservation concern in South Carolina and are threatened by loss of roosting habitat. To better understand summer roost selection, we radio-tracked individuals to roost trees during May through August of 2018 and 2019. We characterized roost trees, sites surrounding roost trees, and unused but available trees for each roost occasion. We used discrete-choice models to test hypotheses of factors influencing roost-site selection. Tri-colored Bats used foliage and Tillandsia usneoides (Spanish Moss) in hardwood trees and selected trees with high densities of Spanish Moss. Northern Yellow Bats used dead palm fronds in Sabal palmetto (Cabbage Palm Trees) or Spanish Moss in trees with high densities of Spanish Moss. Our results suggest that conservation of maritime and bottomland forests with trees that have high densities of important roost structures like Spanish Moss and dead palm fronds would benefit these species.

REFUGIOS Y SITIOS DE PERCHA DE Saccopteryx bilineata Temminck, 1838 (Chiroptera : Emballonuridae) EN EL CARIBE COLOMBIANO

Saccopteryx bilineata is a bat of wide geographical distribution in the Neotropics, but in Colombia there is very little information about its biology and roost ecology. This contribution presents a description of the shelters that S. bilineata uses in the Colombian Caribbean region, especially in areas of tropical dry forest. Although it has been documented that it shares shelters with many species of bats, this work presents the first record where S. bilineata shares refuge with Molossus molossus and the use as shelters or roosting sites of species of Brownea ariza, Caesalpinea coriaria and Ceiba pentandra. The high ecological plasticity of the species is ratified in terms of the use of available environments and shelters, as well as cohabiting with other bat species.

Limited use of bat boxes in a rural landscape: implications for offsetting the clearing of hollow‐bearing trees

Bat boxes frequently form part of hollow‐bearing tree offsets; however, their effectiveness is poorly documented. We investigated the effectiveness of a bat box program designed to partially offset tree hollow loss from clearing for a coal mine. During the first year of monitoring, we detected bats in 5% of 1,308 box checks. Only 3 of 13 local tree cavity‐roosting bat species/species groups used boxes and occupancy was not strongly associated with modeled box and site attributes. In the second year, we tested two hypotheses that may explain the relatively low box use: (1) solar exposure of boxes was inadequate for heterothermic bats and (2) available box designs were of low suitability. Relocating boxes to increase solar exposure did not increase use, or enhance the temperature profiles of relocated boxes. Introduction of a new box design led to 11 times higher use compared with existing designs forNyctophilusspp. (long‐eared bat). Overall, our data suggest that the bat box program was ineffective due to few bat species using boxes, infrequent box use by three species, and rarity of maternity roosting. The knowledge gap of species‐specific box designs and roosting ecology limits the effectiveness of boxes to offset cleared hollow‐bearing trees. Lack of knowledge and the widespread use of bat boxes to offset lost tree hollows highlights the need to (1) rigorously protect hollow‐bearing trees and (2) advance our understanding of species‐specific roost ecology, box design preferences and mechanical hollow creation into trees, before artificial hollows can be considered a meaningful offset measure.

Ecological Networks between Tent-Roosting Bats (Phyllostomidae: Stenodermatinae) and the Plants Used in a Neotropical Rainforest

Roost ecology in bats is a complex interaction of behavioral, morphological and physiological adaptations, thus, there are many factors involved in roost selection by bat species. Approximately 22 species of bats are able to modify leaves to establish their roost, 17 of which are in the Neotropics. Although there are many studies of tent-roosting bats, this is the first describing the structure of the interaction between bats and the plants they are using as roosts. We describe a potential antagonistic network between these bats and the plants used for tent construction in La Selva Biological Station in Costa Rica. We calculated descriptors of the network such as the number of bats and plants interacting, as well as the number of pairwise interactions based on published records or direct observations. We also tested for connectance and nestedness in the network structure. We propose a name for this non-trophic antagonistic interaction, which is a structural antagonism, where bats damage the leaves, reducing their lifespan and the plant fitness. In La Selva the network is composed of eight bats and 45 plant species reported by 60 pairwise interactions. Only 2.16% of vascular plant species in La Selva are being modified as tents. The network had low connectance (0.167) and no significant nestedness or modularity. Considering the species richness of plants in La Selva, there are few links between tent-roosting bats and plants species, which shows the specialization of these interactions and the high dependence of most of these bats on a few plant species, even if they are very specific and temporary resources.

Interspecific differences and commonalities in maternity roosting by tree cavity-roosting bats over a maternity season in a timber production landscape

Understanding maternity roost requirements is fundamental to guide timber production forest management given such roosts are vital to sustain bat populations. We tracked lactating females of three tree cavity-roosting species: Gould's long-eared bat (Nyctophilus gouldi) (n = 7), eastern broad-nosed bat (Scotorepens orion) (n = 6) and little forest bat (Vespadelus vulturnus) (n = 25), over five weeks in young (predominately <5 years old) forest regenerating from heavy timber harvest in southeast Australia. We aimed to investigate interspecific maternity roost selection in a regenerating landscape and by doing so, increase our understanding of the three species’ roost ecology. Sixteen V. vulturnus, 15 N. gouldi and six S. orion unique maternity roost trees were located. Bats displayed a degree of maternity roost selection plasticity, however, interspecific differences were found. Nyctophilus gouldi roosted selectively in retained riparian buffers, in trees of high senescence and switched roosts every day. Vespadelus vulturnus roosted in logged areas and displayed high roost site fidelity, with one roost used for 33 consecutive days. Scotorepens orion selected large live trees of low senescence. The preliminary data for this species suggests that females roost most days in ‘primary’ roosts but display a roost switching behaviour conforming to the fission-fusion model. Dead trees were identified to be important for both N. gouldi and V. vulturnus. Historical and recent logging at our study area drastically reduced cavity-bearing tree density to 1.4 trees per hectare in the logging zones (outside of exclusion areas), potentially limiting local populations of tree cavity-roosting bats and other cavity-dependent wildlife. Our data demonstrate that forest management must consider a range of maternity roost requirements to accommodate differences among species and highlight the importance of exclusion areas for roost habitat. We propose that an expanded ‘retention forestry’ approach should be implemented in logged areas that includes in-perpetuity forest patch retention to increase habitat complexity and continuity.

Indiana bats roost in ephemeral, fire-dependent pine snags in the southern Appalachian Mountains, USA

The Indiana bat (Myotis sodalis), a species that is federally endangered in the U.S., is being impacted by white-nose syndrome and habitat loss across much of its range. A better understanding of summer roost ecology of the species will enable us to develop management strategies that promote summer survival for breeding adult females and their pups. We conducted a 5year investigation of Indiana bat roost habitat selection and roosting behavior in a large (>250,000ha) forested area of the southern Appalachian Mountains and compared our results to populations in different landscapes across the species’ range. From May to August 2008–2012, we attached radio transmitters to 50 adult females, 3 juveniles, and 7 adult males captured at sites on the Cherokee and Nantahala national forests and Great Smoky Mountains National Park. We radiotracked bats to 95 roosts and measured characteristics of trees, 0.1ha plots, and landscape attributes for 69 of these roosts and associated random trees. We used an AIC approach to compare 14 candidate conditional logistic regression models. The only plausible model, which carried 95% of total model weights, had 3 important terms. Indiana bats showed strong selection for yellow pine (Pinus subgenus Diploxylon) snags that were significantly taller than random trees and in areas with a greater number of snags within 0.1ha. During this study, tree and stand structure were more important for roost selection than larger scale factors and Indiana bats responded to a pulsed and highly ephemeral resource, dead yellow pines, which were a significant component of the large forest tracts. Roosting behavior differed from what has been observed for Indiana bats in other parts of the eastern U.S.; maternity colonies tended to be smaller (<25 bats, but as large as 75 bats prior to pups being volant) and bats were more nomadic, using each roost tree for only 2–3days on average and rarely for more than one year. The differences we observed in roosting behavior in the southern Appalachians suggest it would be wise to consider the broader landscape context when evaluating the roosting ecology of Indiana bats, as local forest types and disturbance events will affect stand structure and roost tree availability. Stand- and landscape-scale management practices that create or preserve large pine snags, such as prescribed fire, coupled with natural or manmade pulsed disturbances, should aid in the management and recovery of the Indiana bat in this region.

Use of a Multi-Tactic Approach to Locate an Endangered Florida Bonneted Bat Roost

Abstract Effective strategies for bat conservation require knowledge of species-specific roost ecology. Thus, conservation planning is difficult for species with poorly understood roost use, such as the federally endangered Eumops floridanus (Florida Bonneted Bat). Prior to this study, only 1 active natural roost had been documented throughout the Florida Bonneted Bat's geographic range. Search efforts to locate new roosts using several techniques have been unsuccessful. Here we present a simple methodology that we successfully implemented to locate a second Florida Bonneted Bat natural roost. Using acoustics, cavity searches, and emergence observations, we documented a colony of Florida Bonneted Bats roosting in a Pinus elliottii (Slash Pine) snag in Florida Panther National Wildlife Refuge in Collier County, FL. Our discovery highlights the importance of snags, and provides additional details to state and federal agencies tasked with species recovery.

Using thermal imaging cameras with radiotelemetry to locate roost sites of male wild turkeys

Thermal imagery is a relatively new technology to the wildlife field. Researchers have begun testing whether this tool can be used to increase detection rates for various wildlife species. Little research has been conducted on roost-site selection of eastern wild turkeys (Meleagris gallopavo silvestris), partially because locating roosting birds and viewing them in forested environments is impractical. We evaluated the efficacy of ground-based thermal imaging combined with radiotelemetry to locate roosting male turkeys in southwestern Georgia, USA, 2011–2013. Using radiotelemetry and thermal imaging, we successfully collected data on 74 of 79 attempts (93.7%) to locate roosting male turkeys and identify the roost tree the bird was using. Compared with other methods of viewing roosting turkeys using thermal imagery, our methods were more successful. We recommend that researchers consider using ground-based thermal imaging to conduct more detailed studies on roost ecology of wild turkeys. © 2014 The Wildlife Society.

The Role of Landscape Composition and Configuration on Pteropus giganteus Roosting Ecology and Nipah Virus Spillover Risk in Bangladesh

Nipah virus has caused recurring outbreaks in central and northwest Bangladesh (the "Nipah Belt"). Little is known about roosting behavior of the fruit bat reservoir, Pteropus giganteus, or factors driving spillover. We compared human population density and ecological characteristics of case villages and control villages (no reported outbreaks) to understand their role in P. giganteus roosting ecology and Nipah virus spillover risk. Nipah Belt villages have a higher human population density (P < 0.0001), and forests that are more fragmented than elsewhere in Bangladesh (0.50 versus 0.32 patches/km(2), P < 0.0001). The number of roosts in a village correlates with forest fragmentation (r = 0.22, P = 0.03). Villages with a roost containing Polyalthia longifolia or Bombax ceiba trees were more likely case villages (odds ratio [OR] = 10.8, 95% confidence interval [CI] = 1.3-90.6). This study suggests that, in addition to human population density, composition and structure of the landscape shared by P. giganteus and humans may influence the geographic distribution of Nipah virus spillovers.

Ecological factors associated with European bat lyssavirus seroprevalence in spanish bats.

Bats have been proposed as major reservoirs for diverse emerging infectious viral diseases, with rabies being the best known in Europe. However, studies exploring the ecological interaction between lyssaviruses and their natural hosts are scarce. This study completes our active surveillance work on Spanish bat colonies that began in 1992. Herein, we analyzed ecological factors that might affect the infection dynamics observed in those colonies. Between 2001 and 2011, we collected and tested 2,393 blood samples and 45 dead bats from 25 localities and 20 bat species. The results for dead confirmed the presence of EBLV-1 RNA in six species analyzed (for the first time in Myotis capaccinii). Samples positive for European bat lyssavirus-1 (EBLV-1)–neutralizing antibodies were detected in 68% of the localities sampled and in 13 bat species, seven of which were found for the first time (even in Myotis daubentonii, a species to date always linked to EBLV-2). EBLV-1 seroprevalence (20.7%) ranged between 11.1 and 40.2% among bat species and seasonal variation was observed, with significantly higher antibody prevalence in summer (July). EBLV-1 seroprevalence was significantly associated with colony size and species richness. Higher seroprevalence percentages were found in large multispecific colonies, suggesting that intra- and interspecific contacts are major risk factors for EBLV-1 transmission in bat colonies. Although bat-roosting behavior strongly determines EBLV-1 variability, we also found some evidence that bat phylogeny might be involved in bat-species seroprevalence. The results of this study highlight the importance of life history and roost ecology in understanding EBLV-1–prevalence patterns in bat colonies and also provide useful information for public health officials.

Roost use by bats in Espírito Santo, Brazil: comparison of a protected area, a rural landscape, and an urban landscape

Los murciélagos utilizan una variedad de refugios, con funciones diferentes e importantes en la ecología del grupo. El conocimiento de estos refugios es importante en su gestión y conservación. Este estudio se realizó en tres localidades de Espíritu Santo, sudeste de Brasil: (1) Colina de Vargas (una zona protegida), (2) un paisaje rural, y (3) un paisaje urbano. En estas tres áreas se llevó a cabo la búsqueda activa de refugiospara instalar entre una y cuatro redes de niebla (dependiendo del tamaño del refugio) cerca de la entrada principal del refugio. Las redes se mantuvieron activas 3-6 horas después del atardecer. Se encontró un total de 12 refugios, cuatro en cada área, incluyendo: huecos de árboles, follaje, cuevas, grietas de las rocas, edificios, casas abandonadas, puentes y tuberías de aguas pluviales. Este es el primer registro de refugio natural de Lonchorhina aurita.

Winter Roosting Ecology of Silver-Haired Bats in an Arkansas Forest

Although summer roosting by Lasionycteris noctivagans (Silverhaired Bats) has been studied in various ecological regions of North America, no quantitative studies have examined winter roost selection. We radiotracked 11 bats to 31 day-roosts during winter in forests of the Ouachita Mountains, AR. We quantified roost structures and examined the association between roosts and forest stands. We also examined effects of temperature on roost use. Ninety percent of roosts were in trees (5 species): 55% of all roosts were under loose bark on the bole of live overstory Pinus echinata (Shortleaf Pine), 3% of roosts were in a rock outcrop, and 6% were at ground level (under a tree root or in a cavity at the base of a live pine). Bats selected pine or pine-hardwoods stands >50 years old, and used forest stands 15–50 years of age less than their availability. Roost locations were influenced by temperature and solar radiation; most (90%) roosts were on southern topographic aspects, and bats roosted in the rock outcrop or on the ground on colder days (<5 °C). Retaining open pine and hardwood stands >50 years old on south slopes would likely maintain roosting habitat for wintering Silver-haired Bats in the Ouachita Mountains.

Ecology of Rabies Virus Exposure in Colonies of Brazilian Free-Tailed Bats (Tadarida brasiliensis) at Natural and Man-Made Roosts in Texas

Previous studies have investigated rabies virus (RABV) epizootiology in Brazilian free-tailed bats (Tadarida brasiliensis) in natural cave roosts. However, little is known about geographic variation in RABV exposure, or if the use of man-made roosts by this species affects enzootic RABV infection dynamics within colonies. We sampled rabies viral neutralizing antibodies in bats at three bridge and three cave roosts at multiple time points during the reproductive season to investigate temporal and roost variation in RABV exposure. We report seropositive bats in all age and sex classes with minimal geographic variation in RABV seroprevalence among Brazilian free-tailed bat colonies in south-central Texas. While roost type was not a significant predictor of RABV seroprevalence, it was significantly associated with seasonal fluctuations, suggesting patterns of exposure that differ between roosts. Temporal patterns suggest increased RABV seroprevalence after parturition in cave colonies, potentially related to an influx of susceptible young, in contrast to more uniform seroprevalence in bridge colonies. This study highlights the importance of life history and roost ecology in understanding patterns of RABV seroprevalence in colonies of the Brazilian free-tailed bat.

Roosting ecology and variation in adaptive and innate immune system function in the Brazilian free-tailed bat (Tadarida brasiliensis)

Bats have recently been implicated as reservoirs of important emerging diseases. However, few studies have examined immune responses in bats, and even fewer have evaluated these responses in an ecological context. We examined aspects of both innate and adaptive immune response in adult female Brazilian free-tailed bats (Tadarida brasiliensis) at four maternity roosts (two natural caves and two human-made bridges) in south-central Texas. Immune measurements included in vitro bactericidal ability of whole blood and in vivo T cell mediated response to mitogenic challenge. Bactericidal activity in T. brasiliensis varied with roosting ecology, but appears to be sensitive to colony-level effects. Blood from females living at one cave had significantly lower bactericidal ability than blood from females at three other sites. T cell mediated response in this species was associated with variation in roost ecology, with females from two caves having greater responses than females from two bridges. T cell mediated response and bactericidal activity were negatively correlated with one another within individuals that were tested for both. Variation in immunological response of T. brasiliensis is important for understanding the influence of the environment on the frequency and distribution of immunologically competent individuals and for understanding disease-host dynamics in this and other colonial species.

Roosting requirements of white tent-making bat Ectophylla alba (Chiroptera: Phyllostomidae)

Roosting ecology and its correlates are among the major forces driving the evolution of bats. However, roost ecology remains one of the most poorly understood topics on the basic biology of bats. Ectophylla alba is endemic to Central America with a very small distribution. This species generally modifies leaves of a certain size within the genus Heliconia. Here we explore this species' habitat preferences for the construction of its roosts. We identified three variables as the requirements of a suitable tent-building habitat: canopy coverage, understory coverage between 0–1 m of height, and density of Heliconia. Our results show that the process of habitat selection for roost construction is highly specialized to an intermediate stage of secondary succession, which in turn, makes Ectophylla even more vulnerable to extinction than previously believed.

Winter Roosting Ecology of Eastern Red Bats in Southwest Missouri

Abstract:Eastern red bats (Lasiurus borealis) have been found to overwinter in areas that can experience severe fluctuations in temperature. We examined the red bat's use of winter roosts in southwest Missouri, USA, for 2 winters (2003–2005). We found tree roosts in eastern red cedars (Juniperus virginiana) and hardwoods. Tree roost sites were located on the south side of trees, and we found roost trees on south‐facing slopes. Roost sites occurred more frequently in the location with least canopy cover. Bats switched from tree roosts to leaf litter roosts when ambient temperatures approached or fell below freezing. We found habitat characteristics and aspect to be determining factors in the selection of leaflitter roosts. Management of overwintering red bats requires a diverse forest structure, including canopy gaps, stand‐density variation, and leaf‐bearing trees, including oaks (Quercusspp.).