Status of an Anomalous Population of Northern Long-Eared Bats in Coastal North Carolina

Although previously well-documented in the mountains of the Blue Ridge Ecoregion of western North Carolina, the northern long-eared bat Myotis septentrionalis was only recently discovered in coastal North Carolina in 2007. After being listed as a federally threatened species in April 2015, a five-year effort of mist net surveys and tracking was initiated to better understand the species’ distribution and behavior in eastern North Carolina. Since 2015, 163 healthy northern long-eared bats have been captured, and the documented range of the species has expanded from 4 coastal counties to 19. Captures occurred in all months of the year and mostly occurred in or adjacent to wetland forests. Captures were limited to the Middle Atlantic Coastal Plain Ecoregion of the state, and the maximum distance from the Atlantic Ocean or associated sounds was <87 km. Northern long-eared bats have not been documented in the Southeastern Plains or Piedmont Ecoregions of North Carolina. The lack of captures in the middle portion of the state suggests geographically disjunct populations of the species in North Carolina. During late fall–winter netting and tracking, northern long-eared bats were observed to be active throughout most of the winter and roosted in trees. Across three late fall–winter seasons from 2015–2018, 43 northern long-eared bats were tracked to 165 winter roost trees. Most (94.6%) winter roost trees occurred in wetland forest. Winter roost trees varied greatly in species, diameter-at-breast-height, status (dead or live), and type of roost (cavity, crack, crevice, or exfoliating bark). The species’ lack of long-term hibernation in coastal North Carolina documents a vastly different survival strategy as opposed to the well-documented hibernation strategy the species is known to use in the rest of its range. This portion of the state is nearly devoid of caves or mines suitable for hibernacula, but also experiences milder winters with low-level insect activity. During spring 2019, 21 reproductive females were captured in the northernmost portion of the coastal plain of North Carolina and tracked to 64 maternity roost trees. Pregnant females began to be captured on April 25, and juveniles began to be captured on June 16. This indicates that pups are likely born in late May in the northern portion of the coastal plain of North Carolina, but birth likely occurs earlier in the southern portion of the coastal plain of the state. Most (92.2%) maternity roost trees occurred in wetland forest. Maternity roost trees varied greatly in species, diameter-at-breast-height, status, and type of roost. Swab samples collected during late fall–winter from 198 bats from species susceptible to white-nose syndrome provided no evidence of Pseudogymnoascus destructans. Since northern long-eared bats in coastal North Carolina are active most of the winter and not dependent upon caves or mines for hibernation, they are likely not susceptible to white-nose syndrome. With the species in sharp decline elsewhere due to white-nose syndrome, this coastal North Carolina population and a recently discovered coastal South Carolina population may serve as a refugium for the species.

YEAR-ROUND BRIDGE COLONY OF MEXICAN FREE-TAILED BATS (TADARIDA BRASILIENSIS MEXICANA) IN TRANS-PECOS TEXAS

Mexican Free-tailed Bats (Tadarida brasiliensis mexicana) from a bridge colony in Big Bend Ranch State Park, Presidio County, Texas were followed over two natal seasons sand two winters. For the period of this study, the bridge was being utilized as a maternity roost with a number of the young of the summer overwintering in each of the two winters examined. The site also was used by nonreproductive adult males during spring and summer. Adult bats left the bridge roost by mid-to-late summer, leaving only young of the summer at the bridge to exploit roost and local resources through the fall and winter. Young of the summer being left at the maternity roost to overwinter is a novel behavior for T. b. mexicana. Sex-and age-specific segregation of bats is inferred within the bridge roost.

Postnatal growth, wing development and age estimations in the Mediterranean horseshoe bat Rhinolophus euryale (Chiroptera: Rhinolophidae) in Kerend cave, western Iran

We quantified postnatal changes in body mass, length of forearm, length of total gap of the fourth metacarpal-phalangeal joint and changes in wing morphology, including the wingspan, wing area, handwing length, handwing area, armwing length, armwing area, aspect ratio and wing loading in Rhinolophus euryale in a maternity roost in Kerend cave, western Iran. Mean body mass of pups increased linearly until 23 days, when they achieved 74.29% of the mean mass of adult females (11.28±0.74 g, n=12). Rates of body mass gain and forearm growth during the early stage of postnatal growth were 0.36 g/day and 1.41 mm/day, respectively. Length of epiphyseal gap increased during the first 3 weeks and subsequently followed by a linear decrease until day 70 when it closed. Wing characteristics increased linearly until the age of the first flight, after which growth rates significantly declined (all p<0.05). Wing loading decreased linearly (−0.09 Nm−2/day) until 36 days of age and thereafter increased to a maximum of 6.56±0.30 Nm−2 at 80 days of age. We compare our results with data obtained from close-related bat species, particularly Rhinolophus mehelyi previously studied in a nearby area.

Physical and microclimate characteristics of Nyctophilus gouldi and Vespadelus vulturnus maternity-roost cavities

Context Tree cavities suitable to rear young are a key resource in managed landscapes to support viable populations of tree cavity-roosting bats. Little is known about the selection of cavities for maternity roosts, presumably because of the difficulty in accessing such roosts. Aims Our study investigated physical and microclimate characteristics of maternity roosts of two species, namely, Gould’s long-eared bat (Nyctophilus gouldi) and little forest bat (Vespadelus vulturnus). Methods Maternity-roost cavities were identified in a timber-production landscape in south-eastern Australia. Roost trees (V. vulturnus n=5; N. gouldi n=9) and a subsample of available cavity-bearing trees (n=16) were climbed to obtain cavity characteristics. Key results Vespadelus vulturnus used tree hollows exclusively, whereas N. gouldi used both tree hollows (n=7) and thick loose bark (n=2). No significant difference in roost-cavity characteristics was detected between the species. However, V. vulturnus selected significantly narrower cavity entrances (mean: 16±3mm) than those of the available cavities. Temperature did not differ between maternity roosts and available cavities when investigated after the maternity season. However, a V. vulturnus maternity roost occupied for 33 consecutive days was warmer than mean roost and available cavities, suggesting that long-term roost use may be influenced by the thermal property of a cavity. Conclusions Our study has provided the first detailed tree-cavity description of maternity roosts of N. gouldi and V. vulturnus. The nightly roost switching and the large variation of tree-cavity characteristics used by N. gouldi suggest that this species requires a high density of non-specific tree cavities that are large enough for colony formation, whereas preferred roost cavities for V. vulturnus are likely to be hollows comprising narrow entrances that facilitate long-term use. Implications Our results highlighted the likely importance of narrow roost entrances for V. vulturnus, presumably for predator protection, and the conservation of tree cavities large enough for colonies to congregate. The formation of such hollows is likely to take many decades. Poor silvicultural practices, land clearing and inappropriate management of veteran trees have the potential to have an impact on this hollow resource. Our study also highlighted the need to further assess the importance of cavity microclimate for maternity-roost selection in warm climates.

Guidelines for Defining Biologically Important Bat Roosts: A Case Study from Colorado

Conservation of roosts is regularly recommended as a strategy to decrease the risk of threats to local bat populations (e.g., white-nose syndrome). Determining whether a roost site plays a meaningful role in maintaining a local bat population can be difficult given the variability found in roost structure type, and use by season, duration, and sex. Here we provide land managers and biologists with guidelines to aid in the decision process for determining which roosts are biologically important in maintaining healthy bat populations at a local scale. We define methods for determining biologically important roost sites and provide a case study of their use on bat roosts in Colorado. To be considered biologically important, we suggest that a roost meet two primary criteria: 1) it is considered a hibernaculum, maternity roost, transient roost, colonial bachelor roost, or fall swarming site used by bat species that are gregarious roosters, hibernators, or are known to swarm, and 2) if the site is disturbed or lost, it could affect 5% or more of the local population of the species, as defined by the investigator. Additive measures to further evaluate the importance of the roost and assign higher conservation value include: 1) a roost used by a special status species and 2) large aggregations of bats where an estimated 20% or more of the local population is roosting or swarming at the site. We also provide definitions for the seasonality of roost types, examples of several real-life scenarios where management decisions have been made for roosts, and a worksheet that helps guide users through the process.

Bats of the city of Banská Bystrica, Central Slovakia (Chiroptera)

Based on published findings (1900–2010), unpublished data from museum specimens (1965–1999) and data from recent field survey (2006–2013), the presence of altogether 15 bats species was recorded from the urban area of Banská Bystrica in Central Slovakia. Nyctalus noctula, Vespertilio murinus, Pipistrellus pipistrellus, Eptesicus serotinus and Myotis daubentonii were found as common species in the area. Nyctalus noctula was a predominant species (D=67.4), followed by Vespertilio murinus (D=15.2) and Pipistrellus pipistrellus (D=9.8). The systems of concrete blocks of flats (attic ventilation holes, dilatation fissures, various systems of plumbing accessories, damages of buildings, etc.) represent the most important features of the artificial urban habitat for bats. Most frequently, the hibernation aggregations found in the buildings were formed by Nyctalus noctula, Vespertilio murinus and Pipistrellus pipistrellus, while the occurrence of Myotis myotis, M. mystacinus and M. emargiantus was only occasional. No maternity roost of bats was recorded in the city of Banská Bystrica.