West nile virus antibodies in bats from New Jersey and New York

Eighty-three serum samples were obtained from big brown (Eptesicus fuscus), little brown (Myotis lucifugus), and northern long-eared (Myotis septentriotalis) bats (Chiroptera: Vespertilionidae), from New Jersey and New York (USA) between July and October 2002. Samples were analyzed for neutralizing antibodies to West Nile virus (WNV) and St. Louis encephalitis (SLE) virus. One little brown bat and one northern long-eared bat tested positive for WNV neutralizing antibodies. No bats had antibodies to SLE virus. This was the first large-scale investigation of WNV infection in bats in New Jersey. Additional work is needed to determine the effects of WNV on bat populations.     

Bat rabies in Illinois: 1965 to 1986

From 1968 to 1986, Illinois (USA) citizens and agencies submitted 4,272 bats to the Illinois Department of Public Health for rabies testing. Of this number, 6% tested positive, a rate comparable to similar studies from other parts of North America. Due to sampling biases, the true infection rate among bats in Illinois is probably lower than 6%. Additional analysis relied on a subsample (n = 2,433) of the specimens collected from 1965 to 1986. Prevalences were significantly different among years, but no linear trends were found over the study period. Evidence for a local outbreak of bat rabies was found. Prevalences for the species with sample sizes adequate for statistical analysis were, from high to low: hoary bat (Lasiurus cinereus), 11%; red bat (L. borealis), 5%; silver-haired bat (Lasionycteris noctivagans), 4%; little brown bat (Myotis lucifugus), 4%; big brown bat (Eptesicus fuscus), 3%; Keen's bat (Myotis keenii), 2%; and evening bat (Nycticeius humeralis), 2%. The higher prevalences found among the non-colonial species (hoary, red and silver-haired bats) were consistent with similar studies. Considerable annual variation in prevalences was found within species, and the prevalence rankings of the species varied over the study period. Prevalences were significantly higher in females (6%) than in males (4%) when species were pooled, but no significant differences between sexes were found within species. In contrast to the other species analyzed, all of which had sex ratios favoring females, the big brown bat sample had a large majority of males. Prevalences were significantly higher in adults (6%) than in juveniles (3%) when species were pooled. Within individual species, significant differences between age groups were found only for hoary and red bats; in two species, juveniles had higher prevalences. Above average prevalences were observed in May and August to November. Southern Illinois had the highest prevalences; prevalences were intermediate in the north and lowest in the central region. Overall, the patterns of rabies prevalence among bats submitted by the public in Illinois from 1965 to 1986 were similar to those reported from other parts of North America.     

Hematology, plasma biochemistry, and antibodies to select viruses in wild-caught Eastern massasauga rattlesnakes (Sistrurus catenatus catenatus) from Illinois

During the 2004 field season, blood was collected from Eastern massasauga rattlesnakes (Sistrurus catenatus catenatus) in the Carlyle Lake (Carlyle, Illinois, USA) and Allerton Park (Monticello, Illinois, USA) populations to derive baseline complete blood count and plasma biochemistry data and to assess the prevalence of antibodies to West Nile virus (WNV) and ophidian paramyxovirus (OPMV). Massasaugas were located for sampling through visual encounter surveys. Body weight, snout-vent length, total protein, globulins, sodium, and potassium were normally distributed among the survey population. Aspartate aminotransferase, creatine kinase, albumin, calcium, uric acid, white blood cell count, heterophils, lymphocytes, monocytes, eosinophils, and basophils were non-normally distributed within these animals. Female snakes had significantly shorter tail lengths; lower blood glucose, packed cell volumes, and absolute azurophil counts; and higher plasma calcium and phosphorus concentrations than did males. None of the snakes tested (n=21) were seropositive for WNV, whereas all (n=20) were seropositive for OPMV.     

Prevalence of west Nile virus antibodies in a breeding population of American Kestrels (Falco sparverius) in Pennsylvania

West Nile virus (WNV) has been identified in nearly 300 species of wild birds, including raptors, in North America since its introduction in New York City in 1999. American Kestrels (Falco sparverius) are susceptible to WNV infection, and the numbers of these birds have declined along the Atlantic coast in recent years. We examined the population biology and WNV exposure of kestrels breeding in the area surrounding Hawk Mountain Sanctuary in Kempton, Pennsylvania, USA. The reproductive biology of kestrels in this area was studied from 1992 until 2004. The number of kestrels breeding in nestboxes in 2004 was only 44% of the 6-yr mean observed prior to 1999. During the 2004 nesting season (study period: 8 June through 22 July 2004), adult kestrels were trapped near the site of their nestboxes. Blood samples were obtained, and serum antibodies specific to WNV were quantified using a plaque reduction neutralization test. Of 22 birds tested, 21 exhibited serum antibodies to WNV, suggesting that most (95%) of the adult kestrels in the population had been exposed to WNV.     

Alphacoronaviruses in New World bats: prevalence, persistence, phylogeny, and potential for interaction with humans

Bats are reservoirs for many different coronaviruses (CoVs) as well as many other important zoonotic viruses. We sampled feces and/or anal swabs of 1,044 insectivorous bats of 2 families and 17 species from 21 different locations within Colorado from 2007 to 2009. We detected alphacoronavirus RNA in bats of 4 species: big brown bats (Eptesicus fuscus), 10% prevalence; long-legged bats (Myotis volans), 8% prevalence; little brown bats (Myotis lucifugus), 3% prevalence; and western long-eared bats (Myotis evotis), 2% prevalence. Overall, juvenile bats were twice as likely to be positive for CoV RNA as adult bats. At two of the rural sampling sites, CoV RNAs were detected in big brown and long-legged bats during the three sequential summers of this study. CoV RNA was detected in big brown bats in all five of the urban maternity roosts sampled throughout each of the periods tested. Individually tagged big brown bats that were positive for CoV RNA and later sampled again all became CoV RNA negative. Nucleotide sequences in the RdRp gene fell into 3 main clusters, all distinct from those of Old World bats. Similar nucleotide sequences were found in amplicons from gene 1b and the spike gene in both a big-brown and a long-legged bat, indicating that a CoV may be capable of infecting bats of different genera. These data suggest that ongoing evolution of CoVs in bats creates the possibility of a continued threat for emergence into hosts of other species. Alphacoronavirus RNA was detected at a high prevalence in big brown bats in roosts in close proximity to human habitations (10%) and known to have direct contact with people (19%), suggesting that significant potential opportunities exist for cross-species transmission of these viruses. Further CoV surveillance studies in bats throughout the Americas are warranted.     

Serologic evidence of West Nile virus infection in black bears (Ursus americanus) from New Jersey

Serum samples obtained from 51 free-ranging black bears (Ursus americanus) in northwestern New Jersey in February and March 2002 were analyzed for neutralizing antibodies to West Nile virus (WNV) and St. Louis encephalitis virus. Three (6%) of the black bears tested positive for WNV-neutralizing antibodies. One additional sample was positive for flavivirus-neutralizing antibodies but could not be differentiated for a specific virus type. This is the first report of WNV infection in black bears.     

Rabies in insectivorous bats of western Canada, 1979 to 1983

A total of 1,745, 362, and 536 bats collected in Alberta, British Columbia, and Saskatchewan, respectively, was tested for rabies virus between 1979 and 1983. Only one (0.1%) of 769 bats collected at random from buildings was infected with rabies virus in contrast to 95 (5%) of 1,874 symptomatic, rabies-suspect bats submitted for testing. The pattern of infection in the rabies-suspect bats was similar in Alberta and Saskatchewan, but differed in British Columbia. Rabies was diagnosed in four species of bats in each of Alberta and Saskatchewan, but in seven species in British Columbia. Annual prevalence in rabies-suspect bats was similar in colonial species within each province. Rabies was found rarely in suspect little brown bats (Myotis lucifugus) (less than 1%). In suspect big brown bats (Eptesicus fuscus), the prevalence was low in Saskatchewan (3%), moderate in Alberta (10%), and high in British Columbia (25%). Big brown bats accounted for over 55% of the rabid bats detected in each province. Annual prevalence reported in silver-haired bats (Lasionycteris noctivagans) and hoary bats (Lasiurus cinereus) was variable in all three provinces. Rabies is enzootic in northern insectivorous bats.     

Antibodies to Pseudogymnoascus destructans are not sufficient for protection against white‐nose syndrome

White‐nose syndrome (WNS) is a fungal disease caused by Pseudogymnoascus destructans (Pd) that affects bats during hibernation. Although millions of bats have died from WNS in North America, mass mortality has not been observed among European bats infected by the fungus, leading to the suggestion that bats in Europe are immune. We tested the hypothesis that an antibody‐mediated immune response can provide protection against WNS by quantifying antibodies reactive to Pd in blood samples from seven species of free‐ranging bats in North America and two free‐ranging species in Europe. We also quantified antibodies in blood samples from little brown myotis (Myotis lucifugus) that were part of a captive colony that we injected with live Pd spores mixed with adjuvant, as well as individuals surviving a captive Pd infection trial. Seroprevalence of antibodies against Pd, as well as antibody titers, was greater among little brown myotis than among four other species of cave‐hibernating bats in North America, including species with markedly lower WNS mortality rates. Among little brown myotis, the greatest titers occurred in populations occupying regions with longer histories of WNS, where bats lacked secondary symptoms of WNS. We detected antibodies cross‐reactive with Pd among little brown myotis naïve to the fungus. We observed high titers among captive little brown myotis injected with Pd. We did not detect antibodies against Pd in Pd‐infected European bats during winter, and titers during the active season were lower than among little brown myotis. These results show that antibody‐mediated immunity cannot explain survival of European bats infected with Pd and that little brown myotis respond differently to Pd than species with higher WNS survival rates. Although it appears that some species of bats in North America may be developing resistance to WNS, an antibody‐mediated immune response does not provide an explanation for these remnant populations.     

Bat community structure in an urban park

In summer 1990, we mist-netted bats on 35 net-nights, for 4 h each night, along tributaries of the River Rouge in surburban Detroit, Michigan, USA The floodplains of these nvers are preserved as parkland We compared elements of bat community structure in these urbanized park areas to that of rural areas For the rural data set, we used mist-netting data obtained previously on 53 net-nights in southern Michigan using a similar protocol Mean number of bats captured per night was lower in urban compared to rural areas (13 vs 46) Species diversity (Simpson Index) was lower in the city (0.53 vs 0.28) as was species evenness (0.66 vs 0.36) The big brown bat Eptesicus fuscus made up 65% of the catch m rural areas but 83% in the city The red bat Lasirus borealis represented 18% of all bats m rural areas and 13% in the city The proportion of sites where the big brown bat was captured was significantly lower in the city (51% vs 74%) The proportion of sites that yielded red bats also declined, from 52% along rural nvers to only 14% in the city Sex ratio of adult big brown bats did not differ between urban (43% male) and rural (32% male) sites The ratio of juvenile big brown bats to adult females was significantly lower in the city (1.21 vs 30.77) Our data suggest that urbanization is a threat to insectivorous bat communities and leads to decreased overall abundance, decreased species diversity, and possibly lower reproductive success of those that are present     

Virologic and serologic survey for eastern equine encephalomyelitis and certain other viruses in colonial bats of New England.

To test the hypothesis that hibernating colonial bats serve as an overwintering reservoir host of eastern equine encephalomyelitis (EEE) and certain other arthropod-borne viruses in southern New England, 1128 bats of 4 species were collected from 1966 through 1976. Blood and tissue samples and ectoparasites from these bats were tested in suckling mice, wet chicks, and/or chick-embryo tissue cultures for virus. Rabies, the only virus isolated, was recovered from the brain, salivary glands, and brown fat of an apparently healthy adult male Myotis keenii found hibernating in western Massachusetts.     

White-nose syndrome and wing damage index scores among summer bats in the northeastern United States

White-nose syndrome (WNS) adversely affects millions of bats hibernating in caves of the eastern United States. Beginning in 2009, the US Fish and Wildlife Service supported use of a wing damage index (WDI) scoring system (scale of 0 to 3, or no damage to severe) to assess wing damage of bats captured during summer. Based on bat captures at 459 mist net sites in Pennsylvania, New York, Maryland, Virginia, and New Jersey, USA, we questioned whether WDI scores varied by species group, date, and distance to the closest known affected hibernaculum. We also compared relative health (body mass index [BMI] scores) to WDI scores. Of 3,419 bats (nine species), only four individuals (0.1%; little brown [Myotis lucifugus] and northern bats [Myotis septentrionalis]) were scored as a 3 and 47 (1.4%; big brown [Eptesicus fuscus], little brown, and northern bats) as a 2. All tree bats (eastern red [Lasiurus borealis], hoary [Lasiurus cinereus], and silver-haired bats [Lasionycteris noctivagans]) scored a 0 or 1, suggesting that these species were not affected by WNS. The average WDI score decreased as summer progressed, although trends were weak. Average WDI score and number of bats with class 2 and 3 damage increased with proximity to a known WNS-positive hibernaculum. Similarly, the number of bats with severe wing damage (scoring 2 or 3) was greater at sites closer to infected hibernacula, but little variance was explained by the trend. When species-specific BMI was examined, trends were consistent by sex (female BMI scores were higher than those of males), but no relationship was discovered between BMI and WDI scores. We conclude that, at this larger geographic scale, WDI is not a clear indicator of bat health.     

Neutralising antibodies for West Nile virus in horses from Brazilian Pantanal

Despite evidence of West Nile virus (WNV) activity in Colombia, Venezuela and Argentina, this virus has not been reported in most South American countries. In February 2009, we commenced an investigation for WNV in mosquitoes, horses and caimans from the Pantanal, Central-West Brazil. The sera of 168 horses and 30 caimans were initially tested using a flaviviruses-specific epitope-blocking enzyme-linked immunosorbent assay (blocking ELISA) for the detection of flavivirus-reactive antibodies. The seropositive samples were further tested using a plaque-reduction neutralisation test (PRNT90) for WNV and its most closely-related flaviviruses that circulate in Brazil to confirm the detection of specific virus-neutralising antibodies. Of the 93 (55.4%) blocking ELISA-seropositive horse serum samples, five (3%) were seropositive for WNV, nine (5.4%) were seropositive for St. Louis encephalitis virus, 18 (10.7%) were seropositive for Ilheus virus, three (1.8%) were seropositive for Cacipacore virus and none were seropositive for Rocio virus using PRNT90, with a criteria of ≥ four-fold antibody titre difference. All caimans were negative for flaviviruses-specific antibodies using the blocking ELISA. No virus genome was detected from caiman blood or mosquito samples. The present study is the first report of confirmed serological evidence of WNV activity in Brazil.     

Urban Maternity-Roost Selection by Big Brown Bats in Colorado

Abstract: Despite prevalent use of anthropogenic structures by bats and the associated implications for public health, management, and bat conservation, very little quantitative information exists about urban roost characteristics and their selection by bats. During the summers of 2001 to 2004 we conducted fieldwork in Fort Collins, Colorado, USA, situated on the northern end of Colorado's Front Range, to address questions of roost selection by the big brown bat (Eptesicus fuscus). The city has experienced its greatest growth in the past half century, with its population increasing by 30% in the last decade. Similar growth in new buildings has occurred, with the number of new housing permits issued annually doubling in the past decade. We located 142 roosts using radiotelemetry or by citizen calls in response to a newspaper article and flyers. To determine characteristics of roost selectivity by bats, we compared variables for known maternity roosts and randomly selected buildings at microhabitat and landscape scales using logistic regression; we used an information theoretic approach to determine which variables were most important. We considered 44 and 100 buildings in the microhabitat and landscape scale analyses, respectively. At the microhabitat scale maternity roosts had exit points with larger areas that were higher from the ground and had warmer average temperatures than randomly selected buildings. At the landscape scale distances to similarly categorized roosts were smaller, and urbanization variables such as lower building density, higher street density, and lower traffic count density were most important. Results for variables important to urban-roosting big brown bats were often analogous to studies that characterized maternity roosts found in tree snags and rock crevices. In addition, changes in the landscape, not only in the form of anthropogenic structures but also in water availability and vegetation structure such as riparian forests, may have led to population increases and range expansions of the big brown bat. Because big brown bats appear to selectively choose specific combinations of characteristics found at maternity roosts, not all available structures can be considered suitable and exclusion from established maternity roosts may negatively impact bat populations.     

A tale of two siblings: multiple paternity in big brown bats (Eptesicus fuscus) demonstrated using microsatellite markers

In many bat species, the opportunity for sperm competition or other mechanisms of post-copulatory paternity biasing is thought to be great, due to the long delay between copulation and fertilization, demonstrated sperm storage capabilities, and observed promiscuity. We present the results of the first study to assess whether litters of big brown bats (Eptesicus fuscus) containing dizygotic twins share the same father. We sampled 26 mother-offspring triads from three colonies in Indiana and Illinois, as well as 299 additional adults (237 females and 62 males) from these colonies and six other maternity colonies in the same area in 1997-1998. All individuals were genotyped at nine highly variable autosomal microsatellite loci and one X-linked locus. We assessed multiple paternity using autosomal and X-linked locus exclusions, and using maximum-likelihood methods. All methods confirmed multiple paternity within litters, and the maximum-likelihood analyses indicated that almost half of the sampled litters were composed of maternal half-siblings rather than full-siblings. Our results highlight the potential importance of post-copulatory mechanisms of paternity determination in the mating system of big brown bats, and have important implications for gene flow and population structuring in this species.     

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.     

Female big brown bats, Eptesicus fuscus, recognize sex from a caller's echolocation signals

The echolocation calls of bats function in prey capture and navigation but are not commonly regarded as communicative signals. However, because bats' echolocation calls show patterns of variability, they may transmit information about a bat, such as its age, individual identity or sex. For echolocation calls to function in this manner, variation in calls must be reliably linked to the characteristics of the bat, as has been shown in a number of studies. However, few studies have asked whether bats respond to this variation. We tested whether female big brown bats can identify the sex of an unfamiliar bat from playbacks of its echolocation calls. Playback consisted of a 30-s preplayback period, a 60-s playback period of either male or female echolocation calls, and a 30-s postplayback period. In the playback and postplayback periods the vocalization rates of female bats changed significantly relative to the preplayback period depending on the sex of the playback stimulus, indicating that they could determine sex from the echolocation calls. These findings support the possibility that echolocation calls play a role in communication in big brown bats.     

Exposure of Eurasian magpies and turtle doves to West Nile virus during a major human outbreak, Greece, 2011

A major number of West Nile virus (WNV) infections in humans occurred in 2010 in northern Greece, with 262 laboratory confirmed cases. In 2011, fewer cases were reported, but the pattern was more dispersed throughout the Greek mainland. Isolated strains were similar to lineage 2 strains detected in previous years in Austria and Hungary from birds of prey. We conducted a serological surveillance study on hunter-harvested wild birds, to determine possible exposure of avian species during the current outbreak. Serum samples from a total of 113 Eurasian magpies and 85 turtle doves (abundant resident and migratory avian species, respectively, with potential roles in WNV epidemiology) were tested. These birds were hunter-harvested during 2011 from various prefectures both affected and not affected by the WNV outbreak in Greece. Sera were tested for the presence of WNV IgG antibodies by indirect immunofluorescence assay (IFA). Verification of positive results by a micro-virus neutralization test (VNT) was also performed. A total of 23 out of 113 (20.4%) Eurasian magpies and 6/85 (7.1%) turtle doves were found positive. Results showed association of human cases with wild birds’ exposure to the virus; no avian sera were found positive in prefectures not affected by the WNV outbreak. In contrast, positive avian sera were found in every prefecture that human WNV cases occurred in 2011. High seroprevalence in Eurasian magpies suggests high activity of WNV in the areas. Findings of past exposure of migratory birds like turtle doves to WNV upon their arrival in resting areas in Greece suggest various avian species with similar migration traits as target species for viral isolation studies, as they can be considered candidates for the introduction of WNV lineage 2 in Greece from Central Europe.     

Disease‐related population declines in bats demonstrate non‐exchangeability in generalist predators

The extent to which persisting species may fill the functional role of extirpated or declining species has profound implications for the structure of biological communities and ecosystem functioning. In North America, arthropodivorous bats are threatened on a continent‐wide scale by the spread of white‐nose syndrome (WNS), a disease caused by the fungus Pseudogymnoascus destructans. We tested whether bat species that display lower mortality from this disease can partially fill the functional role of other bat species experiencing population declines. Specifically, we performed high‐throughput amplicon sequencing of guano from two generalist predators: the little brown bat (Myotis lucifugus) and big brown bat (Eptesicus fuscus). We then compared changes in prey consumption before versus after population declines related to WNS. Dietary niches contracted for both species after large and abrupt declines in little brown bats and smaller declines in big brown bats, but interspecific dietary overlap did not change. Furthermore, the incidence and taxonomic richness of agricultural pest taxa detected in diet samples decreased following bat population declines. Our results suggest that persisting generalist predators do not necessarily expand their dietary niches following population declines in other predators, providing further evidence that the functional roles of different generalist predators are ecologically distinct.     

Predictive Occurrence Models for Bat Species in California

Abstract: The ability to accurately predict the potential occurrence of species of management concern is useful for wildlife managers, particularly for those whose management activities involve large areas where sampling is difficult due to logistical or financial constraints. During the summers of 2002 and 2003, we used mist nets to capture bats (Myotis yumanensis, M. californicus, M. evotis, M. thysanodes, Eptesicus fuscus, Lasionycteris noctivagans, Tadarida brasiliensis, Antrozous pallidus, Lasiurus borealis, and Lasiurus cinereus) in Whiskeytown National Recreation Area in north-central California, USA. We used landscape-scale variables, logistic regression, and Akaike's Information Criterion (AIC_c) to model species distributions and produce spatially discerning predictive occurrence maps. We developed a priori models that we used to determine which landscape-scale variables best discriminated between capture sites and non-capture sites. The odds of capturing a bat were 3.3 greater when total edge increased by 10,000 m, whereas for Yuma myotis (Myotis yumanensis), the odds of predicting presence were 0.2 greater when distance to lakes and ponds decreased by 2,000 m. Elevation was important in predicting the distribution of silver-haired bats (Lasionycteris noctivagans) and big brown bats (Eptesicus fuscus). Increasing elevation by 400 m decreased the odds of capturing a silver-haired bat by 0.1 and a big brown bat by 0.4. Classification accuracy for our models ranged from 80.9% for all bat species combined to 72.3% for Yuma myotis and silver-haired bats. Predictive occurrence models can be valuable to bat conservation efforts because they provide spatial data important for evaluating the effects of management activities on species distributions.