Influences of island characteristics on community structure and species incidence of desert bats in a near-shore archipelago, Baja California, Mexico

Island biogeography has strongly influenced the study of biodiversity because archipelagos provide natural model systems for investigating patterns of diversity and the processes that shape ecological communities. I investigated the influence of area and isolation of islands (n = 32) in the Gulf of California, Mexico on patterns of richness, nestedness, and incidence of desert bats to determine factors important in shaping community structure and patterns of occurrence of bats in a naturally insular landscape. Species richness of bats was positively influenced by island size and declined with isolation from the Baja peninsula in two distinct subarchipelagos. Southern islands, which are associated with greater density of vegetation from summer rainfall, supported more species than dry, barren islands in the northern subarchipelago, suggesting that both area and habitat characteristics contribute to species richness of bats. Community composition of bats was nested by area and isolation, such that species found on smaller and more isolated islands were subsets of communities found on large, less isolated islands that harbored higher richness. The influences of area and isolation on community nestedness suggest species differ in immigration and persistence rates on islands. Bat communities were also nested at 27 sites in coastal habitat on the Baja peninsula, indicating that nestedness may occur in contiguous habitats that lack immigration and extinction filters. Probability of species occurrence on islands was influenced by area for five species of insectivorous bat (Pipistrellus hesperus, Myotis californicus, Macrotus californicus, Antrozous pallidus, and Mormoops megalophylla), suggesting occupancy of islands by these species is limited by resource requirements. The threshold of island size for occupancy of most species was ca. 100 ha, which is similar to area thresholds of incidence for many landbirds in the same archipelago. Isolation also influenced incidence of insectivorous bat species. My research shows that area and isolation influence both community structure and occupancy of bat species in a near-shore archipelago. My results raise important questions about connectivity and persistence of populations of bats in isolated habitats, especially when patch size is small

Limited refugia and high velocity range-shifts predicted for bat communities in drought-risk areas of the Northern Hemisphere

Abstract Species occupying semi-arid and dry regions around the globe face an uncertain future due to increases in the frequency and severity of droughts. In this study we modelled the potential effect of climate change on bat communities within two high-drought risk regions of the world and assessed the magnitude and direction of the predicted shifts in climatic suitability, locating climate change refugia and identifying species at greatest risk of population declines. To do this, we compared climate suitability models for 43 species using three global climate models and three emissions scenarios for current (1950–2000) and future (2061–2080) climates within two regions where droughts are predicted to increase, the Western Palaearctic and Western North America. Our models predicted an overall reduction in bat richness with future climates. Areas projected to support high species richness in the current climate coincided with greatest predicted species loss and greatest future drought risk. For species with the potential to extend their range, high velocity range shifts would be required to keep pace with these changes, particularly in the Western Palaearctic, where additional barriers to movement include seas and areas of high human population density. Predicted refugial zones were limited and occurred in similar areas across continents (montane and high latitude with some coastal areas). The area of climate suitability was predicted to contract for around half of study species, with nine identified as species of conservation concern due to low overlap between current and future modelled ranges. The best-case scenario for bat diversity in semi-arid and dry regions in the future is likely to be reduced species richness, with many species facing rapid range expansion over challenging landscapes to access climatically suitable areas. Conservation of bats in high drought risk regions will likely depend on protection of identified refugia and networks of water sources, as well as global measures to protect biodiversity and human wellbeing, such as reduction in global carbon emissions

Sociality, density-dependence and microclimates determine the persistence of populations uffereing from a novel fungal disease, white nose syndrome

Abstract Disease has caused striking declines in wildlife and threatens numerous species with extinction. Theory suggests that the ecology and density-dependence of transmission dynamics can determine the probability of disease-caused extinction, but few empirical studies have simultaneously examined multiple factors influencing disease impact. We show, in hibernating bats infected with Geomyces destructans, that impacts of disease on solitary species were lower in smaller populations, whereas in socially gregarious species declines were equally severe in populations spanning four orders of magnitude. However, as these gregarious species declined, we observed decreases in social group size that reduced the likelihood of extinction. In addition, disease impacts in these species increased with humidity and temperature such that the coldest and driest roosts provided initial refuge from disease. These results expand our theoretical framework and provide an empirical basis for determining which host species are likely to be driven extinct while management action is still possible

Bat Response to Differing Fire Severity in Mixed-Conifer Forest California, USA

Abstract Wildlife response to natural disturbances such as fire is of conservation concern to managers, policy makers, and scientists, yet information is scant beyond a few well-studied groups (e.g., birds, small mammals). We examined the effects of wildfire severity on bats, a taxon of high conservation concern, at both the stand (,1 ha) and landscape scale in response to the 2002 McNally fire in the Sierra Nevada region of California, USA. One year after fire, we conducted surveys of echolocation activity at 14 survey locations, stratified in riparian and upland habitat, in mixed-conifer forest habitats spanning three levels of burn severity: unburned, moderate, and high. Bat activity in burned areas was either equivalent or higher than in unburned stands for all six phonic groups measured, with four groups having significantly greater activity in at least one burn severity level. Evidence of differentiation between fire severities was observed with some Myotis species having higher levels of activity in stands of high-severity burn. Larger-bodied bats, typically adapted to more open habitat, showed no response to fire. We found differential use of riparian and upland habitats among the phonic groups, yet no interaction of habitat type by fire severity was found. Extent of high-severity fire damage in the landscape had no effect on activity of bats in unburned sites suggesting no landscape effect of fire on foraging site selection and emphasizing stand-scale conditions driving bat activity. Results from this fire in mixed-conifer forests of California suggest that bats are resilient to landscapescale fire and that some species are preferentially selecting burned areas for foraging, perhaps facilitated by reduced clutter and increased post-fire availability of prey and roosts

Climate and Weather Impact Timing of Emergence of Bats

We thank two anonymous reviewers for helpful comments on the manuscript and Barry Nickel for advice on statistical analysis. We thank the National Severe Storms Laboratory for radar data processing and access, in particular Brian Kaney and Katherine Willingham. We thank Danny Scipión and Sarah Stough for help with data preparation.Conceived and designed the experiments: WFF THK JFK KWH PBC. Performed the experiments: WFF PMS PBC. Analyzed the data: WFF. Contributed reagents/materials/analysis tools: KWH CMK. Wrote the paper: WFF PMS JFK PBC.Interest in forecasting impacts of climate change have heightened attention in recent decades to how animals respond to variation in climate and weather patterns. One difficulty in determining animal response to climate variation is lack of long-term datasets that record animal behaviors over decadal scales. We used radar observations from the national NEXRAD network of Doppler weather radars to measure how group behavior in a colonially-roosting bat species responded to annual variation in climate and daily variation in weather over the past 11 years. Brazilian free-tailed bats (Tadarida brasiliensis) form dense aggregations in cave roosts in Texas. These bats emerge from caves daily to forage at high altitudes, which makes them detectable with Doppler weather radars. Timing of emergence in bats is often viewed as an adaptive trade-off between emerging early and risking predation or increased competition and emerging late which restricts foraging opportunities. We used timing of emergence from five maternity colonies of Brazilian free-tailed bats in south-central Texas during the peak lactation period (15 June–15 July) to determine whether emergence behavior was associated with summer drought conditions and daily temperatures. Bats emerged significantly earlier during years with extreme drought conditions than during moist years. Bats emerged later on days with high surface temperatures in both dry and moist years, but there was no relationship between surface temperatures and timing of emergence in summers with normal moisture levels. We conclude that emergence behavior is a flexible animal response to climate and weather conditions and may be a useful indicator for monitoring animal response to long-term shifts in climate.Yeshttp://www.plosone.org/static/editorial#pee

Context-dependent conservation responses to emerging wildlife diseases

Emerging infectious diseases pose an important threat to wildlife. While established protocols exist for combating outbreaks of human and agricultural pathogens, appropriate management actions before, during, and after the invasion of wildlife pathogens have not been developed. We describe stage-specific goals and management actions that minimize disease impacts on wildlife, and the research required to implement them. Before pathogen arrival, reducing the probability of introduction through quarantine and trade restrictions is key because prevention is more cost effective than subsequent responses. On the invasion front, the main goals are limiting pathogen spread and preventing establishment. In locations experiencing an epidemic, management should focus on reducing transmission and disease, and promoting the development of resistance or tolerance. Finally, if pathogen and host populations reach a stable stage, then recovery of host populations in the face of new threats is paramount. Successful management of wildlife disease requires risk-taking, rapid implementation, and an adaptive approach."Funding was provided by the US National Science Foundation (grants EF-0914866, DGE-0741448, DEB-1115069, DEB-1336290) and the National Institutes of Health (grant 1R010AI090159)."https://esajournals.onlinelibrary.wiley.com/doi/abs/10.1890/14024

Moving Beyond Too Little, Too Late: Managing Emerging Infectious Diseases in Wild Populations Requires International Policy and Partnerships

No Full Tex

Possibility for reverse zoonotic transmission of SARS-CoV-2 to free-ranging wildlife: a case study of bats

The COVID-19 pandemic highlights the substantial public health, economic, and societal consequences of virus spillover from a wildlife reservoir. Widespread human transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) also presents a new set of challenges when considering viral spillover from people to naïve wildlife and other animal populations. The establishment of new wildlife reservoirs for SARS-CoV-2 would further complicate public health control measures and could lead to wildlife health and conservation impacts. Given the likely bat origin of SARS-CoV-2 and related beta-coronaviruses (β-CoVs), free-ranging bats are a key group of concern for spillover from humans back to wildlife. Here, we review the diversity and natural host range of β-CoVs in bats and examine the risk of humans inadvertently infecting free-ranging bats with SARS-CoV-2. Our review of the global distribution and host range of β-CoV evolutionary lineages suggests that 40+ species of temperate-zone North American bats could be immunologically naïve and susceptible to infection by SARS-CoV-2. We highlight an urgent need to proactively connect the wellbeing of human and wildlife health during the current pandemic and to implement new tools to continue wildlife research while avoiding potentially severe health and conservation impacts of SARS-CoV-2 "spilling back" into free-ranging bat populations

Possibility for reverse zoonotic transmission of SARS-CoV-2 to free-ranging wildlife: a case study of bats

The COVID-19 pandemic highlights the substantial public health, economic, and societal consequences of virus spillover from a wildlife reservoir. Widespread human transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) also presents a new set of challenges when considering viral spillover from people to naïve wildlife and other animal populations. The establishment of new wildlife reservoirs for SARS-CoV-2 would further complicate public health control measures and could lead to wildlife health and conservation impacts. Given the likely bat origin of SARS-CoV-2 and related beta-coronaviruses (β-CoVs), free-ranging bats are a key group of concern for spillover from humans back to wildlife. Here, we review the diversity and natural host range of β-CoVs in bats and examine the risk of humans inadvertently infecting free-ranging bats with SARS-CoV-2. Our review of the global distribution and host range of β-CoV evolutionary lineages suggests that 40+ species of temperate-zone North American bats could be immunologically naïve and susceptible to infection by SARS-CoV-2. We highlight an urgent need to proactively connect the wellbeing of human and wildlife health during the current pandemic and to implement new tools to continue wildlife research while avoiding potentially severe health and conservation impacts of SARS-CoV-2 "spilling back" into free-ranging bat populations

Ecological Energetics of an Abundant Aerial Insectivore, the Purple Martin

We thank T. Fagin for help with estimating the seasonal range area occupied by Purple Martins. We thank an anonymous reviewer, Mark Brigham, and J Boyles for their comments on this manuscript.Conceived and designed the experiments: JFK ESB WFF PBC. Performed the experiments: JFK PBC. Analyzed the data: JFK PBC. Wrote the manuscript: JFK ESB WFF PBC. Developed the model in Matlab: JFK PBC.The atmospheric boundary layer and lower free atmosphere, or aerosphere, is increasingly important for human transportation, communication, environmental monitoring, and energy production. The impacts of anthropogenic encroachment into aerial habitats are not well understood. Insectivorous birds and bats are inherently valuable components of biodiversity and play an integral role in aerial trophic dynamics. Many of these insectivores are experiencing range-wide population declines. As a first step toward gaging the potential impacts of these declines on the aerosphere’s trophic system, estimates of the biomass and energy consumed by aerial insectivores are needed. We developed a suite of energetics models for one of the largest and most common avian aerial insectivores in North America, the Purple Martin (Progne subis). The base model estimated that Purple Martins consumed 412 (± 104) billion insects*y-1 with a biomass of 115,860 (± 29,192) metric tonnes*y-1. During the breeding season Purple Martins consume 10.3 (+ 3.0) kg of prey biomass per km3 of aerial habitat, equal to about 36,000 individual insects*km-3. Based on these calculations, the cumulative seasonal consumption of insects*km-3 is greater in North America during the breeding season than during other phases of the annual cycle, however the maximum daily insect consumption*km-3 occurs during fall migration. This analysis provides the first range-wide quantitative estimate of the magnitude of the trophic impact of this large and common aerial insectivore. Future studies could use a similar modeling approach to estimate impacts of the entire guild of aerial insectivores at a variety of temporal and spatial scales. These analyses would inform our understanding of the impact of population declines among aerial insectivores on the aerosphere’s trophic dynamics.Yeshttp://www.plosone.org/static/editorial#pee