Tree Selection and Landscape Analysis of Eastern Red Bat Day Roosts

ABSTRACT Declining bat populations and increasing demands on forest resources have prompted researchers to investigate tree roost selection of forest bats. Few studies, however, have investigated different spatial scales and landscape pattern as criteria for selection of tree roosts. In 1999 and 2000, we radiotracked 23 eastern red bats (Lasiurus borealis) to 64 day roosts. Using univariate and multivariate comparisons, we tested roost tree variables with random tree data at 3 circular spatial scales: roost tree, plot, and landscape. We found 15 variables that were entered in a stepwise discriminant analysis to best differentiate between the roost and random samples; 11 (73.3%) were landscape variables measured with a geographic information system. On average (x̄ ± SE), red bats roosted in deciduous trees (42.0 ± 2.1 cm dbh) that were located in plots with more (3.1 ± 0.1 m²) basal area, higher (84.0 ± 1.3) percentage of canopy closure, and lower (27.2 ± 2.2) percentage of groundcover than random plots. At the landscape scale (by percent magnitude), red bat buffers (1,000-m-radius circle) had significantly less development (81.6%), less feeding operations (70.4%), more deciduous (52.9%) and pine forest (63.8%), and fewer local roads (5.4%) but more trails (94.1%), open water (61.4%), wetland areas (80.4%), and stream areas (63.1%) than random buffers. Red bat roost trees were significantly closer (χ² = 22.0088, df = 1, P < 0.001) to trails (106.2 ± 13.3 m) than to streams (279.4 ± 28.5 m). Our results suggest that red bats in our study area select roosts in mature riparian forests near trails, open water, and wetlands. The high percentage of landscape values in the discriminant analysis lends support to using landscape metrics as an investigative technique of resource selection. We recommend that managers consider landscape factors when protecting red bat day-roost habitat.     

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 (Quercus spp.).     

Patterns of activity and fatality of migratory bats at a wind energy facility in Alberta,Canada

Studying migratory behavior of bats is challenging. Thus, most information regarding their migratory behavior is anecdotal. Recently, however, fatalities of migratory bats at some wind energy facilities across North America have provided the opportunity and impetus to study bat migration at fine spatial and temporal scales. Using acoustic monitoring and carcass searches, we examined temporal and spatial variation in activity levels and fatality rates of bats at a wind energy facility in southern Alberta, Canada. Our goals were to better understand the influence of weather variables and turbine location on the activity and fatality of hoary bats (Lasiurus cinereus) and silver-haired bats (Lasionycteris noctivagans), and to use that understanding to predict variation in fatality rates at wind energy facilities and recommend measures to reduce fatalities. Overall activity of migratory bats and of silver-haired bats increased in low wind speeds and warm ambient temperatures, and was reduced when the wind was from the North or Northeast, whereas hoary bat activity increased with falling barometric pressure. Fatalities of migratory bats in general increased with increased activity of migratory bats, increased moon illumination, and falling barometric pressure and were influenced by the interaction between barometric pressure change and activity. Fatalities of silver-haired bats increased with increased activity, moon illumination, and winds from the south-east. Hoary bat fatalities increased with falling barometric pressure. Our results indicate that both the activity and fatality of migratory bats are affected by weather variables, but that species differ in their responses to environmental conditions. Spatially, fatalities were not influenced by the position of turbines within a turbine row, but were influenced by the location of turbines within the facility. Our findings have implications for our understanding of bat migration and efforts to reduce fatalities at wind energy facilities. To maximize the reduction of bat fatalities, operators of wind energy facilities could incorporate migratory bats' response to environmental variables, such as barometric pressure and fraction of moon illuminated, into their existing mitigation strategies. © 2011 The Wildlife Society.     

Red algal parasites: models for a life history evolution that leaves photosynthesis behind again and again

Many of the most virulent and problematic eukaryotic pathogens have evolved from photosynthetic ancestors, such as apicomplexans, which are responsible for a wide range of diseases including malaria and toxoplasmosis. The primary barrier to understanding the early stages of evolution of these parasites has been the difficulty in finding parasites with closely related free-living lineages with which to make comparisons. Parasites found throughout the florideophyte red algal lineage, however, provide a unique and powerful model to investigate the genetic origins of a parasitic lifestyle. This is because they share a recent common ancestor with an extant free-living red algal species and parasitism has independently arisen over 100 times within this group. Here, we synthesize the relevant hypotheses with respect to how these parasites have proliferated. We also place red algal research in the context of recent developments in understanding the genome evolution of other eukaryotic photosynthesizers turned parasites.