Dale W. Sparks

FORAGING HABITAT OF THE INDIANA BAT (MYOTIS SODALIS) AT AN URBAN-RURAL INTERFACE

Abstract We captured 11 Myotis sodalis and radiotracked them to foraging areas near Indianapolis International Airport during summer 2002. A series (3–7) of multiazimuth triangulations was used to obtain an estimate of the location of each bat throughout the night. Compositional analysis was used to compare habitat that bats used to available habitat at 2 spatial scales. At both spatial scales, bats preferentially used woodlands over other available habitats (especially developed habitats). These findings suggest that suburban development may negatively impact M. sodalis by limiting foraging options. Many conservation plans aimed at protecting bats exclusively target roosting sites. Although roost conservation should continue to be central in efforts to protect bats, available foraging habitat also should be considered.

Why the bat did not cross the road

Roadways are nearly ubiquitous parts of the modern landscape, but their impact on bats remain relatively unknown. We studied the influence of vehicular traffic on the behaviour of commuting bats near the Indianapolis International Airport. A previous study at this site documented that Indiana bats (Myotis sodalis) were much more likely to cross roads with low traffic volumes. One potential interpretation of this result is that bats perceive motor vehicles as a threat and exhibit avoidance behaviour whether or not the bats are in immediate danger. To test this hypothesis, we observed 211 cases of bats approaching roads that bisected their commuting routes. Information recorded at the time included the presence or absence of vehicles, the height the bat was flying, whether a bat reversed course prior to crossing the road and if so the distance from the road or vehicle (if present) when it altered its direction, and finally the speed, type and relative level of noise emitted by vehicles. Results revealed that bats were more than twice as likely to reverse course when vehicles were present as opposed to their absence. When automobiles were present 60% of bats exhibited avoidance behaviour, reversing course at an average of 10 m from a vehicle. Conversely, when no automobiles were present, only 32% of bats reversed their course and 68% crossed the road. The height a bat flew, speed of the vehicle, type of vehicle or level of noise emitted by vehicles had no effect on the likelihood of bats reversing course. These data support the hypothesis that bats perceive vehicles as a threat and display anti-predator avoidance behaviour in response to their presence.

Capture and Reproductive Trends in Summer Bat Communities in West Virginia: Assessing the Impact of White-Nose Syndrome

Abstract Although it has been widely documented that populations of cave-roosting bats rapidly decline following the arrival of white-nose syndrome (WNS), longer term reproductive effects are less well-known and essentially unexplored at the community scale. In West Virginia, WNS was first detected in the eastern portion of the state in 2009 and winter mortality was documented in 2009 and 2010. However, quantitative impacts on summer bat communities remained unknown. We compared “historical” (pre-WNS) capture records and reproductive rates from 11,734 bats captured during summer (15 May to 15 August) of 1997–2008 and 1,304 captures during 2010. We predicted that capture rates (number of individuals captured/net-night) would decrease in 2010. We also expected the energetic strain of WNS would cause delayed or reduced reproduction, as denoted by a greater proportion of pregnant or lactating females later in the summer and a lower relative proportion of juvenile captures in the mid–late summer. We found a dr...

Foraging Behavior of Eastern Red Bats (Lasiurus Borealis) at an Urban-rural Interface

ABSTRACT We captured female Lasiurus borealis near the Indianapolis International Airport during summers of 2003 and 2004 and radiotracked them during foraging. We obtained complete foraging data on 13 bats. A series of multi-azimuth (3–7) triangulations was used to estimate the location of each bat throughout the night. Distance based analysis was used to examine habitat use by L. borealis. Lasiurus borealis had both smaller home ranges than previously noted and smaller home ranges than other species at this location. Lasiurus borealis foraged in woodlands and over newly planted tree fields, open water, park and pasture lands more than predicted by randomly generated points and avoided highly urban areas such as commercial lands, gravel pits and transportation corridors.

Diet of the Myotis sodalis (Indiana Bat) at an Urban/Rural Interface

Abstract We conducted a study of the diet of the federally endangered Indiana bat (Myotis sodalis) at an urban/rural interface near Indianapolis International Airport in summer 2004. We used two 1-m2 quadrats covered with window screening to collect guano under a known roost tree. We then examined 20 fecal pellets/week until the bats abandoned the roost (i.e., 13 weeks). The most common orders of insects eaten were: Lepidoptera (35.3% volume, 84.6% frequency), Diptera (27.9%, 73.2%), Coleoptera (16.9%, 62.9%), and Hymenoptera (10.9%, 45.9%). Components of the diet at the ordinal level varied significantly over time. Despite the developed nature of the site, the diet consisted of the same components reported in earlier studies.

Timing of Birth and Estimation of Age of Juvenile Myotis septentrionalis and Myotis lucifugus in West-Central Indiana

Abstract Patterns of growth and development provide information critical for documenting population demographics. Herein we document the reproductive biology for and provide equations that accurately predict the ages of 2 widely sympatric species of bats from central Indiana—the northern myotis (Myotis septentrionalis) and the little brown myotis (Myotis lucifugus). Young of M. septentrionalis were born synchronously (within a 6-day period) and within a narrow size range (mean length of forearm = 12.78 mm, 95% confidence interval [95% CI] = ± 0.52 mm; mass = 1.91 g, 95% CI = ± 0.11 g). Young of M. lucifugus were born during a 42-day period and within a narrow size range (mean length of forearm = 14.26 mm, 95% CI = ± 0.23 mm; mean body mass = 2.19 g, 95% CI = ± 0.08 g). Young of M. septentrionalis were born significantly smaller (t = 4.52, d.f. = 137, P < 0.001) and lighter (t = 2.57, d.f. = 137, P < 0.05) than were young of M. lucifugus. We developed species-specific equations that made it possible to estimate the age of both species of bat to within 1 day. These results indicate that similar-sized and closely related bats grow at comparable rates and provide the 1st detailed information about reproductive biology of M. septentrionalis.

Exploring the “nutrient hot spot” hypothesis at trees used by bats

Abstract Temperate bat species are well-known predators of nocturnal insects; however, their role in forest nutrient cycling is unclear. We tested the “nutrient hot spot” hypothesis, which suggests that colonial bats should create nutrient peaks in and around their roosts via guano deposits. We measured the mass and nitrogen content of guano deposited outside of roosts occupied by maternal colonies of 2 tree-roosting species, Myotis septentrionalis and M. sodalis. We assessed whether these measures were related to date, species, and bat abundance using least-squares regression. We then compared the expected amount of nitrogen deposited over a maternity season to the expected annual amount of nitrogen mineralized by a forest. Mass of guano deposited increased with bat abundance and corresponded to periods of parturition and lactation. Nitrogen mineralization near a large roost of bats can be 380% of that due to decay of leaf litter. Such nutrient peaks could influence patterns of forest vegetation by impac...

DISTURBANCE OF ROOSTING BATS BY WOODPECKERS AND RACCOONS

Abstract Bats that inhabit dead or dying trees may interact with a wide variety of other animals that utilize this same habitat, including potential predators. Herein, we report two interactions between Indiana myotis (Myotis sodalis) and woodpeckers (Red-bellied Woodpeckers, Melanerpes carolinus; and Northern Flickers, Colaptes auratus). We also report attempts by common raccoons (Procyon lotor) to prey upon both Indiana myotis and evening bats (Nycticeius humeralis). These represent the first reported interactions between either woodpeckers or raccoons and tree-roosting bats of either species. If predators such as raccoons are superabundant in small forest fragments, then increased predation from these animals could be an important source of mortality for bats roosting within these habitats.

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.

FOOD HABITS OF NYCTINOMOPS MACROTIS AT A MATERNITY ROOST IN NEW MEXICO, AS INDICATED BY ANALYSIS OF GUANO

Abstract We examined 56 fecal pellets from under a maternity colony of big free-tailed bats (Nyctinomops macrotis) in the Jemez Mountains of northern New Mexico. The most important food items, listed in order of decreasing percent volume, were Cicadellidae, leafhoppers (26.7% volume, 58.9% frequency); Ichneumonidae, Ichneumon wasps (19.3% volume, 35.7% frequency); and Lepidoptera, moths (17.2% volume, 82.1% frequency). Overall, the most important orders as prey consumed, listed by decreasing percent volume, were Homoptera (27.6% volume, 62.5% frequency), Hymenoptera (19.5% volume, 37.5% frequency), Lepidoptera (17.2% volume, 82.1% frequency), Hemiptera (11.7% volume, 37.5% frequency), and Diptera (10.6% volume, 50.0% frequency). Our study documents an unusually varied diet, as previous studies indicated that these bats fed almost exclusively on moths.