Geology topics

Brenna A. Hyzy

Publications and source records attributed to Brenna A. Hyzy.

3 recordsLinked to original sources

USGS2020

Occupancy and detectability of northern long-eared bats in the Lake States Region

The northern long‐eared bat ( Myotis septentrionalis ) is one of the bat species most affected by white‐nose syndrome. Population declines attributed to white‐nose syndrome contributed to the species’ listing as federally threatened under the 1973 Endangered Species Act. Although one of the most abundant Myotine bats in eastern North America prior to white‐nose syndrome, little is known about northern long‐eared bats in the upper Midwest, USA. We assessed the habitat associations of the northern long‐eared bats on a regional scale using occupancy models that accounted for uncertainty in nightly detection to provide needed information on the distribution as white‐nose syndrome has recently arrived in this area. We monitored bat activity using zero‐crossing frequency‐division bat detectors for 10–15 nights at 20 detector sites at each of 3 sampling areas in Michigan, USA, and 6 sampling areas in Wisconsin, USA, stratified by mesic and xeric habitat types. We constructed northern long‐eared bat nightly detection histories for our occupancy analysis using maximum likelihood estimates from 2 commercially‐available automated identification programs: Kaleidoscope and Echoclass. We sampled for a total of 2,174 detector‐nights. Both Kaleidoscope and Echoclass identified northern long‐eared bat passes on 110 detector‐nights, whereas on 1,968 detector‐nights neither program identified a northern long‐eared bat call. Only one program or the other identified northern long‐eared bat calls on 206 detector‐nights, indicating an overall agreement rate of 35% on nights when calls were detected. We analyzed these data using an occupancy analysis accounting for the potential for false positives to assess the relationship between northern long‐eared bat presence and habitat characteristics. Our analyses indicated that the probability of a false positive at a site was low (0.015; 95% CI 0.009–0.021), and detection probability, but not occupancy, declined from 2015 to 2016 for sites in Wisconsin sampled in both years. Occupancy was positively associated with distance into the forest interior (distance from nearest road).

Michigan, Wisconsin↗

USGS2020

Investigating maternity roost selection by northern long-eared bats at three sites in Wisconsin

One of the North American bat species most impacted by white-nose syndrome (WNS) is the northern long-eared bat Myotis septentrionalis , which as a result has been listed under the Endangered Species Act. WNS was first detected in Wisconsin in 2014. Unfortunately, little is known regarding the ecology of M. septentrionalis in this state pre-WNS to guide management supporting post-WNS recovery efforts. The objectives of our research were to (1) assess characteristics of trees that are associated with roost tree selection and (2) investigate how characteristics of maternity colony networks compare to colonies in the eastern USA. We mist-netted at 3 sites in Wisconsin in 2015 and 2016, and affixed radio transmitters to 39 female M. septentrionalis . We tracked bats to 53 confirmed day roosts. We found that roost trees were larger, more decayed, and more likely to be in dominant canopy closure areas than random trees. Oaks Quercus spp. were used most frequently and in proportion to their availability in the landscape at 2 field sites, whereas invasive black locust Robinia pseudoacacia was used more than expected based on availability at another site. Overall, minimum convex polygon sizes for maternity roosts were variable (5.2 to 8.9 ha) but similar to values reported for other regions. However, network centrality was low, indicating equitable use of day roosts and more frequent roost switching compared to other regions. Our findings provide information that increasing availability of potential day roosts in the landscape during the reproductive period may improve recruitment, which may in turn mitigate some of the detrimental population effects from WNS.

Wisconsin↗

USGS2016

Monitoring the status of Gray Bats (Myotis grisescens in Virginia, 2009-2014, and potential impacts of White-nose Syndrome

Myotis grisescens (Gray Bat) is a federally endangered species distributed over the mid-South with a summer range that extends across the upper Tennessee River Basin, including southwest Virginia. Given the onset of White-nose Syndrome (WNS) in the Commonwealth in the winter of 2009, we initiated yearly surveys in late summer 2009 to monitor the status of known summer populations. Our objectives were to examine the relative health of these bats using body mass index (BMI), and determine any changes in juvenile recruitment across sites and years. We did not find any marked changes in BMI across years after WNS for Gray Bats. This finding suggests that surviving bats are either not negatively impacted by WNS or have recovered sufficiently by late summer as to not document obvious differences across years. After limiting our analyses of juvenile recruitment to only the individuals that we had definitively aged via backlit photos (2010–2014), we found a non-significant declining trend in juvenile recruitment; a trend that merits continued monitoring in the years to come. As Gray Bats have only recently shown to be susceptible to WNS infection, it is possible that observable population declines are forthcoming.

Virginia↗