EFFECTS OF DEWATERING GALLINACEOUS GUZZLERS ON WILDLIFE.
|Neal W Darby; Mojave National Preserve; firstname.lastname@example.org; Misumi B. Ogawa, Aren N. Calton, Carrie Gonzalas, Michael L. Morrison, Debra Hughson
Gallinaceous Guzzlers were widely established across the southwest beginning in the 1940s. Many of these structures still function but, degradation overtime and changes in jurisdictions and laws have complicated their management. For example, newly designated wilderness dictates their removal due to prohibited human structures. We implemented a Before/After Control Impact study to evaluate wildlife response to the loss of water from these guzzlers given the potential for removal. A subset of 14 guzzlers greater than 3.2 km from any other know water source were selected for monitoring. Seven were later selected for drainage of water (dewatering). Wildlife was monitored at the guzzlers using trail cameras and acoustic bat and bird recorders. Preliminary results suggest bats do not focus on guzzlers and were not affected by dewatering based on echolocation call detections. Of some 16 bird species detected on recorders at guzzlers, about half were detected on trial cameras at the guzzler mouth at regular intervals. Dewatering led to many birds that regularly visited the guzzler abandoning use of the guzzler. We are finalizing results of bird recordings taken after dewatering. Guzzlers likely benefit some species, but greater demographic data is needed to ascertain impacts of dewatering.
DYNAMIC CHANGES IN SPECIES RICHNESS AND COLONY SIZES OF BATS ROOSTING IN ABANDONED MINES SUGGEST USE AS REFUGIA FROM CHALLENGING CLIMATIC CONDITIONS
|Rick E Sherwin; Dept. of Organismal & Env. Biology, Christopher Newport Univ; email@example.com; Jason W. Williams
Southern Nevada has a long history of underground mining and hundreds of abandoned mines remain throughout the region. We have been surveying and actively monitoring bat use of roughly 350 abandoned mines throughout the region since 2006. Over that time, patterns of roost use have been stable with species composition and colony sizes remaining predicable over time. Beginning in 2021 and continuing through 2022 there has been a notable increase in species richness and intensity of use in these features. These changes correlate with drought and heightened surface temperatures throughout the region. Subterranean temperatures have remained consistent despite increased surface temperatures and our findings suggest that mine workings are providing refugia to species that have historically roosted in epigeic features that provide less buffer from changes in ambient conditions.
INFLUENCE OF INTRODUCED TROUT ON FORAGING BATS IN THE SIERRA NEVADA MOUNTAINS
|Dave S Johnston; H. T. Harvey & Associates; firstname.lastname@example.org; Elizabeth Gruenstein
Stocking of trout into naturally fishless lakes in the mountains of western North America has reduced populations of many native species, particularly benthic aquatic invertebrates, in those systems. Although many bats consume emergent aquatic insects, no previously published studies have focused on how bats could be affected by changes to prey populations at lakes subsequent to trout stocking. The aim of this study was to determine whether fishless lakes or lakes stocked with trout provide higher quality foraging habitat for bats. We recorded and analyzed bat echolocation calls to assess overall bat activity, foraging activity, and foraging rates at nine feature-matched pairs of stocked and unstocked high elevation lakes in the central Sierra Nevada of California. Bats that echolocate around 40 kHz showed higher levels of overall activity, foraging activity, and foraging rates at stocked lakes. These higher activity levels could indicate the presence of higher quality foraging habitat. Alternatively, these bats could be foraging on suboptimal prey, pursuing small insects such as mosquitoes, and this could represent a cost to these bats due to the lower energetic return of small prey. Introduced trout may constitute a conservation issue to populations of bats in areas where both taxa occur.
BATS IN SWALLOW NESTS: IMPLICATIONS FOR BAT CONSERVATION
|Jill M Carpenter; LSA; email@example.com; Holly J. Smith, Justin S. Stevenson
While bats have anecdotally been reported roosting in cliff swallow (Petrochelidon pyrrhonota) and barn swallow (Hirundo rustica) mud-nests for several decades, this roosting behavior is rarely discussed in the available peer-reviewed literature. The authors have documented seven bat species roosting in swallow mud-nests in California, Arizona, and New Mexico. Roosting bats have been observed inside swallow nests during the fall and winter seasons, and emerging from swallow nests during the spring and summer, indicating year-round use. The number of individual bats observed roosting in a single nest ranges from one to up to seven, and bats have been found roosting in up to 20-25 percent of nests at a single structure containing swallow mud-nests. At some sites, bat guano indicating use by bats has been observed in almost every swallow nest inspected. Bats can be injured or killed during the removal of swallow mud-nests from structures. Given the extent of use by bats outside of the bird nesting season coupled with the widespread practice of removing swallow nests during that time of year, swallow mud-nest removal could have conservation implications for bats. Recommended best practices to minimize the potential for bat injury and mortality will be discussed.
DETERMINING NIGHTLY MOVEMENTS OF BATS TO CONSERVE FORAGING HABITAT
|Patricia E Brown; Brown-Berry Biological Consulting; firstname.lastname@example.org; William E. Rainey
Knowledge of roosting and foraging requirements is necessary in managing for viable bat populations, especially when areas are being cleared of native vegetation for development, such as solar installations, infrastructure, agriculture, and urban expansion. Bats are very mobile and often active in areas not accessible by roads. Nocturnal aerial tracking from a light aircraft has been successful in determining foraging habitat and the minimum distance traveled for three species of bats: California leaf-nosed bat (Macrotus californicus), Townsend’s big-eared bat (Corynorhinus townsendii) and Allen’s big-eared bat (Idionycteris phyllotis). Macrotus was tracked from three different mine roosts along the Lower Colorado River in winter and summer 2015-16 and exhibited different seasonal activity and foraging behavior. In a summer roost in the same area in 2016, Corynorhinus used the same foraging habitat as Macrotus, with both species traveling a minimum of 40 km/night. In 2004, Idionycteris in Arizona traveled approximately 80 km roundtrip nightly between the roost in creosote bush scrub at 1000 m elevation and foraging areas in mesquite grassland and pinyon/juniper woodland (1500-2000 m) in the next mountain range to the east. Protecting a limited radius of habitats near the roost for foraging would not have been appropriate for these bat species.