Geology topics

Dale W. Sparks

Publications and source records attributed to Dale W. Sparks.

3 recordsLinked to original sources

USGS2024

Diet of Myotis ciliolabrum from six sites in the southwestern United States

With bat populations declining in many parts of the world, detailed life history information will be critical for assessing vulnerabilities of bat populations and associated trophic effects. Myotis ciliolabrum (western small-footed bat) is a species of insectivorous bat distributed from the Great Plains to the Pacific Coast and from British Columbia to Central Mexico. The species is spottily distributed within this wider range but is locally abundant in areas containing appropriate rocky habitat. Despite M. ciliolabrum being relatively common, little information is available about its feeding ecology. Earlier studies have suggested that skull morphology can be used to determine whether insectivorous bats select for soft- or hard-bodied prey, but we hypothesized that M. ciliolabrum may feed opportunistically on a variety of insect types. To test this hypothesis, we examined the feeding habits of western small-footed bats captured during 2000–2022 at 6 national parks and 1 national conservation area across the Southwest. Visual analysis of prey remains in guano revealed that western small-footed bats within our study area consumed insects belonging to 7 orders (Lepidoptera, Coleoptera, Hymenoptera, Hemiptera, Neuroptera, Diptera, and Odonata) and 20 families. Diet varied over time and across geographic space, though we observed a general trend in which the orders Lepidoptera, Coleoptera, and Hymenoptera were consumed at the highest volumes. This varied diet indicates opportunistic feeding in which M. ciliolabrum makes use of locally abundant resources.

Colorado, New Mexico, Texas↗

USGS2017

Genetic mark–recapture improves estimates of maternity colony size for Indiana bats

Genetic mark–recapture methods are increasingly being used to estimate demographic parameters in species where traditional techniques are problematic or imprecise. The federally endangered Indiana bat Myotis sodalis has declined dramatically and threats such as white-nose syndrome continue to afflict this species. To date, important demographic information for Indiana bats has been difficult to estimate precisely using traditional techniques such as emergence counts. Successful management and protection of Indiana bats requires better methods to estimate population sizes and survival rates throughout the year, particularly during summer when these bats reproduce and are widely dispersed away from their winter hibernacula. In addition, the familial makeup of maternity colonies is unknown, yet important for understanding local and regional population dynamics. We had four objectives in this study. For the first two objectives we investigated the potential use of DNA from fecal samples (fecal DNA) collected at roosts to obtain genetically based mark–recapture estimates of 1) colony size and 2) survival rates, for an Indiana bat maternity colony in Indianapolis, Indiana. The third objective was to compare our genetically based colony-size estimates with emergence counts conducted at the same roost tree to evaluate the genetic mark–recapture method. Our fourth objective was to use fecal DNA to estimate levels of relatedness among individuals sampled at the roost. In the summer of 2008, we collected fecal pellets and conducted emergence counts at a prominent roost tree during three time periods each lasting 7 or 8 d. We genotyped fecal DNA using five highly polymorphic microsatellite loci to identify individuals and used a robust-design mark–recapture approach to estimate survival rates as well as colony size at the roost tree. Emergence count estimates at the roost tree ranged from 100 to 215, whereas genetic mark–recapture estimates were higher, ranging from 122 to 266 and more precise. Apparent survival was 0.994 (SE = 0.04) between sampling periods suggesting that few bats died or permanently emigrated during the course of the study. Relatedness estimates, r, between all pairs of individuals averaged 0.055 ranging from 0 to 0.779, indicating that most individuals were not closely related. We demonstrate here the promise of using fecal DNA to estimate demographic information for Indiana bats and potentially other bat species.

Journal of Fish and Wildlife Management↗

USGS2012

Capture and reproductive trends in summer bat communities in West Virginia: Assessing the impact of white-nose syndrome

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 dramatic decline in capture rates of little brown Myotis lucifugus , northern long-eared M. septentrionalis , small-footed M. leibii , Indiana M. sodalis , tri-colored Perimyotis subflavus , and hoary Lasiurus cinereus bats after detection of WNS in 2009. For these six species, 2010 capture rates were 10–37% of pre-WNS rates. Conversely, capture rates of big brown bats Eptesicus fuscus increased by 17% in 2010, whereas capture rates of eastern red bats Lasiurus borealis did not change. Together, big brown and eastern red bats were 58% of all 2010 captures but only 11% of pre-WNS captures. Reproductive data from 12,314 bats showed shifts in pregnancy and lactation dates, and an overall narrowing in the windows of time of each reproductive event, for northern-long-eared and little brown bats. Additionally, the proportion of juvenile captures declined in 2010 for these species. In contrast, lactation and pregnancy rates of big brown and eastern red bats, and the proportion of juveniles, were similar to historical patterns. Our results further elucidate the significance of short-term effects and provide a basis to examine long-term consequences of WNS.

Journal of Fish and Wildlife Management↗