Fluxes of resource subsidy across ecosystems can affect consumer-community dynamics in recipient systems. Bracken Cave is an unusual ecosystem because of the magnitude of allochthonous input of guano that is produced by the largest bat population in the world-a colony of more than 20 million Mexican free-tailed bats (Tadarida brasiliensis). Research on the guano-subsidy ecosystems dynamics of Bracken Cave is limited, but imperative to our understanding and conservation of this extraordinary ecosystem. The objectives of this study are to determine the quantity and quality of guano deposition across seasons and its effect on the macroinvertebrate community and to examine the effect of the cave's habitat characteristics, such as distance from entrances and depth within the guano substrate, on the macroinvertebrate abundance and taxon richness at Bracken Cave. Core samples of guano and macroinvertebrates were collected at increasing distances within the cave on a monthly basis. Guano from the core samples was analyzed with respect to C, N, and P to determine guano quality variations. In addition, pitfall trap sampling was employed to supplement the macroinvertebrate core sampling. An estimated dry weight total of 50,500 kg of guano was deposited on the 3078 m 2 of floor from August 2009 to August 2010, with the highest rate recorded in September 2009 and the lowest in January-March 2010. Variations in guano deposits with respect to seasonality do not have a significant effect on macroinvertebrate abundance and richness. On the other hand, habitat characteristics significantly affected the macroinvertebrate abundance and richness in the cave. Macroinvertebrate abundance decreased with increasing depth within the guano substrate. Carbon concentrations were significantly higher in the top layers of guano, while nitrogen and phosphorous concentrations were not significantly different with respect to guano depth. Results from pitfall-trap sampling indicated that macroinvertebrate richness was significantly higher near cave entrances. This study indicates that the invertebrate community at Bracken Cave was relatively stable and experienced few seasonal fluctuations, but was shaped by the micro-habitat characteristics of distance from entrances and depth within the guano substrate. The bats and the nutrients that they contribute play a central role as productivity donors to the bottom-up dynamics of one of the most unusual cave ecosystems in the world.

Carcasses provide an important resource for assessing the vulnerability of bat species and sexes to threats, but the reliability of sex data derived from the external morphology (sexmorph) of bat carcasses remains uncertain. We used genetic‐based assessment of sex (sexgen) to evaluate the effect of carcass age and searcher identity on sexmorph‐based assessments of eastern red (Lasiurus borealis) and hoary (Lasiurus cinereus) bat carcasses identified by 15 different searchers at a wind‐energy facility. The proportion of carcasses for which sexmorph was unknown increased from 0.11 for those recovered within a day of death, to 0.56 within 2–3 days of death, and to ≥0.82 at ≥4 days after death. The proportion of carcasses for which sexmorph was correct decreased from 0.9 for those recovered within a day of death, to 0.65 within 2–3 days of death, and to 0.25 at ≥4 days after death. The proportion of sexmorph misidentifications of the 108 fresh carcasses (collected within 24 hours of death) varied (0.0–0.43) among searchers. These results suggest that sexmorph‐based assessments should be limited to fresh carcasses. Furthermore, additional training of people who collect and identify bat carcasses from renewable‐energy facilities may improve the accuracy of sexmorph data obtained from carcasses. © 2018 The Wildlife Society.

The impacts of wind energy on bat populations is a growing concern because wind turbine blades can strike and kill bats, and wind turbine development is increasing. We tested the effectiveness of 2 management actions at 2 wind-energy facilities for reducing bat fatalities: curtailing turbine operation when wind speeds were <5.0 m/second and combining curtailment with an acoustic bat deterrent developed by NRG Systems. We measured the effectiveness of the management actions using differences in counts of bat carcasses quantified by daily and twice-per-week standardized carcass searches of cleared plots below turbines, and field trials that estimated searcher efficiency and carcass persistence. We studied turbines located at 2 adjacent wind-energy facilities in northeast Illinois, USA, during fall migration (1 Aug-15 Oct) in 2018. We estimated the effectiveness of each management action using a generalized linear mixed-effects model with several covariates. Curtailment alone reduced overall bat mortality by 42.5% but did not reduce silver-haired bat (Lasionycteris noctivagans) mortality. Overall bat fatality rates were 66.9% lower at curtailed turbines with acoustic deterrents compared to turbines that operated at manufacturer cutin speed. Curtailment and the deterrent reduced bat mortality to varying degrees between species, ranging from 58.1% for eastern red bats (Lasiurus borealis) to 94.4 for big brown bats (Eptesicus fuscus). Hoary (Lasiurus cinereus) and silver-haired bat mortality was reduced by 71.4% and 71.6%, respectively. Our