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Globally, caves provide important refugia for bats. The Grand Canyon, more than 400 km (250 mi) long, consists of steep-sided, rocky formations with hundreds to thousands of natural caves. Two of these, Double Bopper and Leandras Caves, are remarkable because of the presence of desiccated bat carcasses, ranging in condition from skeletal to well-preserved animals identifiable to species. Both caves are complex but differ in length and structure. Double Bopper Cave, >60 km (37 mi) long, is variable with narrow passages. Leandras Cave, 24 km (15 mi) long, has wide, open passages. We surveyed both caves, collecting information for 482 specimens. We initially hypothesized that a single catastrophic event caused the deaths of many individuals or that bats died of various causes over a long period. We expected bat communities to differ between caves, since different cave structures would favor different species based on flight maneuverability. Radiocarbon dating of 67 samples found ages ranged from modern to >45,800 cal BP, spanning the Last Glacial Maximum. The dominant bat species in each cave differed, with Townsend’s big-eared bat (Corynorhinus townsendii), a cave obligate, dominant in Double Bopper Cave and silver-haired bat (Lasionycteris noctivagans) dominant in Leandras Cave. Bats continue to use these caves today, as evidenced by the presence of fresh guano. The remarkable evidence of long-term continuous use of these caves by bats illustrates the importance of protection and conservation to provide habitat for them. The caves also provide an unprecedented time machine to study bat communities from the past, understand long-term patterns of habitat use, and prepare for climate change.

The New Mexico Jumping Mouse (Zapus luteus) is a federally endangered granivore active for only 3 to 5 months annually. Knowledge of diet can help guide habitat recovery and yet despite calls for restoration of its riparian habitat, the diet of Z. luteus remains largely unknown. To date, only 8 plant species have been described in the diet—whereas insectivory, mycophagy, and dietary shifts have only been hypothesized. In the late summer, Z. luteus rapidly accumulates fat for a 9-month hibernation and restoration may fail if seasonal variation in the diet is overlooked. We used DNA metabarcoding on fecal DNA (n = 165) to resolve dietary taxa within multiple trophic levels of the diet and investigate monthly patterns of consumption. Seldom studied in metabarcoding frameworks, we also investigated exogenous contamination in Sherman live-capture traps. Potential contamination among feces, pelage, and trap surfaces was detectable but low (median = 0% to 2%), with fecal communities distinct from exogenous sources. The diet of Z. luteus was varied and most frequently (frequency of occurrence) of graminoids, forbs, lepidopterans, dipterids, and false-truffles. For plant foods, dietary diversity increased throughout their season of activity, shifting from sedges and woody vegetation in the early season (June to July) to forbs and grasses in the late season (August to September). Insect consumption was consistently detected throughout the season, whereas mycophagy was more frequently detected in August, when hypogeous fungi are typically more abundant. The breadth of dietary taxa suggests plasticity in resource use, potentially accommodating diverse patterns of seed availability throughout their active period. Shifts in plant consumption may reflect a dietary adaptation to the phenological patterns of their plant communities, a synchrony that might benefit both pre- and post-hibernation survival. Our work substantially improves our understanding of the diet of Z. luteus (241 dietary taxa) and will be useful for guiding habitat recovery. It also offers scalable methods to further investigate the diet under disturbance contexts (e.g. grazing, wildfire, drought). [ABSTRACT FROM AUTHOR]

We examined the potential for urban water sources, specifically golf course ponds, to act as centers for rabies transmission from bats to mesocarnivores in the arid southwestern United States where surface water is often limited. Because residential housing can act as den and roost sites for both mesocarnivores and bats, we also examined the effect of housing density around water sources on activity. Using ultrasonic acoustic recorders to assess bat activity and camera traps to estimate mesocarnivore activity, we compared 14 pairs of wet and dry locations over two years by surveying twice during the summer, once prior to summer monsoons and once during the monsoon season, when surface waters were more available. Number of calls for all bat species combined were greater at wet sites compared to dry sites and calls of two bat species often associated with rabies, big brown bat (Eptesicus fuscus) and silver-haired bat (Lasionycteris noctivagans), were recorded more at wet sites than dry sites in the monsoon season. In both years, raccoons (Procyon lotor) were photographed more often at wet sites while striped skunks (Mephitis mephitis) and gray foxes (Urocyon cinereoargenteus) were less likely to be detected at wet sites. Bat, fox and raccoon activity was not associated with housing density while striped skunks showed a positive correlation. Finally, we examined potential for contact between mesocarnivores and big brown bats, a species implicated in cross-species rabies transmission in our area, by combining call activity of this bat species and photo detections of mesocarnivores during individual hours of the night into a Potential Contact Index (PCI) and found no significant effect of season (pre-monsoon vs. monsoon), species, or treatment (dry versus wet) but did find a significant species by treatment interaction, with raccoon PCI 3–30 times higher at wet sites and no effect on the other two mesocarnivores' PCI. Overall, we found higher activity of bats at urban waters could increase potential for cross-species transmission of rabies from bats to raccoons but not for gray foxes and striped skunks. [ABSTRACT FROM AUTHOR]