Bat Use of Hollows in California’s Old-Growth Redwood Forests: From DNA to Ecology

Armstrong, Amon J.; Walker, Faith M.; Sobek, Colin J.; Sanville, Cheri J.; Martin, Stephanie L.; Szewczak, Joseph M.

doi:10.3390/ani12212950

Cited by 2 publications

(1 citation statement)

References 51 publications

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“…Aquatic eDNA studies have detected rare and elusive fish ( Weltz et al, 2017 ; Nester et al, 2022 ), amphibians ( Plante et al, 2021 ), birds ( Neice & McRae, 2021 ) and marine mammals ( Ma et al, 2016 ; Juhel et al, 2021 ). Recently, eDNA left on agave flowers in Mexico and Texas ( Walker et al, 2022 ) and in guano deposits in Redwood tree hollows in California ( Armstrong et al, 2022 ) have been used to successfully detect roosting and migrating bats. To these methods we now add airborne eDNA detection of elusive bat species.…”

Section: Discussionmentioning

confidence: 99%

Out of thin air: surveying tropical bat roosts through air sampling of eDNA

Garrett

Watkins

Francis

et al. 2023

PeerJ

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Understanding roosting behaviour is essential to bat conservation and biomonitoring, often providing the most accurate methods of assessing bat population size and health. However, roosts can be challenging to survey, e.g., physically impossible to access or presenting risks for researchers. Disturbance during monitoring can also disrupt natural bat behaviour and present material risks to the population such as disrupting hibernation cycles. One solution to this is the use of non-invasive monitoring approaches. Environmental (e)DNA has proven especially effective at detecting rare and elusive species particularly in hard-to-reach locations. It has recently been demonstrated that eDNA from vertebrates is carried in air. When collected in semi-confined spaces, this airborne eDNA can provide remarkably accurate profiles of biodiversity, even in complex tropical communities. In this study, we deploy novel airborne eDNA collection for the first time in a natural setting and use this approach to survey difficult to access potential roosts in the neotropics. Using airborne eDNA, we confirmed the presence of bats in nine out of 12 roosts. The identified species matched previous records of roost use obtained from photographic and live capture methods, thus demonstrating the utility of this approach. We also detected the presence of the white-winged vampire bat (Diaemus youngi) which had never been confirmed in the area but was long suspected based on range maps. In addition to the bats, we detected several non-bat vertebrates, including the big-eared climbing rat (Ototylomys phyllotis), which has previously been observed in and around bat roosts in our study area. We also detected eDNA from other local species known to be in the vicinity. Using airborne eDNA to detect new roosts and monitor known populations, particularly when species turnover is rapid, could maximize efficiency for surveyors while minimizing disturbance to the animals. This study presents the first applied use of airborne eDNA collection for ecological analysis moving beyond proof of concept to demonstrate a clear utility for this technology in the wild.

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Section: Discussionmentioning

confidence: 99%

Out of thin air: surveying tropical bat roosts through air sampling of eDNA

Garrett

Watkins

Francis

et al. 2023

PeerJ

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Microclimatic drivers of winter bat activity in coast redwood forests

Andreozzi,

Merenlender

2024

Journal of Mammalogy

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Bats are among the least well-known mammals, particularly in terms of their behavior and activity patterns during the winter. Here, we use passive acoustic monitoring to overcome some of the challenges inherent in surveying cryptic forest bats during the wet season to quantify overwintering behavior for 11 species in California coast redwood forests under varying microclimates. Because different species are active at different forest heights, we also examined the effect of acoustic detector placement (treetop or ground level). Generalized linear mixed models were used to relate acoustic detection probability for 8 species to daytime and nighttime temperature, relative humidity, water vapor pressure, and detector placement. The results indicate that daytime maximum temperature best explained variation in nightly probability of detection, and temperature threshold at which bats were predicted to be detected varied considerably across species. By using more precise species detection methods, we were able to resolve significant differences in activity patterns between Myotis yumanensis and M. californicus, 2 species with similar acoustic signatures that are often lumped together. Myotis californicus was predicted to have a 50% probability of detection at maximum daytime temperature as low as 12.5 °C, whereas M. yumanensis was not predicted to have 50% detection probability until maximum daytime temperature was at least 22 °C, suggesting that M. californicus spends less time in torpor. Also, monitoring at the top of the canopy revealed 4 migratory species to be present in the ecosystem on significantly more monitoring nights than could be observed using conventional ground-based monitoring methods. Improving winter bat survey methods provides evidence that diverse bat species are more active in redwood forests during the winter than previously documented. This finding suggests that coastal forests could provide important winter bat habitat for both resident and migratory species.

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Bat Use of Hollows in California’s Old-Growth Redwood Forests: From DNA to Ecology

Cited by 2 publications

References 51 publications

Out of thin air: surveying tropical bat roosts through air sampling of eDNA

Out of thin air: surveying tropical bat roosts through air sampling of eDNA

Microclimatic drivers of winter bat activity in coast redwood forests

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