Bats and Mines: Evaluating Townsend's Big-Eared Bat (<i>Corynorhinus townsendii</i>) Maternity Colony Behavioral Response to Gating

Diamond, Gabrielle F.; Diamond, Joel M.

doi:10.3398/064.074.0407

Cited by 8 publications

(9 citation statements)

References 21 publications

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“…Spanjer and Fenton () concluded that higher bat activity and smaller gate size corresponded with an increase in fly‐retreat and circling behaviors. They observed no collisions with gates, whereas Diamond and Diamond () documented such collisions during breeding seasons when crowding resulted in sub‐adults colliding with gates. Unfortunately, the amount of time needed by bats to acclimate and return to pre‐gate behaviors was not well documented, although one long‐term study reported initiation of emergence for gray bat colonies did not differ between gated and ungated sites (Martin et al ).…”

Section: Discussionmentioning

confidence: 99%

“…Gray and Townsend's big‐eared bats were the primary focal species in short‐term studies (Powers , Ludlow and Gore , Martin et al , Diamond and Diamond ), although 10 additional species were also monitored (Table ; Ludlow and Gore , Spanjer and Fenton , DeRusseau and Huntly 2012). Bats changed flight behaviors at standard angle‐iron and round bar gates immediately after installation and increased circle and fly‐retreat and decreased pass through behaviors compared to pre‐gate behaviors (Spanjer and Fenton , DeRusseau and Huntly 2012, Diamond and Diamond ). Spanjer and Fenton () concluded that higher bat activity and smaller gate size corresponded with an increase in fly‐retreat and circling behaviors.…”

Section: Discussionmentioning

confidence: 99%

“…Consequences are not well understood but are thought to affect survival and fitness, particularly if these negative behavioral responses persist long‐term. In addition, changes in the way bats exit or enter sites may increase their risk of predation if they modify flight behavior in a way that increases opportunities for predators (e.g., snakes, raptors) to capture bats as they exit (Speakman et al , Diamond and Diamond ). Changes in behavior that negatively affect use of caves and abandoned mines by bats may make it necessary to re‐evaluate closure methods.…”

Section: Discussionmentioning

confidence: 99%

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Mixed effects of gating subterranean habitat on bats: A review

Tobin

Chambers

2017

J Wildl Manag

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Caves and abandoned mines, roosting environments for many bat species including subterranean obligates, are under human pressure (e.g., recreation) and pose threats to humans. Gating entrances of these subterranean features prevents human entry while protecting habitat for bats. However, bat response to these gates is not well understood and no comprehensive synthesis with species-specific recommendations on protection measures for bat roosts exists. We reviewed literature on effects of gating subterranean habitat on bats and roost microclimate and found 22 studies and reports from North America, Australia, Europe, and Asia. Ten studies examined effects of gating on bat use, 9 described behavioral responses to gates, and 5 presented effects of gates on roost microclimate. Older gate designs , such as cement walls or iron doors, negatively affected bat use and roost microclimate, but responses to modern (1970s to present), bat-compatible gate designs varied. Short-term responses of bats to batcompatible gates were negative and included increases in energetically expensive flight behaviors. Although long-term responses included a mix of population and species trends, we attribute these mixed responses in part to differences in flight agility among species. Bats with moderate to high agility (low wing loading, broad call bandwidths) adjust to gates, but species with low agility (high wing loading and narrow call bandwidths) may abandon sites after gating. Other factors including bat density in roosts and size of the cave or mine entrance also affect acceptance of gates and should be considered in gate design. Current gate designs are adequate for most species. Based on available literature, we recommend use of bat-compatible gates with horizontal bar spacing of 14.6 cm, bar types that offer high structural rigidity in areas where vandalism is likely, and periodic monitoring of gates to ensure they remain in good condition. Ó 2017 The Wildlife Society.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Mixed effects of gating subterranean habitat on bats: A review

Tobin

Chambers

2017

J Wildl Manag

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“…In their center section, ladder gates had vertical bar spacing large enough for bats to fly through but on either side of the gate, grates only allowed for airflow (Navo and Krabacher ). In Utah, round steel or Manganal © bar gates with variable horizontal bar spacing (10 cm for the lower 67% of the gate and 14 cm for the upper portion) were installed at adits (Diamond and Diamond ). Metal corrugated culvert gates, often used at mines with unsound portals or collars (entrances), helped stabilize the entrance (Tuttle and Taylor ).…”

mentioning

confidence: 99%

“…Older gate designs (i.e., >45 yrs ago) that block 1 or part of an entrance often negatively affected bats and microclimates of caves and mines (Richter et al , Kennedy ); however, responses of species to gates designed specifically for bats (bat‐compatible) varied from negative to positive (Tobin and Chambers ). In general, short‐term studies reported that bats increased energetically demanding behaviors such as circling or fly‐retreating when encountering gates (Spanjer and Fenton , Derusseau and Huntly , Diamond and Diamond ). The degree to which these behaviors affected energy budgets of bats was not well understood but thought to be particularly detrimental during periods of high energy demand such as pregnancy or lactation (McLean and Speakman ).…”

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confidence: 99%

Acceptance of bats to gates at abandoned mines

et al. 2018

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Caves and abandoned mines provide roosting habitat for bat species that depend on subterranean conditions. Disturbances at caves (e.g., commercial development, recreation) limit their availability to bats, in some cases shifting use to abandoned mines. However, abandoned mines pose public safety hazards and often are gated to reduce risk to humans while maintaining access to bats. To date there is limited information on species‐specific acceptance of gates at abandoned mines. We designed our research objectives to determine short‐term (1 week) behavioral responses of bats to gating, including gate material and height above ground, mid‐term (<1 yr) changes in bat use before and after gate installation, and long‐term changes (≥4 yrs) in use and factors influencing species presence. We used an in situ mock gate experiment, comparison of bat use before and after gating, and genetic identification of guano in gated mines for our short‐, mid‐, and long‐term studies, respectively. In our short‐term study, bats increased energetically demanding behaviors following gate installation. Although we detected no difference in responses to gate material or height, a less maneuverable bat species circled, collided, and landed more frequently on gates than did an agile species. In the mid‐term study, activity remained stable or increased at 73% of mines after gating compared to before gating, although number of maternity colonies decreased. In the long‐term study, elevation, portal area, number of mine levels, and entrances were more important than gates in predicting presence of 4 bat species, including 2 subterranean obligates. Species‐specific responses to gates appeared based on morphology and vocalization characteristics. Responses to gates shifted from negative in our short‐term study to positive in our long‐term study. Gate age and mine characteristics were more important predictors of use for most species than gate design. Although the complexity of subterranean habitats makes them difficult to replicate and many factors may influence how bats use this habitat, gates designed for bats (bat‐compatible) appear effective for many species. © 2018 The Wildlife Society.

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