Action Synopsis: Bat Conservation About Actions

Provide alternative bat roosts during maintenance work at road/railway bridges and culverts

How is the evidence assessed?
  • Effectiveness
  • Certainty
  • Harms

Study locations

Key messages

  • One study evaluated the effects of providing alternative bat roosts during maintenance work at road bridges. The study was in the USA.




  • Use (1 study): One review in the USA found that bat houses provided as alternative roosts during bridge replacement works were used by fewer Mexican free-tailed bats than the original roost at one site and were not used by bats at all at three sites.

About key messages

Key messages provide a descriptive index to studies we have found that test this intervention.

Studies are not directly comparable or of equal value. When making decisions based on this evidence, you should consider factors such as study size, study design, reported metrics and relevance of the study to your situation, rather than simply counting the number of studies that support a particular interpretation.

Supporting evidence from individual studies

  1. A review in 2017–2018 of case studies at four road bridges in California, USA (Harvey & Associates 2019) found that bat houses provided as alternative roosts during bridge replacement works were used by fewer bats than the original roost or were not used at all.  At one site, seven bat houses built to replace a roost for four years during bridge replacement works were used by fewer Mexican free-tailed bats Tadarida brasiliensis (2,000 bats) than the original roost (40,000 bats). At three other sites, bat houses built to replace roosts used by pallid bats Antrozous pallidus (18 bats), Yuma myotis bats Myotis yumanensis (40–100 bats), and/or Mexican free-tailed bats (994 bats) during bridge replacement works were not used at all. At all four sites, bat houses (or ‘condominiums’) were built as temporary roosts while bats were excluded from their original roosts during bridge replacement works (dates not reported). Counts of bats before and after the works were taken from questionnaires completed by the California Department of Transportation.

    Study and other actions tested
Please cite as:

Berthinussen, A., Richardson O.C. and Altringham J.D. (2021) Bat Conservation: Global Evidence for the Effects of Interventions. Conservation Evidence Series Synopses. University of Cambridge, Cambridge, UK.


Where has this evidence come from?

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Bat Conservation

This Action forms part of the Action Synopsis:

Bat Conservation
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