Bat house programs provide artificial roost sites that compensate for natural roost losses from tree removal, building renovation, and white-nose syndrome. Evidence-based design matters.
Bats excluded from buildings during renovation without replacement roost provision lose maternal roost sites that females return to year after year, separating mothers from pups and disrupting breeding success. Individual bats excluded without alternative roost access face exposure and predation in unsuitable locations. Bat house programs that provide appropriate roost alternatives before exclusion is completed significantly reduce individual welfare harm. White-nose syndrome recovery programs using bat houses at sites where natural roosts have been depopulated provide individual welfare benefit in addition to conservation function. Evidence-based design — appropriate size, color, and placement — determines whether bat houses are actually occupied rather than just installed.