Bat boxes as roosting habitat in urban centres: ‘thinking outside the box’

Bats in urban environments depend on human-made structures or remnant natural habitats for roosting. Bat boxes are commonly used artificial structures that aim to replace lost tree or building roosts, but they are not a universal solution, or panacea, as few species use them, and other options exist that more closely mimic natural tree cavities. As long-lived mammals, bats may be lured into human-built structures with unstable conditions. These structures could act as ‘ecological traps’ if they suddenly become inaccessible with few other roost options available. Problems arising from the use of bat boxes, such as mortality events resulting from overheating, may reflect limited roost availability rather than inherent flaws in bat box designs. Mimicking a natural roosting area requires accommodating requisite roost switching. This can be accomplished in urban centres by manipulating existing trees or erecting multiple, varied bat boxes in close proximity, which could require purposeful urban planning. Engaging the public in community-driven bat conservation initiatives may hold the key to ensuring bats thrive in human-dominated landscapes. Here, we discuss problems associated with bat boxes and propose solutions, using case studies from Canada and Australia.