Using mounting, orientation, and design to improve bat box thermodynamics in a northern temperate environment

Abstract

Wildlife managers design artificial structures, such as bird houses and bat boxes, to provide alternative nesting and roosting sites that aid wildlife conservation. However, artificial structures for wildlife may not be equally efficient at all sites due to varying climate or habitat characteristics influencing thermal properties. For example, bat boxes are a popular measure employed to provide compensatory or supplementary roost sites for bats and educate the public. Yet, bat boxes are often thermally unstable or too cold to fulfill reproductive females needs in northern temperate environments. To help improve the thermodynamics of bat boxes, we tested the effect of (1) three mountings, (2) four orientations, and (3) twelve bat box designs on the internal temperature of bat boxes. We recorded temperatures in bat boxes across a climate gradient at seven sites in Quebec, Canada. Bat boxes mounted on buildings had warmer microclimates at night than those on poles and those facing east warmed sooner in the morning than those facing west or south. Our best new model based on passive solar architecture (Ncube PH1) increased the time in the optimal temperature range (22–40 °C) of targeted species by up to 13% compared to the most commonly used model (Classic 4-chamber) when mounted on a building with an east orientation (other designs presented in the Supplementary Information). Based on bioenergetic models, we estimated that bats saved up to 8% of their daily energy using the Ncube PH1 compared to the Classic 4-chamber when mounted on a building with an east orientation. We demonstrate that the use of energy-saving concepts from architecture can improve the thermal performance of bat boxes and potentially other wildlife structures as well.

Nest orientation and proximity to snow patches are important for nest site selection of a cavity breeder at high elevation

“…Yet, this temperature effect still ought to be demonstrated for snowfinch nest sites as we did not measure microclimate inside the nest cavities. Especially, it remains unclear if the temperature effect would hold true for all types of nests (rocks, pylons and buildings) as the temperature inertia might vary considerably among them (Grüebler et al 2014, Maziarz et al 2017, Larson et al 2018, Fontaine et al 2021).…”

Experimental nest cooling reveals dramatic effects of heatwaves on reproduction in a Mediterranean bird of prey

“…Clearly, our findings strongly support the idea that nest box design, material, and positioning can be key factors in determining the effectiveness of conservation interventions and in improving the resilience of target species in the face of rapidly changing climatic conditions (Catry et al, 2011). More broadly, incorporating energy‐saving concepts from architecture in the design of wildlife‐dedicated structures can considerably improve their thermal performance and hence the success of conservation efforts under global warming scenarios (Fontaine et al, 2021). In urban settings, integrating such structures with innovative and biodiversity‐friendly architectural solutions (such as green roofs; Fernández Cañero & González Redondo, 2010) could further boost their ecological and conservation value.…”

Home is where the heat is: Thermoregulation of European bats inhabiting artificial roosts and the threat of heat waves

“…This will allow for active roost selection by bats (Kerth et al, 2001;Ruczyński, 2006) and roost switching when necessary (Ellison et al, 2007;Patriquin et al, 2016). This variation is critical to ensure there are suitable microclimates for individuals during post-hibernation or migration, for maternity colonies, and to prevent them from becoming death traps during heat waves (Bideguren et al, 2019;Flaquer et al, 2014;Fontaine et al, 2021;Griffiths, 2021). These recommendations are of particular importance to conservation managers in the hotter and dryer regions of these species' range where heat-related mortality is already being observed (Alcalde et al, 2017;Flaquer et al, 2014).…”

“…However, bat boxes can become hotter than natural roosts, sometimes exceeding normothermic T b (Bideguren et al, 2019;Crawford & O'Keefe, 2021;Flaquer et al, 2014;Lourenço & Palmeirim, 2004), and individuals have been observed abandoning boxes at T roost > 40°C (Flaquer et al, 2014;Lourenço & Palmeirim, 2004). Several recent studies warn that bat boxes are at risk of overheating and that this conservation practice may be an ecological trap for bats (Crawford & O'Keefe, 2021;Crawford et al, 2022;Flaquer et al, 2014;Fontaine et al, 2021;Griffiths, 2021); however, none have measured the heat tolerance or evaporative water requirements of their occupants to quantify that risk.…”