How hot do nest boxes get in the tropics? A study of nest boxes for the endangered mahogany glider

Abstract

As hollow-bearing trees become scarcer due to habitat loss, the use of nest boxes as a management tool for hollow-dependent species is likely to increase. However, nest-box use can be variable among species and habitats, and one possible reason may be that nest boxes offer little protection against extreme temperatures compared with natural hollows; this may be particularly important in the tropics. Here, we measured the microclimate of 16 nest boxes, installed as part of a recovery program for an endangered arboreal marsupial, the mahogany glider, during the summer in tropical north Queensland. We also measured the microclimate of 14 naturally occurring refuges (hollows in standing and fallen trees) at the same study sites. Nest boxes were significantly hotter during the day than were natural refuges (either in fallen or standing live trees) and experienced a greater range of temperatures. The most important factors explaining variation in daytime temperature in boxes was box aspect and the amount of canopy cover directly above the box: boxes that faced north, and those with greater canopy cover, were up to 7°C cooler than those that faced south or had little cover. We discuss our results in relation to the use of nest boxes in management plans for arboreal marsupials in the tropics.