The ability to create shelters that provide protection from the environment is widespread among animals. However, in spite of the central role roosts play in the life of bats (Chiroptera), only a few species have developed the ability to make their own refuges, one of them being the Neotropical Lophostoma silvicolum. This bat creates and inhabits cavities in active arboreal nests of the termite Nasutitermes corniger. We measured temperature in cavities inside active and dead termite nests, and in tree holes occupied by closely related bats, to determine whether energetic benefits compensate for the cost of excavating the hard nests. The inside temperatures of active termite nests were very stable and 2.1–2.8 °C warmer than those of the other two potential roost types. The observed temperature difference is estimated to allow euthermic
L. silvicolum to save about 5% of their daily energy expenditure when roosting in active
termite nests instead of dead nests or tree holes. Suitable roosting conditions result from the presence of termites and are independent of nest architecture. Our results indicate that the benefits of higher temperatures may be one of the driving forces promoting the evolution of active roost making in bats.