In the spring and fall, eastern pipistrelle bats roost deep inside caves  They feed at night on flying insects and must leave the cave to catch their prey  Flying insects are much more abundant on warm nights than on cool ones
Researchers found that many more bats leave the caves on warm nights than on cool nights, even though the temperature within the caves where the bats roost remains virtually the same from one night to the next
Eastern pipistrelle bats can detect changes in barometric pressure within the caves that correlate closely with changes in temperature outside the caves.