A team of researchers from the University of Siegen's Institute of Biology in Germany, working with a colleague from Marburg University, also in Germany, has found that common swifts use daily torpor as a means of saving energy during their breeding season. In their paper published in the journal Biology Letters, the group describes their non-invasive study of the migratory birds and what they learned about their ability to save energy during cool nights in Europe during the breeding season.