Passerine birds' survival tactic overturns long-held assumptions

Passerine (perching) birds make up 60% of all bird species, including some familiar Australian favorites, like the superb fairy-wren and willie wagtail. Until now, they were believed to only be capable of shallow reductions in body temperature, with deeper and longer torpor restricted to a few non-passerine bird groups, such as hummingbirds and nightjars. New research reveals that this largest group of bird species can enter deep torpor—a power-saving mode of reduced body temperature and metabolism—overturning a long-held understanding of their limits.