Two Eurasian Blue Tits Cyanistes caeruleus roosting together in a nest-box on multiple winter nights
BIRDS THAT SPEND the winter in a harsh and cold climate face a suite of challenges that require optimization of energy expenditure and energy intake. Some birds roost communally, which can increase energy savings during cold winter nights. However, this behaviour is almost completely absent in chickadees, tits, and titmice (Paridae) as there are very few accounts in the literature of parids roosti