Warm climates boost bird beak size

Birds have smaller beaks in colder climates

source: New Scientist vol 206 no 2767, 3 July 2010 p17

Beak size can be affected by diet, and size may help a bird attract a mate. It is also affected by climate, according to researchers from Ontario, Canada, and Melbourne, Australia. Glen Tattershall and Matthew Symonds have investigated 214 species of birds, relating female beak size to minimum annual temperatures. They calculate that 16% of variations in beak size can be accounted for by temperature, with colder climates associated with smaller bills that reduce heat loss.