Evolution of Bird Bills: Birds Reduce Their 'Heating Bills' in Cold Climates
Thursday, June 24 2010 @ 10:57 AM EDT
Contributed by: jkr
The size and shape of these distinctive structures are usually explained by their role in feeding and mate attraction. However, previous research shows bird bills have a third, less appreciated function, as organs of heat exchange.
Dr Glenn Tattersall says we know, from our thermal imaging studies that birds like toucans and geese can lose a large amount of their body heat through their bills.
"Unlike humans they don't sweat but can use their bills to help reduce their body temperature if they overheat."
"We then wondered whether this function had evolutionary consequences, and sought to compare bill sizes across a whole range of species," says Dr Tattersall.
The 214 species examined comprised diverse groups including toucans, African barbets and tinkerbirds, Australian parrots, grass finches, Canadian gamebirds, penguins, gulls and terns.
"Across all species, there were strong links between bill length and both latitude, altitude and environmental temperature," Dr Matt Symonds says. "Species that have to deal with colder temperatures have smaller bills."
"This suggests that there is an evolutionary connection between the size of the birds' bills and their role in heat management," he says.
More to the article: www.sciencedaily.com/releases/2010/06/100623104428.htm