Birds combat climate change with bigger beaks

Research led by Deakin University has discovered a pattern between increased climatic temperatures and an increase in the size of the beaks of parrot species in southern and eastern Australia, suggesting that the birds have evolved the larger beaks to cope with a changing climate.

Deakin ecologist Dr Matthew Symonds explained that birds use their beaks to keep themselves cool. “Just as an elephant’s ears help to act as a fan to keep the animal cooler, birds can pump blood to their highly vascularised bills, enabling them to lose excess heat when they get hot,” he said.

Following a study which showed that birds in hotter climates had bigger beaks than those in cooler climates, Dr Symonds and his team hypothesised that climate change has driven the evolution of larger bills in birds. They examined 410 bird skins from five species - the mulga parrot, gang-gang cockatoo, red-rumped parrot, Australian king parrot and crimson rosella - collected between 1871 and 2008.

Writing in the Journal of Biogeography, the researchers revealed that four of the five species examined had measurably bigger beaks now than they had in the 19th century. The Australian king parrot was the only species where an increase in beak size was not recorded.

“We found an increase in beak surface area of between 4 and 10%, which may not sound like much, but would actually make a huge difference to the birds’ ability to cool down when they are stressed by heat,” Dr Symonds said. He added that an increase in beak size could impact the birds in more ways than one.

“The beak is so intimately tied to a bird’s lifestyle that climate-related changes in beaks may have further ramifications for other aspects of their biology: what kind of food they eat, how they compete with each other and how they reproduce,” he explained.

Dr Symonds claimed that the research is the first evidence suggesting a link between birds’ beak size and climate change; however, he conceded that “we can’t yet conclusively rule out the effect of other environmental factors, such as changes in habitat or food availability”.

“The next step will be to expand the research to consider a wider range of species from other regions, and with different kinds of beak shapes and lifestyles,” he said.

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