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They keep cool with their large bills.

Tufted Puffins regulate their body temperature using their huge beaks, an evolutionary characteristic that may explain their long-distance flight ability.

Researchers from McGill and UC Davis used thermal imaging cameras to assess heat dissipation off the bodies and beaks of wild tufted puffins minutes after flight. In 30 minutes, the puffins’ beaks decreased by 5°C (25°C—20°C), but their backs remained relatively warm. The beak “accounted for 10–18% of total heat exchange despite only 6 percent of the total surface area” of the bird.

Birds with large bills can fly more efficiently.But why did puffins get such a big bill? Kyle Elliott, a professor in McGill’s Department of Natural Resource Sciences, believes it’s because they fly so often. Flying requires a lot of energy from birds. Flying thick-billed murres have an energy expenditure 31 times greater than resting, the greatest ever measured in vertebrates. Elliott, the study’s main author, speculates that some birds have acquired a broad bill to assist them cool down when flying. “The avian bill is a great evolutionary example,” Elliott added.

As an example, the study’s primary author, Hannes Schraft, a former doctorate student in the UC Biology Department, stated that “thick-billed murres (and likely puffins) produce about as much heat as a light bulb when flying.” “Our findings support the concept that body heat regulation shaped some bird beaks. To assist them cool down, the desert hare’s ears grew wider, which we think is an example of exaptation, “Elliott adds.

“We’re unloading excess body heat,” says Schraft, a postdoctoral fellow at UQAM. wanted to know if puffins use their huge beaks to expel heat as they fly.” “We suspected this because prior studies had revealed it in toucans and hornbills, two bird species with huge bills.”

A bird’s feathers keep its body warm, so it can’t regulate its temperature via sweating. Instead, the bill acts as a radiator, similar to how humans sweat on hot summer days. Schraft agrees that this can be confusing. After all, birds often hide their beaks in their feathers to keep warm. Biologists have also found that birds from colder climates have smaller bills. Because tufted puffins reside in Alaska, a smaller bill would have been the most logical evolutionary conclusion. However, opposing demands may explain puffins’ defiance. “During the breeding season, seabirds must fly large distances to feed their chicks,” adds Schraft. “Puffins may have evolved into bigger bills to address this problem.”

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