Birds of paradise.
"We found that tropical birds have a slow pace of life which is reflected in how much energy they spend to stay alive," says professor Joseph Williams of Ohio State University. "This is the first time this has been confirmed in birds." Williams is co-author, with fellow Ohio State researcher Popko Wiersma, of a study published online in the journal Proceedings of the National Academy of Sciences.
In a unique experiment, researchers mist-netted 69 species of birds in the tropical lowland forests of Gamboa, Panama, and measured their basal metabolic rate when the birds were resting. For the temperate species, the team tracked the BMR of thirteen species of birds living near Columbus, Ohio. The data showed that the tropical species used about eighteen percent less energy to maintain normal bodily functions than the temperate species.
"Lower energy use fits with the life history of these tropical birds, which is different than those living in temperate climates," says Wiersma. Typically, tropical birds live long lives and produce a small number of offspring that develop slowly and mature late in life. Temperate birds follow an opposite pattern; they have shorter lives and produce large numbers of offspring that develop and mature quickly.
Further experiments showed that even species from the same genus or family have different metabolic rates depending on if they live in tropical or temperate areas. The researchers tested bird pairs from both the north and the south and found a similar trend--the tropical dwellers expended thirteen percent less energy at rest than their counterparts from the north.
The next group of birds examined were the neotropical migrants, those birds that live in the tropics part-time and travel to temperate climates in the US and Canada to have their young These birds were in between; they expended more energy than the full-time tropical species in Panama but less than the full-time temperate species in Ohio. "These birds have a tropical lifestyle, even though they come up north to breed," Williams said.
The research team plans to investigate why tropical birds have lower basal metabolic rates than temperate species. As of now, they only have theories. "An advantage of a lower rate is that less energy is spent, and therefore less time needs to be spent on feeding, and feeding is dangerous [because of predation]," explains Wiersma. "It is also hypothesized that spending more energy will shorten life span, due to free radicals that are produced as by-products of energy metabolism."
Perhaps the tropical birds are just smarter than the temperate birds. They've figured out the key to a long life is to take it easy, eat less, and have fewer offspring.
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|Title Annotation:||tropical bird's energy use and metabolism|
|Publication:||Americas (English Edition)|
|Date:||Jul 1, 2008|
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