Birds beak size depends on the temperature


06/08/2012

Environmentalists have tweaked the classical Darwinian theory according to which the size of a bird’s beak depends on the diet of birds. New observations have shown that the birds beak is a kind of heat sink, so it is half the size determined by the temperature of the environment.

Of course, the shape and size of the bird’s beak is influenced by what it feeds on, but, according to scientists from the Smithsonian Institution, it is not only limited to one meal. A few years ago, Russell Greenberg, one of the environmentalists of this American University, said that singing sparrows that live in saline marshes and lack of fresh water, the bill is more than that of those birds who do not experience water shortages. After this casual observation caught the eye of scientists information on radiation heat toucans: it turns out that 60% of the heat emitted by their bodies, scattered through their giant beak.

On this basis, an ecologist concluded that the beak is important for thermoregulation. However, there was one objection. At the toucan’s beak can be used for thermoregulation, as it has a huge size, but in a tiny sparrow beak heat loss, it would seem, should be negligible. However, it turned out that it is not. U.S. researchers compared the heat loss through the bill in two different populations of sparrows. The surface of the beak in the same population was 17% greater than that of the other. The researchers found that birds with large beaks lose 33% more heat.

Usually birds to cool the body often breathe, but they lose a lot of water. According to scientists, the beak with a lot of blood vessels helps them cool while avoiding excessive evaporation of water.

The researchers also compared the size of the beaks in modern singing sparrows and more than a thousand museum pieces, living in different environmental conditions. It was found that the birds that inhabit the area with a hot climate, often had large beaks. But when the temperature exceeded 37 ? C, then the size of a bird’s beak again began to decline. The researchers attributed this to the fact that the body temperature of birds is about 41 ? C, and therefore the air when heated up to that value beak does not begin to radiate heat, and absorb it. So when it gets really hot, it makes sense to reduce the beak.

According to the materials Sciencemagis.ru


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