The beak is what first drew attention to himself in the guise of a Toucan. Disproportionately huge in length, almost half of the torso of the bird), painted in gaudy bright red shades, equally exotic plumage, he has long haunted the researchers.
Despite its size, the beak is not much burden the bird, as it is very light due to air cavities inside: in structure it resembles the cured foam. As a result, the beak of the Toucan weighs "only" 5% of body weight (which in the case of a person similar to 4-pound weights attached to the face). Inside it is a lot of tiny hexagonal tiles that are glued together and located similarly to the shingles on the roof. The width of the tile is equal to the diameter of a human hair (50 μm), thickness is only 1 micrometer. This structure makes the bill is especially durable and at the same time is incredibly easy.
| The interior of the beak of the Toucan - hard "foam",
consisting of bone tissues and membranes paramonotone
| The surface of the Toucan beak is built of layers
keratin plates glued together.
|Photo source: UC San Diego, www.jacobsschool.ucsd.edu|
However, for the same reason, the bill may not serve Toucan for protection from enemies - it for this too easy. If he was as powerful as the beak of a woodpecker or a parrot, Toucan not terrible would be no predators, but then he would not have been able not only to fly, but just to sit was always his least beak into the ground. However, grace flight of the Toucan to boast too: because of the relatively large weight and large beak flies it is quite awkward and prefers short flight planning.
What nature has endowed the Toucan such a huge beak, the science is still, frankly, unknown.
Charles Darwin believed that "toucans can have a huge beak size due to sexual selection, in order to show the other birds of its diverse and vibrant stripes adorn this body". In other words, he believed that huge bright beak can be a means of attracting individuals of the opposite sex. However, this assumption is controversial, as toucans no sexual dimorphism - females and males are equally colored brightly, so the possession of any "architectural excesses" (i.e. features that are not useful for direct survival) they are completely useless (biologically impractical.
Later ornithologists agreed that a long beak need to Toukan to get berries from the tips of thin branches that do not bear a half-kilo weight. Reaching berries, Toucan holds it in its beak through the sawtooth notches on the end of it.
This hypothesis, however, despite its plausibility, in practice, no one checked. There are no studies of how generally toucans strive to get berries from long thin twigs. Meanwhile, it is unclear why then toucans very short neck, although for that purpose, which is credited to the beak of the Toucan, more appropriate would be a combination with a long neck. In addition, if the far berry this bill to get easier, the food that is right under your nose, pick up is much more difficult - it needs to move away from it! What kind of expediency!
Recent studies have shown that the beak of the Toucan has another important function: due to the fact that he was abundantly supplied with blood vessels, tucany bill is to regulate heat transfer birds in the hot tropical climate, helping to cool the body. The beak of the Toucan is not just passively emits heat: Toucan able to regulate blood flow to the beak. The effect is particularly noticeable at sunset, when toucans in a few minutes "dump" heat in the beaks, reducing body temperature during sleep.
Using thermal imaging, the researchers found that the beak of the Toucan plays the role of conditioning or heat sink.
In hot weather or during flight bill heats up quickly and gives off heat, preventing overheating birds.
In such moments it takes to 100% Tepa coming from the body. In the cold period in the bill receives only 5% of the heat from the body.
However, the authors of this study are wary about the origin of the large-beaked toucans: the hypothesis that toucans got an impressive beak to solve the problems of thermoregulation, looks pretty doubtful. After all, other birds, including tropical, solve the problem of overheating without special bodies-"radiators": they just open the beak and open wings. Moreover, similarly, do toucans! Even more unclear why the toucans were to grow beaks for cooling during flight, if the flyers they APB... despite the fact that the huge size of the beak makes this the flight...
Even less clear is the role of brightly coloured beak, but it is obvious that such a contrast stain unmask the bird, makes it more visible to enemies. Version of some researchers that the bill serves the Toucan to intimidate, not stand up to criticism, as crested eagles, hunting toucans, their beaks did not confuse.
It is clear that despite visible and not yet known to us the benefits, the bill gives Toucan much more inconvenience not only in flight and other movements, but also for power, for which, according to many scientists, it was all part of the plan: after rasklinivanie fruit this bill is not very convenient due to the fact that the amplitude of the movements of this design significantly reduced; even small fruits and berries toucans have to eat in two steps, using skills juggling with each swallowing: first, they take a portion of food with the tip of the beak, and then throw up and swallow on the fly. The classic size of the beak is much more convenient for the capture and purification, and for crushing food.
But despite all these inconveniences, the family of toucans thrives in the wild, and therefore, it is perfectly adapted to the habitat conditions - whether because of, or despite its exotic appearance.