Longevity - Take longevity for example; birds have a short life, very short one would say, even if not everyone knows it. It is difficult, as is believed, to be able to return to the same place the following year. For example, scholars believe that passerines are unlikely to survive one year of life, as long as they are birds that live a life in the open air, subjected to bad weather, migratory, object of hunting and predation. The affirmation is almost certain given that, thanks to the ringing and the increasingly concrete and intense field studies, the world of birds begins to reveal its first secrets.
It is surprising to discover that longevity is directly proportional to the size of the bird and the egg that originally hosted it. If a common gull is able to live up to 30 years in very exceptional conditions, a finch is not able to exceed 6 years in the same conditions, comfortable and lucky.
The eggs - Even the eggs must be looked at with renewed attention since they are able to tell us so many additional details about the species.
The nesting birds that move away from the nest practically immediately after hatching are able to lay very large eggs if compared to those of the nests that leave "home" in a clear delay. Just take a look at the snipe or cesena egg: the first is much larger than the second. This is because the very young birds who set out early to discover the world need supplementary energy reserves right away.
It is also surprising that the size of the egg is inversely proportional to the size of the bird.
Even the shape of the egg has its own reason; nature leaves nothing to chance and the type of egg is related to the type of nest and conditions in which it will be laid. Pay attention to it: all the eggs that are laid in the hollows of the trees, in the crevices of the rocks are rounded because in principle it is impossible for them to roll, given the positioning. They are also white, since the need for camouflage is practically non-existent.
On the other hand, when the eggs are laid in places where they could fall they are pear-shaped or conical. Being pear-shaped it is practically impossible to roll: in this way the offspring are safe. It should also be noted that the conical shape becomes particularly functional for the accommodation and diffusion of heat.
Finally, the coloring is another detail that should not be underestimated. It is never casual, but always functional to the camouflage of the eggs.
The hatching - Another moment full of surprises is that of the hatching. Not everyone knows it but feathers are very bad conductors of heat for this reason the brooding birds are endowed by nature with two exceptional incubator plates. These are bare areas, devoid of feathers, well supplied by blood vessels, which overheat as necessary during the hatching period. On average during hatching the eggs reach a temperature of 34 degrees. Then there are the great exceptions: the incubator plates of the pheasant, for example, can even reach 39 degrees, guaranteeing a greater heating of the egg in the upper part and less in the lower part.
Growth - After hatching, the growth of the chicks has a really surprising speed and in general it is inverse to the size. To be clear, smaller species grow faster than larger ones.
Even the feathers coloring is very particular. Suffice it to know here that the color of the plumage of the chicks is always different from that of the adults. The reason is very simple: in this way the little ones are not seen as competitors and competitors and do not have to defend themselves immediately from any aggression.