There are various classifications of birds, which are based on a variety of characters. One of them is the degree of development of newborn chicks and the features of their further growth. According to this systematization criterion, two large groups are distinguished: brood birds, examples of which will be given in our article, and nesting birds. Let's consider them in more detail.
Nesting and brood birds: main differences
All representatives of this class breed, laying eggs, after incubating them. After a certain time, chicks hatch from the eggs. Brood birds are characterized by the fact that their newborn chicks are almost immediately ready for independent life. The body of the chicks is completely covered in down. It warms and protects the young body from adverse environmental conditions, and especially from sharp daily temperature drops. This allows such birds to leave the nest immediately and not freeze.
The eggs from which brood birds emerge are quite large and contain a large supply of valuable nutrients. The embryo uses them in order to achieve a significant degree of development even in the shell and to switch to an independent life almost immediately after hatching. Females have to incubate eggs for a long time - sometimes more than three weeks. Immediately after hatching, the chicks are able to see and hear well. Their muscular system is fully functioning, which means they move independently. This is extremely important for protection against unexpected predators. After a few hours, the kids already know how to run fast and fly a little. And after a couple of weeks they can independently find food.
Absolutely helpless chicks hatch in nesting birds. They are born with bare skin, plumage, vision and hearing are absent. Examples of nesting birds are sparrows, woodpeckers, cuckoos, pigeons, etc. After birth, they cannot stand on their feet, thermoregulation has not yet been formed. For these reasons, such chicks stay in the nest for some time, needing the care of their parents, who feed and heat them.
Semi-birds
There is an intermediate group, representatives of which combine the features of both nesting and brood birds. For example, chicks of owls are born blind and develop under the supervision of their parents, but are completely covered with plumage. But gulls for a long time remain in the nests, despite the fact that they hatch both sighted and pubescent.
Habitat
Brood birds, representatives of which are quite diverse, are waterfowl or live on land. They do not build their nests high on trees; they are distinguished by their large body size and large mass. Therefore, chickens have the ability to first slightly flush, gradually fully fledging. Floating broods initially have poorly developed wings, most of the time devoting to the formation of swimming skills.
And now let's take a closer look at the main units of this group.
Crane-like
Brood birds include all species of the crane-like order. They are characterized by a long neck and the same beak and legs. Due to the presence of loops in the trachea, they make characteristic sounds resembling a tube. Being broods, cranes build nests directly on the ground. These are large enough birds, up to one and a half meters high. The wingspan can reach two meters. The most common types of this order are gray, steppe and crowned cranes.
