Birds, without exception, lay eggs, and most of them take care of their offspring. The offspring are taken care of by both parents (when they lay eggs, they take turns or not). Sometimes this is done only by the female (for example in the case of hens), in some cases it is done only by the male (eg foxes). However, there are also birds that do not take care of their offspring after laying eggs. Thus, the common coward works, which lays its eggs in the nests of other birds, primarily in the nests of shrubs, reed warblers, roaches and common bustards. A young coward that usually hatches before the young hosts throw their offspring (eggs and young) out of the nest, because otherwise, when distributing food to all the young, it would have too little food left and it would soon die.
Birds build their nests from a variety of materials, most often covering them with hair or feathers, which they pick up in the vicinity of the nesting place or with feathers plucked from their own body (eg ducks). Falcons and owls are known not to build nests but to lay eggs on the bare ground of rocky shelves, in hollows or in the attics of buildings. Some birds inhabit the abandoned nests of other birds. Owl nests are usually lined with prey remains.
Nests on the ground
they are found on the ground, forest litter, sand, … sometimes they are hidden in the vegetation, among the rocks, sometimes they are outdoors, without shelter. They can be in the form of a shallow depression on the ground (for example in blinds) or solidly built in the shape of a coupe (red-beaked swan);
they are built of aquatic plants on the water surface, anchored among reeds or woodpeckers, attached to underwater vegetation or to the bottom (small grebes);
Nests in trees
they are usually in the axils of the branches, right next to the trunk but also at the top of the branch, they are of different shapes, from flat (pigeon grivnjaš) to bowl-shaped (štiglić), we also know ball-shaped nests, which are either free-hanging (white arbor) or trapped between branch (long-tailed tit). This group also includes nests in shrubs as well as nests suspended between herbaceous plants (eg reeds);
Nests in holes
they are located in cavities in trees. Birds that nest in this way are called “hollows” and are divided into two groups: 1 – primary hollows, those that dig their own holes in the tree (eg woodpeckers) and 2 – secondary hollows that inhabit the holes built by primary hollows or those that occur naturally. with the death and decay of the tree core, they often nest in birdhouses (eg forest owl);
Nests in holes – tunnels
they were excavated in clayey or sandy shores and rocks. They can be of different lengths, and the egg chamber is located at the end of the tunnel (eg waterfowl);
Nests on the rocks
usually birds nest on stone shelves (eg gray hawk), in rock crevices (eg common whitefish) or stick the nest on a cliff or in a ditch (eg city swallow)
According to how many chicks remain in the bird’s nest, we divide it into two groups:
- Squatters (nidikolni mladunci) -after sawing they are naked, helpless, often blind and therefore require more caring care; they remain in the nest for a long time after spawning and leave it only when they take off
- Podkorušci (nidifugni mladunci) – already at the time of weaning they are overgrown with down, they leave the nest immediately after weaning and are able, with the supervision and help of adults, to look for food on their own.
The migration of birds is called the flight of birds from the area where they nest in winter habitats and back, which takes place every year. Bird species that migrate in only one part are called partial migrants. Those who do not move are called tenants. The most important ecological reason for the migration of birds is the availability of food and temperature. The migration of birds is always very exhausting and many individuals do not survive it.
Montenegro is located on the Adriatic Migration Corridor, one of the most important migration routes in Europe, and several million birds fly over it every year.
The most beautiful example of migration is the Arctic tern Sterna paradisiaea, which has covered more than 80,000 kilometers from half to half every year, passing through every climate region.