The study of bird behavior will never be complete, as there are as many different aspects to this subject as there are species of birds. Certain activities are common to all bird species, but there is also an amazing variety to be observed in the way they go about their lives. These differences are due to the type of food they eat, their size, the predators they have to face, and the terrain in which they live.
In their natural habitats birds usually mate and reproduce during the warmer months of the year, building their nests and caring for their eggs and young until they can fly and fend for themselves. The location and construction of the nest depends on the habitat and size of the bird; looking at British garden birds for example, the smaller songbirds such as finches, tits and sparrows will build nests of grasses and leaves, lined with hair or feathers, safely hidden inside a hedge. Robins, however, build nests of mud right under the eaves of houses, while larger birds such as magpies make nests of twigs high in the trees. Some birds only breed once a year, to coincide with the availability of the best food for the chicks; others like blackbirds will produce two or more clutches of eggs because their food supply is available for a longer period.
All birds take care of their feathers, and replace them completely once a year. Birds of species which carry out a late summer moult hide away until the feathers grow again, as they are vulnerable to predators when unable to fly properly. In contrast, the aerial species such as swifts and swallows, which never land except when nesting, replace their feathers one at a time so their flight capability is not affected. When cleaning their feathers, small birds like sparrows often prefer to bathe in dust, while the larger thrushes and starlings will happily splash about in a shallow stream.
Many birds spend their lives in one area, returning to breed in a familiar hedge or garden, especially when there is a guaranteed food supply. Migratory birds such as swallows, however, will gather late in the year and fly south together to spend the winter in warmer climates, where their preferred food, flying insects, can still be found.
Bird song is the area where there is possibly the most variety, as birds often have different calls for different reason and many can also imitate other sounds, such as mobile phones or car alarms. The melodious song of a blackbird or thrush at dusk is mainly territorial, to warn other birds to keep away from his area; there are warning chirps from small birds to inform their fellows of a nearby danger such as a cat or a predatory bird; and song is also used by males to impress the female birds as part of a courtship routine. Baby birds call incessantly to demand food from their parents, and gathering flocks of migratory birds will create a wall of sound to attract others of their kind, while waterfowl call out to each other in the dark as they fly home to roost.
The food preferred by different birds depends on the size and shape of their bodies. The smaller birds eat fallen seeds from grasses and other plants which they can peck from the ground, and finches in particular have beaks adapted to strip the outer husk from the seeds; aerial species feed exclusively on flying insects, while larger species will eat insects, worms and fruits. The ‘corvid’ group of birds, which includes crows, ravens and magpies, will feed off dead animals, while predatory birds seek out live ones. Most birds, however, will adapt their eating habits to take food from bird tables, and in the colder months the different species combine their efforts and search for food together in mixed flocks.
The diversity of bird behavior, wherever it is observed, makes a fascinating subject for research and will continue to do so, as the birds constantly adapt their lifestyle to suit their changing environment. Their basic needs of food, shelter and the survival of their species can be met in many individual ways, which shows above all that birds are highly capable of learning and adapting from their experiences.
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