Over 8500 species of birds are known in the world today. In most of the countries, people are interested in birds to a greater or lesser degree. Apart from scientific studies undertaken by ornithologists in evolution and general biology of birds, the amateur bird-watchers have made important contribution to our knowledge of birdlife. It is not necessary to make scientific observations to be a bird watcher. Bird watching is a good sport. Majority of bird watchers watch birds just because they derive incalculable mental refreshment and joy from this simple pastime.
People, nowadays, are becoming more and more conscious that they can not live a healthy life, independent of their natural environment. Birds, in this context, perform an invaluable function. They warn us, by their health and well-being, of the dangers that threaten us in the environment. Several species of birds have become extinct or miserably dwindled in numbers, as a result of pesticide residues in the environment. This warns us that we too are absorbing all kinds of chemicals into our own bodies, which have unpredictable side effects, fraught with dire consequences to our healthy growth. This warns us that this is high time that we must take effective and concrete action to stop all toxic substances getting into the environment. If we are able to put a halt to this terrible decline, we will have the satisfaction that we are helping ourselves as well as these magnificent winged creatures.
Birds have a remarkable range of behaviour. Many of their habits are exceedingly intricate. For example, nest-building in some species involves a wide range of activities including the choice of a proper site, right materials – often different at different stages in the building operations – and a number of weaving and turning movements. Even young birds breeding for the first time may successfully undertake these activities, and go on to raise a family.
Though much still remains a mystery, we now know a great deal more about the behaviour of birds. A number of behaviour patterns are innate in that the bird is born with the ability to do them. Many of the bird’s activities are learned and perfected during its life. Certain aspects of songs of many birds are inherited. However, all the inherited activities are not perfect, and the bird has to use them time and again in order to master them. Contact with others of its own species certainly helps the bird to perfect them. Hence, many activities may include innate aspects as well as those perfected by practice and copied from other individuals. Watching others of its own species and copying their behaviour is an obvious way in which young birds can learn to cope with their environment. It is very important that young birds learn as quickly as possible which objects are dangerous and which pose no threat. For many species, particularly for smaller ones, the early days after leaving the nest are very important, and the parent’s guidance extremely valuable. Nevertheless, the young birds survive sufficiently well for the species to prosper.
Learning by trial and error and continued practice is also very important. Birds have evolved their complex range of habits in relation to what has proved best for them in their natural surroundings.
Songs: Birds produce songs mainly during periods prior to breeding, when territories are being set up and courtship undertaken. Bird songs are highly characteristic, each species usually having a very distinct song. By singing, a male bird announces his claim to a territory and also endeavours to attract a mate. By and large, song is produced by the males, and not by females of a species.
Warning and Fear: In a number of circumstances, birds give calls to draw the attention of other birds towards an approaching predator so as to enable it to take evasive action. For the vast majority of birds, there is always the threat of danger lurking somewhere. In such a situation, discretion is the better part of valour. Once an enemy is identified, the bird can take appropriate action. If the predator is a mammal, the bird can easily avoid it by staying clear of the ground. If, however, the threat comes from another bird, then it must be avoided in another way. This might entail diving into thick bushes, on to or under water, or trying to outpace it, depending on the species of bird threatened, and the area in which it is. Often such flight is accompanied by alarm calls, warning the neighbouring birds of the threat. Parent birds give alarm calls in order to protect their offspring, and secondly there are occasions when there is safety in numbers, by grouping tightly together the birds may be able to make it difficult for the attacking predator to single out and catch any one individual.Young birds generally learn to recognize many of their enemies from the reactions of their parents. They also learn to recognize and give the calls. Small birds, still in the nest, will crouch and remain silent, when they hear their parents warn of an approaching predator. They learn to do this before they are a week old.
Feeding: For lack of teeth, birds do not chew their food at all. Majority of birds eat their prey whole. Many birds such as Warblers, Thrushes, Finches etc. generally take prey of smaller size, which could be swallowed. Some birds like Ducks and game birds may eat foliage.Feeding, sometimes, becomes dangerous for the birds. While feeding, they run the risk of not noticing the approach of a predator until it is too late. Drinking too is often dangerous. Some birds obtain most of their water from their food, especially the insectivores and the birds of prey, which may hardly need to drink. But other birds need water to drink. In doing so, they expose themselves to predators. This is specially true in drier regions, where birds congregate in large numbers at water holes, which become favourite hunting grounds for birds of prey.
Seeds: A wide variety of birds eat seeds of plants. Amongst the non-passerines, Pigeons, Parakeets and Woodpeckers are the prominent ones. Among the passerines, Tits, Nuthatches and Finches are seed eaters. The bills of these species are specially adapted to deal with seeds, which are generally hard structures, and are difficult to eat. A few of the seed-eating species eat seeds the whole year round. Tits are largely insectivorous during the summer months. Many of the Finches feed their young both insects and seeds. The reason for feeding insects to the young is perhaps that insects are richer in proteins than the seeds are. Secondly, insect food contains large quantities of water, which is necessary for the healthy growth of young birds. Some smaller birds such as Tits and Nuthatches store seeds in crevices in the bark from which they retrieve them later.
Fruits: Fruits are often relatively large in size and, as a result, many of the fruit-eating species have evolved wide bills and gapes, enabling them to swallow the fruits whole. Once swallowed, the soft fruits are easily digested. Fruits are highly digestible, and seeds are not, and so usually pass through the gut undamaged. Birds that eat fruits distribute and spread around seeds, and thus, help in the evolution of fruiting plants.
Insects: Besides small passerine insectivores, a great variety of birds eat insects. Many of these such as Warblers, which have small all-purpose bills, look unspecialized for this purpose. The reasons for this are that many insectivorous species turn to other foods at other times of the year. Some birds such as Tits and Warblers eat fruits but they can not be, for obvious reasons, full-time insectivore in temperate regions. The truly specialized insectivores which live on insects the whole year round, may, broadly, be divided into two categories; (i) the birds, which have stubby bills and huge gapes; and (ii) the birds having long pointed bills. The birds with long pointed bills such as Bee-eaters catch flying insects, and then return to a perch, where they set down to eat their prey. The birds that have stubby bills and broad gapes, such as Nightjars, take large insects. Some birds such as Swifts and Swallows take smaller prey. The birds which feed on aerial insects are, to a great extent, dependent on good supplies the year round. They generally do not change their diet. But most of the birds, that seek their prey in temperate areas, move to spend the winter in tropical climate. Many species of birds, such as Swallows, Bee-eaters and Flycatchers, hawk insects on the wing; whereas Warblers glean insects from the foliage. Tree-creepers and Nuthatches climb up and down the trunk of trees searching for insects hidden behind the bark. The most specialized birds that take insects from the trunks of trees are the Woodpeckers, which drill holes into the burrows of beetle larvae and take out the grubs with their long tongues. The tip of the tongue of these birds is generally barbed or sticky enabling them to grip their prey. Many large birds, such as Rollers, Hoopoes and Hornbills, feed on large insects. Birds of prey too may take insects. Some Falcons and Black kites include a high proportion of insects in their diet.
Omnivores: Many species of birds include a great variety of food in their diet. Some have seasonal variation in their diet; while there are many that take a wide range of food at all the times of the year. The common Starling is an example of such a species. They may live in rural or urban areas; feed on worms in the meadows; and may move to the woods at the end of the nesting season, along with their young to reap the caterpillars. Soon after, they may return to gardens to feed on early soft fruits. Other scavengers such as Kites are good at eating anything available from rubbish dumps to dead animals. All these birds could be called omnivores. There are a number of species that specialize on feeding of nectar. Amongst them, the most striking are tiny brilliantly coloured Hummingbirds, which possess wonderful skill to take nectar from flowers. There are also Sunbirds, which are small but are often brightly coloured. They too hover at flowers to obtain nectar. The White-eyes can roll the tongue into a tube, and suck the nectar into their mouths.Birds, that are wholly dependent on a special diet, may face inherent dangers. If the diet becomes scare or disappears, their very existence is threatened. In such circumstances, some birds, such as Whitebreasted Kingfishers, adapt themselves to take to new form of food, different from their traditional diet.