All birds found in present-day Europe are able to fly. Some are capable of rapid and sustained flight: others are clumsier and unable to remain airborne for long. Examples of these indifferent fliers are the gallinaceous birds, such as the capercaillie, pheasant and black grouse, which can get into the air quickly and fly for a short distance when danger threatens.
This class of bird keeps close to its normal territory throughout the year. At the other end of the scale are the predators, birds that are the most skillful and fastest fliers of all, especially members of the Falconidae family. A hobby, for instance, can even catch a swallow or swift in the air, and these last two birds can fly at speeds of up to 160 kilometers per hour. But the hobby is able to attain a speed 20 kilometers per hour in excess of that.
As for the peregrine falcon, plummeting downward to attack its prey with wings pressed close to the body, it can reach a speed of up to 280 kilometers per hour. The better fliers are all migratory birds, some of which travel hundreds and even thousands of kilometers each year in transit to and from their winter quarters.
Birds can be divided roughly into three groups according to whether they are migratory or not:
1. Resident birds — that never leave the general area of their nesting grounds, not even in winter.
2. Migratory birds — that leave their nesting grounds each year in late summer or early autumn, fly to warmer quarters for the winter and return again in the spring.
3. Transient migrants — birds that range far afield from their nesting grounds after the breeding season, often hundreds of kilometers.
There may, however, be various transitional stages between these three basic groups and, sometimes, contrary classification for members of one and the same species. For example, peregrine falcon and kestrel which nest in northern Europe are migratory, whereas those of western and central Europe are resident. In other species, some members are migratory (mostly young birds and females) and others resident, namely males, as in the case of the blackbird.
There are also species which, in general, are classed as migratory but some of their members remain in their nesting grounds for the winter; typical of this group are the robin and hedge sparrow. Sometimes, however, birds that are otherwise resident will suddenly set out in large flocks on a long journey south or southwest; these are called invasional migrations.
One example is the Nutcracker, normally a resident or transient migrant, which sometimes, however, travels in large flocks to central Europe from the north or northeast. There are also the birds which became regular winter guests, migrants who have left their breeding grounds in the far north to spend the winter in central or western Europe.
Most birds in Europe migrate in roughly three main directions: from north and northwest across western Europe and the Iberian Peninsula; from the north and central Europe south-ward across Italy and Sicily to northwest Africa; and from northeast Europe across the Balkan Peninsula and Asia Minor.
There may, of course, be deviations from these routes and it is not uncommon for birds of the same species, but different populations, to travel in different directions. Many migratory birds of central Europe travel west or southwest, as a rule, spending the winter no farther afield than southwest Europe or northwest Africa. One such example is the mistle thrush, although individual members inhabiting western and southern Europe remain resident. Redwings from the north winter in western or southern Europe and the wood pigeon is to be found in southwest Europe, France and Spain.
Some European birds fly as far as tropical and southern Africa. This is an almost unbelievable distance of more than ten thousand kilometers, which they travel twice each year, in spring and autumn. Thus we find that the honey buzzard winters in tropical Africa, as do the flycatcher, chiffchaff, and oriole. The nightjar journeys as far as eastern and southern Africa and our old friend the cuckoo has its winter quarters in tropical and southern Africa. South and West Africa is host to the hobby during the winter, whereas its larger relative, the peregrine falcon, journeys no further than western and south, western Europe.
This is true, of course, of individuals from Europe’s northerly regions; peregrine falcons from other parts of Europe are either resident or transient migrants. The autumn migration of falcons begins in October and is a leisurely affair, as is often the case of other migratory birds. Falcons often stop for a few days in towns where pigeons nest in great numbers, attacking them from church towers and other vantage points which serve as their temporary quarters.
Similar winter areas are visited by Europe’s smallest predator of the Falconidae family, the Merlin, which regularly crosses central Europe on its journey from Scandinavia en route to places as far distant as northwest Africa. The honey buzzard makes even longer flights, as far as tropical west Africa, while the rough-legged buzzard, Buteo lagopus, which nests in the far northern tundras, passes the winter in central Europe.
Typical residents are the gallinaceous birds of Europe, with the exception of the quail. Some tits, woodpeckers and owls, especially the horned owl, are mostly resident but may sometimes travel southwest. This is not true migration. Corvine birds are mostly transient migrants. Migratory birds do not make the journey to their winter quarters without a break. This would be an impossible task.
They usually fly about 60 to 100 kilometers a day, though shorebirds hold the record, sometimes covering between 300 to 600 kilometers a day. After a short time to rest and find food they set off again; if the weather is bad, however, they remain for several days in one place. The return passage to the nesting grounds is faster, usually by about a third, for the birds are urged on by the breeding instinct. The average airspeed of a bird on migratory flights is less than that of which it is capable over short distances, as when fleeing from an enemy or attacking prey.
Thus, the rook flies at about 50 kilometers per hour, the finch 52 kilometers and the sparrow up to 70 kilometers. Some migrating birds fly only during the day (swallows and finches), others only at night (warblers and chiffchaffs). There are also those like thrushes and wagtails which show no particular preference and fly by night or day, the actual flying time is limited to only a few hours in each twenty-four.