Finches

Finches

The finch is of one kind or another and they are familiar to everyone. Not only do they breed commonly in our parks and gardens, but they are also frequent visitors to feeding trays in winter. However, few people are familiar with more than a handful of species.

Finches have stout bills, strong skulls, large jaw muscles, and powerful gizzards, all for coping with hard seeds. Other seed-eating birds share these features, but theFringillidae are distinguished by the presence of y instead of large primary feathers in each wing. 12 large tail feathers, and the fact that the female is responsible for building the cup-shaped nest and for incubating the eggs.

The three species of fringelike finches have fairly long tails, peaked heads, and prominent shoulder patches, and wing markings. Chaffinches breed in all kinds of woodland, and over much of Europe are one of the commonest birds, usually comprising between one-fifth and two-fifths of the total woodland bird population. The brambling replaces the chaffinch as a breeding bird in the subarctic birch woods of northern Europe, and also extends across Asia to Kamchatka, migrating south for the winter, and concentrating in areas with beech masts. The rare Blue chaffinch occurs only in high-altitude pine forests of the Canary Islands.

The fringelike and cardueline finches dif-far in the way they feed their young and the dispersion system that results from this. Although the main food of all species is seeds, fringelike finches feed their young entirely on insects (especially caterpillars), while cardueline finches feed their young either on a mixture of seeds and insects or seeds alone. The raising of young entirely on a seed diet is comparatively rare among birds but has been recorded for crossbills, siskins, redpolls, and linnets. Also, while fringilline finches carry insects to their young one or a few at a time in the bill, car-due line finches carry large quantities of seeds in their gullets and regurgitate them to the young. Some species, including the bullfinch, have special throat pouches for this purpose.

The fringelike finches defend large territories while breeding and pairs spread themselves fairly evenly through the habitat. The food is obtained from the territory itself, and the young are fed at frequent intervals (about every 5—minutes). The cordylines nest solitarily Orin loose colonies, within which each pair defends only a small area around its nest; they forage away from the colonies in flocks, wherever seeds happen to be abundant at
The time. They pack large amounts of seeds into their crop and feed their young at infrequent intervals (about 20-60 minutes). The pair forage and visit the nest together.

The fringelike finches sing only on their territories, and the song serves to advertise the occupation of the territory and to attract mates. The cardueline finches sing anywhere they happen to be, and the song serves as a form of self-advertisement. Manycardueline finches have special song flights over their breeding areas.

Like other birds. All these finches breed when their food is most plentiful. But the timing varies between species. According to what they eat. The chaffinch, which eats caterpillars, has a short breeding season in late spring, while the cardueline finches, which need seeds, have long and varied seasons, in which individual pairs often raise more than one brood. The greenfinch, linnet, and bullfinch, which eat a variety of seeds, breed for almost the whole growing season, continually changing their diet as different plants come into seed. The European goldfinch, which likes the seeds of thistles and related plants, breeds later in summer, while the American goldfinch, which depends even more on thistles, breeds later still. The regular start of its breeding season is the latest in North America.

The crossbills nest in any month, whenever conifer seeds are sufficiently available; in inarch forests, this is mainly in late summer or early fall, in spruce forests in fall to win-tar, and in pine forests in spring. If spruce and pine are available in the same area, breeding can occur continuously for months. Thus crossbills are often forced tones when days are short and cold, and the ground is snow-covered. In the Moscow region, some nests were found in February, when air temperatures were — 9°C (— 2°F); inside the nest, the temperature was as high as 38°C while the female brooded.

Another major event in the annual cycle of finches is migration and here again, food plays an overriding role. The main distinction is between species that feed from low herbaceous plants and those which feed high in trees. Herbaceous plants produce an abundance of seeds every year, but at times of snow, these seeds may be unavailable. Most finches that depend on such seeds migrate south for the winter, and in Europe many thousands winter in the Mediterranean region. Such species have fairly fixed migration routes and show strong homing tendencies, returning to the same areas for breeding and wintering in successive years. Examples include the European goldfinch and linnet.

The tree feeders have a different problem because, although their food is generally available above the snow (enabling them to winter much further north), in any one locality the seed crops vary enormously from one year to the next. In some years the trees and bushes are laden with fruits burin other years they are barren. In different parts of a continent, however, the crops are not necessarily in phase with one another, so in a year when the crops may fail in one region, they may be good in another. With such a fluctuating food supply, there would be little point in individuals migrating to the same places yearly. In consequence.

The migrations are highly variable both in direction and distance traveled. When seed crops are good in the north most of the birds stay there. However, when the northern crops fail, most of the birds move further south. As band (ring) recoveries testify. Individuals of such species may breed or winter in widely separated regions in different years. Enormous year-to-year fluctuations of populations may be seen at any one locality, but the continental population as a whole probably does not fluctuate to such a large extent. This system applies particularly to siskins and redpolls, but also to bullfinches, Pine, and Evening grosbeaks.

The most famous of all eruptive finches are the crossbills. Every few years these birds move out of their breeding areas and occurring enormous numbers outside the normal range. Sometimes, the movements are so spectacular as to attract general attention; as long ago as 1251, the English chronicler, Matthew Paris, wrote about these strange birds which invaded his homeland in great numbers and caused devastation to the apple crop (for the birds are often forced onto unusual foods when away from their favorite conifers).

Eruptions of crossbills have since been recorded from all their main centers, including parts of North America, Japan, and the Himalayas, but have been best documented in Europe. On this con-tenant between ‘So and 1965. Crossbills erupted at least 67 times at intervals of up to 17 years. Only recently have band recoveries confirmed that some birds return to their regular range in later years. From batches of birds banded in Switzerland on migration, some were recorded the following fall and winter in southwest Europe, having continued their journey; others were recorded in later years, 4,0ookm2.5oomi) northeast, in the northern USSR.

Because of their song, bright colors, engaging habits, and simple seed diet, fin-chess have for centuries been kept in cages as pets. Some species breed readily in the cap trinity. And from the wild serine of the Canary Islands all the various strains of domestic canary were deer) vend. Certain finches are also important as pests, notably the bull-finch which eats buds of fruit trees, sometimes devastating orchards.

In the past, man must have had an enormous influence on the distribution and numbers of the different finches. Deforest-non must have greatly reduced the habitat available to certain species. But the spread of cultivated and urban environments provided new habitats for others. One adverse trend in recent decades has been the increasing use of herbicides in agriculture. These chemicals kill the weeds on which several species depend. And in the long term deplete the “seed bank- in the soil.

Plowing and other soil disturbance turn buried seeds to the surface, where they are available to certain finches, but farmland offers much less food for finches than in times past Hawaiian finches (also known as Hawaiian honeycreepers) are thought to be derived from a single finch-like species that crossed more than 3,000km (.r., 860mi) of the ocean to colonize the Hawaiian Archipelago. In the near absence of competition, these immigrants, resembling the Nihau finch, evolved specialized feeding behavior and remarkable bills to exploit highly diverse island ecosystems—from shrubby coral atolls and rocky islets to mountain rain fore-sets receiving more than 1,000cm (400in) of rain per year.

Many seed-eaters retained finch-shaped bills; an extinct, unnamed Oahu species had one of the most massive known. In contrast. The insectivorous creepers have thin warbler-like bills. The Kauai akialoa’sdecurved bill, 6.6cm (2.6in) long (one-third the bird’s length), is used for seeking insects in thick mosses or deep cracks. The Mauiparrotbill chisels into branches for insects with its broad lower mandible. Most remarkable is the akiapolaau, which chips into soft wood with its stout lower mandible while holding its curved upper mandible, with which it later probes for insects, out of the way.
Nectar-sipping species such as the Blackdamp and kiwi have bills that closely match the flower corollas that provide their food and possess tubular tongues to aid in sucking nectar.

Other members of the group eat berries, fruit, snails, and seabird eggs. The colorful red append and dazzling orange kiwi fly many kilometers each day in their search for nectar-bearing flowers, and their evening flights in the thousands can be very spectacular.

The Hawaiian finches have extended breeding seasons beginning in January and continuing through July or August. Because many species are rare and frequently rugged, wet terrain, nests of only half are known. Their nests are open, constructed of twigs and lined with fine fibers, and are well concealed in terminal leaf clusters. Th.eNihoa finch nests in rock cavities, while the Laysan finch, which belongs to the same genus, prefers to nest in grass tussocks omits Sandy Island.

These amazing birds have been decimated by changes in their island homes. At least 15 species, known from undescribed fossils, survived until Polynesians, beginning about 400AD, converted their dry lowland forest habitats to agriculture. Of the 28 species known from records made in more recent times, 8 are extinct and 12 are endangered. Habitat destruction by man and ungulates (primarily cattle, goats, and pigs) and introduced predators and diseases have greatly reduced the numbers of all surviving species. It is hoped that ambitious conservation programs currently underway will protect most of those species that still survive.

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