Finch in the context of "Physical dimension"

Size in general is the magnitude or dimensions of a thing. More specifically, geometrical size (or spatial size) can refer to three geometrical measures: length, area, or volume. Length can be generalized to other linear dimensions (width, height, diameter, perimeter). Size can also be measured in terms of mass, especially when assuming a density range.

In mathematical terms, "size is a concept abstracted from the process of measuring by comparing a longer to a shorter". Size is determined by the process of comparing or measuring objects, which results in the determination of the magnitude of a quantity, such as length or mass, relative to a unit of measurement. Such a magnitude is usually expressed as a numerical value of units on a previously established spatial scale, such as meters or inches.

The domestic canary (Serinus canaria forma domestica), often simply known as the canary, is a domesticated form of the wild canary, a small songbird in the finch family originating in the Macaronesian Islands. Over the past 500 years of captivity, a wide variety of coloured, decorative and singing canaries have been bred through selection.

The canary has been kept as a pet for centuries, which began after the European conquests of the islands inhabited by its wild ancestor. They were domesticated and became prized possessions in 17th century Europe, eventually becoming popular even amongst poorer households, largely due to its melodious song and flexibility in breeding. They were also a highly popular pet in the United States from the 19th century until the mid 20th century. Canaries have also been used in the coal mining industry to detect carbon monoxide, a practice that has since been ceased.

The difficulty of defining or measuring intelligence in non-human animals makes the subject difficult to study scientifically in birds. In general, birds have relatively large brains compared to their head size. Furthermore, bird brains have two-to-four times the neuron packing density of mammal brains, for higher overall efficiency. The visual and auditory senses are well developed in most species, though the tactile and olfactory senses are well realized only in a few groups. Birds communicate using visual signals as well as through the use of calls and song. The testing of intelligence in birds is therefore usually based on studying responses to sensory stimuli.

The corvids (ravens, crows, jays, magpies, etc.) and parrots are often considered the most intelligent birds, and are among the most intelligent animals in general. Pigeons, finches, chickens, and birds of prey have also been common subjects of intelligence studies.

The brambling (Fringilla montifringilla) is a small passerine bird in the finch family Fringillidae. It has also been called the cock o' the north and the mountain finch. It is widespread and migratory, often seen in very large flocks.

The Eurasian sparrowhawk (Accipiter nisus), also known as the northern sparrowhawk or simply the sparrowhawk, is a small bird of prey in the family Accipitridae. Adult male Eurasian sparrowhawks have bluish grey upperparts and orange-barred underparts; females and juveniles are brown above with brown barring below. The female is up to 25% larger than the male – one of the greatest size differences between the sexes in any bird species. Though it is a predator which specialises in catching woodland birds, the Eurasian sparrowhawk can be found in any habitat and often hunts garden birds in towns and cities. Males tend to take smaller birds, including tits, finches and sparrows; females catch primarily thrushes and starlings but are capable of killing birds weighing 500 g (18 oz) or more.

The Eurasian sparrowhawk is found throughout the temperate and subtropical parts of the Old World; whilst birds from the northern parts of the range migrate south for winter, their southern counterparts remain resident or make dispersive movements. Eurasian sparrowhawks breed in suitable woodland of any type, with the nest, measuring up to 60 cm (24 in) across, built using twigs in a tree. Four or five pale blue, brown-spotted eggs are laid; the success of the breeding attempt is dependent on the female maintaining a high weight while the male brings her food. The chicks hatch after 33 days and fledge after 24 to 28 days.

Aviculture is the practice of keeping and breeding birds, especially of wild birds in captivity in controlled conditions, normally within the confines of a cage or an aviary.

Some reasons for aviculture are: breeding birds as a hobby, a business like a zoo, or sometimes for research and conservation purposes to preserve and protect some endangered avian species that are at risk due to habitat destruction, the illegal wildlife trade, diseases, and natural disasters. Aviculture encourages conservation, provides education about avian species, provides companion birds for the public, and includes research on avian behaviour. Popular birds people like to keep and breed include budgerigars, cockatiels, finches, macaws, domestic canaries, columbidae (pigeons and doves), loriini (lories and lorikeets), cockatoos, conures, and African grey parrots.