Canaries are seed-eaters and are known as hardbills, with the typical short, pointed beak of the predominantly seed-eating bird. They have four claws, the first pointing backwards, and the second, third and fourth-forwards. They weigh about 16 grams and normal body temperature is 43.3 deg. C.
Canaries can be mated at one year of age and used for breeding for two to three years. Some have been known to breed for as long as twelve years. They can live for between six and twenty years. It is very difficult to age birds once they are over twelve months of age, except by their appearance: young birds are well groomed, with feet and legs smooth, while the older birds become ragged. Leg rings give some guide to age.
At breeding time the lower portion of the abdomen and vent of the male becomes prominent and protrudes downwards. In the female the vent is swollen but is in line with the contours of the abdomen. At five weeks of age the cock may make feeble attempts to sing and his throat will begin to swell. Cocks generally sing but hens only cheep. Males have a stronger, more thickly set, masculine head. When sexing birds it is easier to compare with other birds in the cage than to make decisions on single birds.
Hybrids between canaries and finches (for example, the goldfinch-canary) are known as mules. Mules are usually infertile, particularly the male.
Nests (round tins, or wooden, metal or earthenware containers) should be hung in the upper half of the cage. Nesting materials that should be placed in the cage include cow hair, meadow hay, grass, pieces of cotton-wool, felt or moss. The incubating period is thirteen to fourteen days.
When hatching commences, give egg food or proprietary nestling food three times a day. Egg food is arrowroot biscuit and hard-boiled egg yolk.
At hatching, the young are blind, and have little down. Eyes open at seven days and the nestling is completely feathered at three to four weeks of age. The young birds moult at six to eight weeks. Adult birds moult annually at the end of the breeding season. A canary under one year old that has not had an adult moult is said to be 'unflighted' and the wing feathers are paler than those of a full adult.