Monday, 28 November 2011

Part 4: Rise of the red factor

Red Siskin
Canaries are yellow. This is one of those ‘everybody knows’ facts that are in reality completely untrue. As you will have seen from images on previous posts, canaries come in all shapes and sizes, and are often greenish-brown rather than yellow. Up until the start of the 20th century however no one had succeeded in breeding a canary colour that was not a variation on the colours in the wild bird.

It was at this point that someone wondered if a new colour could be introduced from a different species altogether. It was already known that canaries would hybridize with other species of finch – in fact show schedules even today have a special section fro these hybrids, which are referred to as ‘mules’. Except for hybrids with the European Serin, which is involved with the origin of several continental breeds, practically all of these were believed to be sterile. This was in the early days of genetics, but the reason is probably differences in chromosome numbers.

Nonetheless, experiments were made with finches carrying various colours, especially red, and eventually it was discovered that male hybrids of the canary and the South American Red Siskin Cardualis cucullata retained some fertility. Further crosses back to canaries eventually resulted in a fully fertile canary whi9ch was capable of expressing red in its plumage.

Red Factor
The red in the feathers of a red factor canary is a lipochrome pigment related to the yellow in the normal bird. As with the yellow, the pigment is ultimately derived from the diet. For this reason birds entering the moult in particular must be fed a diet containing the chemical precursors, or the bird will develop feathers with insufficient depth of colour. This is supplied today by a commercial additive, but in the past it was supplied as far as possible by feeding a diet containing natural precursors.

It was soon discovered that not only the red factor had been incorporated into the red factor genome. Unlike wild canaries, Red Siskins are sexually dimorphic, and this dimorphism became established in one of the newly developed breeds. Called Dimorphics or Mosaics, these show colour points on the wings that differ in males and females.

With the new palette of colours available, an interest developed in a section of the hobby for breeding canaries for colour rather than type. Mutations in the concentration and distribution of eumelanin and phaomelanin have resulted in a variety of distinctly different colours.

Brown Isobel
Unfortunately, the original demand for Red Siskins to create these new colour canaries resulted in a ‘gold rush’ of trappers taking them from the wild. Although the species is now protected, a combination of illegal trapping and habitat destruction has put the species on the Endangered list. Although the pure species has been bred, the captive population is extremely low.

Next week: How the canary was sent down the coal mine.

(images from wikipedia,

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