The Almond Tumbler is a colour variety of the English Short Faced Tumbler and a very special breed to pigeon fanciers, not only does it have an attractive colour combination it also has a very dainty appearance, added to this the breed is well documented in various books that would have been read by Darwin. These books show the development of the head and beak size, the beak sometimes being compared to that of a Goldfinch (Cardeulis, cardeulis), the small size being achieved in a little over a hundred years. Darwin would discover in his anatomical studies just how short the beak had become in comparison to the wild type Rock Dove.
The colouring of the Almond Tumbler is fairly well understood by fanciers today but I do know of those who still find the genetics of the colour a mystery.
The classical Almond colour of the bird is a mixture of sex-linked, auto-somal colours and dominant patterns and modifiers, when pairing two Almonds together an array of colours such as red, yellow, red and yellow agates, deroys and kites are just some of the colour possibilities. Another factor which makes breeding the Almond Tumbler more difficult is the problem of a sex-linked lethal gene which affects the cock birds if they are double factor almond, usually dying in the nest or should they survive will often have degrees of blindness or a clumsy character. However, the dominant nature of the almond gene has helped the spread of the colour into many other breeds. An Almond Tumbler hen paired to any cock bird will produce single almond factor cocks but these cocks may not show the true classic almond expression. Almond Tumbler cock birds become darker flecked than the hens after each moult and at five years of age are usually too dark to put on the show bench.
Darwin would have needed more than a couple of years pigeon breeding to fully comprehend the difficulties of breeding this colour.
Other colours in English Short Faced Tumblers include Beards, Baldheads, Rosewings and Mottles and these, although not as complicated to breed as the Almonds, still need a far amount of skill and application.
The almond colouring probably originated from the Oriental Roller pigeon.