Recently I was out taking photos when I came across a strange looking bird – from a distance I couldn’t tell what the bird was. Walking closer to the bird, snapping photos as I gained ground on it, I realized it was a robin that had partial leucism.
Out of curiosity I asked TJ Walker, NGPC District Manager, Wildlife Division and avid birder how common this was, his response was “I have seen leucistic birds in many species – mallards, gadwall, ring-necked pheasant, Sandhill crane, eared grebe, American robin, Northern cardinal, dark-eyed junco, red-winged blackbird, common grackle, house sparrow and several others that I was not able to identify what species they were.”
Walker also said “Leucism seems to be more prevalent in robins and blackbirds, but that may be because we have so many of those species in our area. Leucism may occur on one in 10,000 or 100,000 birds. At certain times of the year it would probably be easier to find a bird with leucism in bird species that are here in crazy numbers like during migration periods.”
Leucism is a condition in animals characterized by reduced pigmentation that is caused by a reduction of skin pigment, particularly melanin. This lack of color causes several color changes in birds like white feather patches where the bird normally doesn’t have white; birds may possess a paler overall plumage that looks faint or a bird may have an overall white plumage with little or no normal color that resembles albinism.
The degree of leucism, including the brightness of the white and pigment loss will vary depending on the bird’s genetic makeup. Birds that show only white patches or sections of leucistic feathers are sometimes called pied or piebald leucistic birds, while birds with fully white plumage are referred to as leucistic birds.
Leucism affects only the bird’s feathers, and typically only those with melanin pigment or what would typically be dark feathers on the bird. A leucistic bird with different colors may show some colors brightly, especially red, orange or yellow, while feathers that should be brown or black are instead pale or white. Some leucistic birds can lose all the pigment in their feathers and may appear pure white. This does not mean that the bird is an albino.
Albinism affects all the pigments not just in spots like the robin I photographed. Albino birds show no color whatsoever in their feathers and have pale pink or reddish eyes, legs, feet and a pale bill – leucistic birds often have normally colored eyes, legs, feet and bills.
It is possible to identify leucistic piebald birds – they will possess other normal plumage colors and only have patches of white feathers, but their plumage can be used for identification aside from their white feathers as is the case with the robin.
Many birds with leucism show a faint wash of color in recognizable patterns on their feathers, but the color may not be as strong as a normal bird. Sometimes the color patterns leave birders scratching their heads – not knowing for sure what species of bird that was.
Pure white leucistic birds can be more challenging to identify – look for size and shape of the bird, its range, feeding habits, behavior and what other birds it flocks with to help identify the species.