Thanks to a Durham resident a wildlife oddity has come to the Trust’s attention. Duncan Blakemore arrived at the Trust’s office claiming to have seen a white blackbird. That is not the most unusual wildlife report that the Trust has received, we’ve had numerous big cats, arctic foxes and so on, but this report was different – it came with photographic evidence.
If you want to be taken seriously, get a photograph. The photograph in question can’t be disputed; it’s a white (almost) blackbird. As Duncan pointed out he first assumed the blackbird was some sort of albino, but in fact the bird is leucistic.
Albinism is a genetic condition where the body fails to produce the pigment melanin and the absence of melanin gives the characteristic pink eyes seen in albino animals. The pinkness is the result of underlying blood vessels showing through due to the lack of melanin pigment. Leucism is also a genetic condition, but one where all pigments, not just melanin, are produced at lower levels. Leucism affects only certain tissues in the body; hence the blackbird in question has normally pigmented eyes. It is also common for leucism to only be partial, which is why the Durham blackbird has both black and white feathers. In other species, such as horses and dogs, this partial leucism is quite common and produces animals that are known as pied or piebald.
But please spare a thought for our partially leucistic friend. There is good reason why blackbirds are black. Predators can spot leucism a mile off.