We have been enjoying an extensive flock of American Robins in and aorund the garden for a couple of weeks now – one assumes that they are the same birds each day but, of course, they could be a constantly changing flock as one day’s birds move south for wintter onyl to be replaced by newcomers from further north. One Robin looks pretty much like another, after all. Perhaps the “new birds every day” explanation is what is happening as amongst the regulars bathing at the pond this morning appeared this striking different leucystic bird.
To quote from a Cornell Lab of Ornithology explanation – “Leucism is a genetic mutation that prevents melanin from being deposited normally on feathers … leucism comes in two main varieties — paleness, an equal reduction of melanin in all feathers; and pied, an absence of melanin in some feathers creating white patches … Typically birds with abnormally white feathers do not survive long because they are so much more visible to predators. Those that do survive may have trouble attracting a mate. Consequently, the mutated genes that cause albinism and leucism are less likely to be passed on to a new generation.”