Mutant blackbirds in my garden

Picture by Tom Rayner

About three years ago, we had a blackbird in our garden with a white wing. I’d never seen anything like that before, although when I was a cub reporter, I once did a story about a pink starling spotted in Northwich (they’re fairly common apparently).

Anyway, we watched white wing for a some time before he disappeared from view and memory. I thought he might have grown some new black feathers or popped his clogs.

He may well have done, but before departing this life he seems to have spread his mutant genes around a bit. There are now at least four blackbirds (black males and brown females) with white patches. One has a white wing patch like his dad; another has a white blob on her head.

These birds are currently busy playing the mating game, chasing each other around the garden and chasing away potential rivals. So what will the next generation have in store? Will my blackbird population (which has risen in recent years) get back on message, or can I expect more mutations? I might have Dalmation-coloured black-and-white-birds everywhere!

I have been checking online and it’s not only my birds that are displaying this phenomenon. The British Trust for Ornithology runs an annual plumage survey which checks for just this kind of thing. This is what they said about the latest survey findings:

Across the country, householders have been seeing Blackbirds with strange white markings. The condition, typically referred to as ‘leucism’, is one of a number of plumage abnormalities to have been reported through the BTO Abnormal Plumage Survey.

In less than a month, the survey has clocked up nearly 700 sightings, encompassing more than 35 different species. Three quarters of records have been of leucistic birds and, of these, nearly half have been Blackbirds. Leucistic birds may be confused with albino individuals, but the latter have pink, instead of dark eyes, and only account for 12 per cent of survey records to date.

It is not yet clear why Blackbirds appear to be particularly affected. It could be that they are unusually susceptible to the condition. However, being black or, in the case of female Blackbirds dark brown, any light-coloured feathers show up particularly clearly. Indeed, several other species with all-black, or mostly black, plumage have been spotted with white feathers fairly often, including Carrion Crow (49 records) and Jackdaw (40).

Picture by Tom Rayner