This week I thought I would let you know about something you could do to help the British Trust for Ornithology (BTO) without having to leave the comfort of your own home (after all, no-one wants to be out in the rain!) The BTO have lots of volunteer surveys that people can take part in and one that is running at the moment is the Abnormal Plumage Survey. It is a study looking at abnormal plumage of British and Irish garden birds. They would like our observations of birds in gardens with unusual plumage characteristics, notably those associated with pigmentation problems. Plumage abnormalities associated with feather loss are not being recorded through this survey. You can find the survey by following this link – http://www.surveymonkey.com/s/plumagesurvey. If you don’t want to do the survey but have any photographs of birds with abnormal plumage you can email them to: email@example.com.
Having plumage that differs from the population ‘norm’ is often disadvantageous, giving the wrong signals to other individuals or making the bird more obvious to would-be predators. Feathers with reduced pigment are often less robust and wear more rapidly, reducing flight efficiency and decreasing their insulative properties.
There are several different forms of plumage abnormality centred on altered amounts of pigment. These include leucism and albinism (where there is loss of the pigment melanin), melanism (in which the amount and/or distribution of dark-coloured melanin pigment is often elevated), erythrism (where a chestnut-red pigment replaces certain other pigments) and flavism (where there is an excess of yellow pigment). Both erythrism and flavism are thought to be rare compared with leucism and melanism.
Blackbirds (see picture) seem to be the most commonly affected/recorded along with house sparrow, jackdaw, carrion crow and chaffinch.
Laura Preston – Scottish Wildlife Trust, Falls of Clyde Ranger