I'm asking this question as last winter we had one female house sparrow with several white feathers forming a bar on her left wing, the rest of her colouration was normal though we had a hard timnme identify her, we though female cff, no beaks wrong, and settled on very partial leucinism. Then come the breeding season she's gone. Assumed she's died, and now at the same time of year as we spotted her she's back, in amongst the sparrows.