Saturday, 18 August 2012

Patterned plumage

The local blackbirds have successfully fledged another brood. The tropical-sounding chirps of the youngsters have been evident for several days now, even if the birds themselves have not. The parent blackbirds divide their efforts between the offspring, each chick most likely tucked up in cover somewhere around the garden, having just left the nest. The calls attract my attention and one hopes that the local cats are elsewhere at this critical stage.

It was only this morning that I saw the chicks for the first time, now developed enough to venture from cover to seek food around the bird table and from the large border in which it stands. It is clear that these youngsters have a lot to learn. Instinctively, they seem to peck at everything, swallowing some items that I cannot imagine would prove edible. So long as they don’t prove to be toxic no harm should be done. The adults look fatigued, their plumage tatty and suggestive of a long and difficult season. I suspect that this will be the last brood of the year for these birds and I wonder how many chicks they have managed to get off since the first nesting attempt, made many months ago.

Other blackbird youngsters have already started to moult through some of their body feathers, the warm gingery browns of youth being replaced by the more sombre feathers of adulthood. These young birds look most peculiar, like a parlour game in which two different species have been spliced together to form some new creature. It is easy to see why they cause confusion among those just starting out with birdwatching; such intermediate plumages are often absent from field guides. The same thing happens with young starlings which, part way through their moult, are neither one thing nor the other.

Most young birds will have left the nest with their body plumage not fully developed. All the effort has been directed towards attaining a size at which the chick can leave the nest and fly. In the warmth of summer the full complement of body feathers can wait a few weeks. Once the chick has become safely independent then it can add the extra feathers in preparation for what lies ahead. For these young blackbirds the future is likely to be a winter spent here in Britain, perhaps with some local movement out of town to feed on autumn’s bounty and a period of dispersal to where, next year, they will set up territories of their own. For other birds, like the nestling swifts, the future holds a staggering journey south, to wintering grounds that stretch beyond the equator. The next few weeks will be critical, as preparations are fine tuned and journeys begun.

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