Churchyard Nature Note with Andrew TompsettJuly 2015
The moult is a time when the old worn, faded and soiled plumage is cast off and new feathers break through. With the loss of wing feathers, flight is much reduced and for safety’s sake most birds lie low at this time since it is positively risky to advertise their presence when vulnerable to attack by predators. Feathers are cast off and new ones emerge over a period the new ones appearing rapidly in a few weeks. With migratory species it is better to complete the moult before departing, however, there are some exceptions with some long-distance migrating species where moulting occurs later in the winter destination. This makes perfect sense since to lose one’s feathers during the journey would obviously be very risky. Young birds do not moult as they already have a fine set of feathers which serve them well when migrating or for the coming winter as semi-residents here. There are, in fact, many variations in the timing of this annual renewal of the plumage largely depending upon the duration of the breeding season and the kind of migration being undertaken
All of this behaviour, which may seem perfectly logical to us has been carefully worked out to suit the habits of each species. What is more, this behaviour is passed on from generation to generation.
The bird world is full of amazing details. How is it that many parent birds migrate before the young ones, yet the youngsters can still make the journey unaccompanied?