the phrase to tail off into disaster, like a human youngster endlessly practising a tricky piece on the piano. However, by the time that you are listening now, at the height of spring, the Chaffinch will have perfected its song so it no longer sounds amateurish. The adults don’t amend their songs, but they too will need to prepare. After the breeding season, hormonal changes dampen pretty much any breeding activity, including all song, and the birds enter into what is known as the refractory period. This continues into mid-winter, so the autumn is quiet, with nobody holding territory or making anything other than contact or flight calls. It is only when the days begin to lengthen that this changes. Over time, testosterone is released in greater quantities into the bloodstream and makes the testes grow. It also stimulates the birds to begin singing. At the same time, previously sociable birds leave flocks and, for an increasing part of the day as the spring progresses, they pay attention to their territories. Soon they are on post all day, from dawn to dusk. All the while, they also make the switch from seed-eating to a primarily insectivorous diet. It is change all the way. For some individuals, the preparation also requires a shift to the breeding site. In the case of most British breeding birds, this might only require a move of less than a kilometre, but for younger birds it can be more.
The preparation to sing, therefore, is long and complicated; a biochemical and neurological marvel. So what of the plumage, that switch from relatively drab to pleasingly colourful? Is this too a similar pathway of chemical messages and physiological uproar? Surprisingly, it isn’t, although you could argue that the preparation for the spring wardrobe begins early on, during the autumn in fact. But what happens is actually a delicious short-cut. During the autumn moult, the bird grows both its winter and breeding plumage at the same time. You’ve probably seen those showbiz acts where the actor slips off an over-costume to reveal one beneath, that completely alters their appearance. This is similar to what the Chaffinch does, except that the process is more subtle. When a Chaffinch grows its winter plumage, the tips of the feathers are relatively drab brown, giving the head and body a relatively cryptic appearance. However, a millimetre or two in from the tip of the feathers, the colour is quite different, being pink inside on the breast feathers and blue on the crown. As the unremarkable and inevitable process of wear and tear acts on the tips, over the winter months they wear away to reveal the more colourful sub-terminal pigments. Ironically, the fresh, newly-grown feathers of autumn give a dull, faded look, while the heavily worn feathers of spring, make the bird appear neat and colourful. So, there is one thing in the performance of the Chaffinch that really is a little cheap and cheerful. The song might be a thing of fresh beauty, but that old costume really does belong at the end- of-the-pier cabaret. The striking spring appearance comes not from fresh plumage, but rather from worn feather tips Three Chaffinch dandies strike New Romantic poses...
YOU WEAR IT WELL