Bird Watching (UK) - - Species Finches -

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.

Colour­ful plumage

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...


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