The Chaffinch is one of our more familiar birds with a significant population – some six million territories – and a broad range of habitats within which it breeds. It is a regular garden visitor, attracted to seed provided in hanging feeders and on bird tables.
The Chaffinch’s scientific name Fringilla coelebs was assigned by Linnaeus in 1758 and refers to the bird’s migratory behaviour; ‘coelebs’ means ‘unmarried’ and Linnaeus gave the Chaffinch this name when he observed that the birds wintering around his home in Sweden were mainly males. The females from northern breeding grounds wintered further south than the males, a pattern of behaviour known as differential migration – where one sex or age group shows different migratory behaviour to another. Generally, females and juveniles winter further south than adult males, suggesting that competition for food and roosts may decide which birds can winter at higher latitudes.
It is not unusual to see Chaffinches with grey or off-white rather ‘crusty’ leg growths. There are two main causes: mites of the genus Cnemidocoptes, and a virus called Chaffinch Papillomavirus. They are fairly similar in appearance and there is evidence to suggest that both can occur together. Although most birds showing signs of these diseases are bright, active and able to feed, some become lame and others may suffer from secondary bacterial infections. While captive birds with mites can be treated it is not possible to target wild birds with suitable medicines, leaving good hygiene practice at garden feeding stations as the best way to reduce the impact of these diseases.
The recent decline in Chaffinch populations shows a change in fortune for a species which had been increasing in numbers over recent decades. We know that Chaffinches were affected by the 2006 outbreak of finch trichomonosis, with a decline in numbers of a fifth recorded in some regions; but things seemed to go back to normal after a couple of years. Then, for some reason there was another noticeable decline in the reported numbers in 2013/14.
We all know that the plumage of the male Chaffinch changes through the course of the year, being at its finest ahead of the breeding season. But did you know that the steely-blue colouring of the head and nape, which contributes to the breeding plumage, is not produced by the bird moulting through new feathers. Instead it is the dull brown feather tips that wear away to reveal the colour hidden away below.
British birds are slightly smaller but more brightly coloured than the continental immigrants who arrive to join our resident birds in late autumn. These arrivals often bring smaller numbers of the related Brambling with them, a real treat for garden birdwatchers. The numbers of both species wintering here may be influenced by the size of the beech mast (seed) crop across Europe. In those years when the crop is poor we see more of them, with many moving into gardens to take sunflower hearts and high energy seed mixes, especially when our beech mast crop is poor too.
If you find the lives of our garden birds to be of interest, and would like to join in and count the feathered occupants of your garden, please contact me or visit the BTO Garden BirdWatch website (www.bto.org/gbw). If you know of a local organisation who would like a talk on garden birds call: Mike Gray 07596 366342 or firstname.lastname@example.org.