MY FIRST EXPERIENCE of bird ringing was at university, when I worked on a winter research project studying Chaffinches. We were investigating the effects of feather mites on wild birds, and my job was to inspect the wing feathers of each bird for the tiny mites. However, the birds themselves, so briefly held and then released, were of far more interest to me than the parasites. Even in winter, the black, blue and brick-red heads of the males, their green lower backs and intricately patterned wings were stunning. For me, as perhaps for others, the amazing details of these common garden birds had previously passed me by, but those ringing sessions were an education in taking a closer look, and were my first steps to a career in ornithology. As well as receiving a lesson in the plumage and anatomy and wonder of birds, I did also learn about feather mites. Our measurements didn’t find any link between numbers of mites and body condition, and it appears that these parasites, which live between the fine filaments of the feathers and feed on the oil produced by the preen gland, are relatively harmless passengers. However, Chaffinches do suffer from other, more serious, parasites and diseases. One of the most visible conditions is swollen, scaly legs and feet, known as leg mange or scaly leg. There are actually two main causes of scaly leg: an infestation of Cnemidocoptes mites, or a viral infection known as papillomavirus, which both have similar effects. Birds with these conditions generally appear otherwise to be in good health, though as the condition worsens they may become lame, less able to forage and vulnerable to predators. The BTO collects information on diseased garden wildlife through the partnership project Garden Wildlife Health, and are monitoring the presence of scaly leg in Chaffinches across the UK. Chaffinches are also affected by trichomonosis, the parasitic infection that emerged suddenly a decade ago and has led to a crash in Greenfinch populations. While reports made to Garden Wildlife Health show that Chaffinches often suffer from this disease, they appeared to have avoided the severe mortality suffered by OBSERVED Chaffinch breeding numbers and reports of diseased birds are being closely monitored Greenfinches, and overall populations had been holding up. However, Breeding Bird Survey results from 2013 and 2014 showed that numbers of breeding Chaffinches dropped sharply in those years and, as I write, we are awaiting the final figures for the 2015 breeding season. Could this be an effect of disease, or could there be another cause? Perhaps this is merely a dip, and numbers will be back up again before long, but we will be monitoring both Chaffinch breeding numbers, and reports of diseased birds. Despite the recent downturn, Chaffinch numbers are still much higher than they were at the start of routine monitoring in the 1960s, having shown fairly consistent increases from the 1970s to the 2000s. We have an estimated 6.2 million breeding pairs in this country, making this our third most numerous breeding bird behind Robin and Wren, and numbers swell further in winter by arrivals from northern Europe and Scandinavia. Though originally a woodland species, Chaffinches have adapted well to suburban and garden habitats, as well as to fragmented woodlands and hedgerows, and it appears that, at least until recently, the changes in our countryside have been to their benefit.
FW1F 2 3 4M 5 6W 7 8F 9 10 11M 12 13W 14 15F 16 17 18M 19 20W 21 22 23 24 25M 26 27 28 29F 30Sa 31 6.54 6.68 6.89 7.08 7.23 7.32 7.31 7.19 6.95 6.66 6.38 6.14 5.93 5.83 5.87 6.07 6.35 6.52 6.75 6.92 7.06 7.17 7.21 7.13 6.94 6.71 6.48 6.30 6.24 6.28 6.44 6.67 6.84 6.96 7.04 7.07 7.03 6.88 6.67 6.45 6.24 6.01 5.83 5.80 5.95 6.23 6.61 6.78 6.90 14:54 6.98 7.03 7.01 6.93 6.80 6.65 6.50 6.37 6.37 6.49 6.70
Even in winter, the black, blue and brick-red heads of the males, their green lower backs and intricately patterned wings, were stunning