I remember Greenfinches vividly from childhood; I was a member of the Young Ornithologists Club and my parents would put a bag of peanuts up in the garden to attract birds and give me something to look at from the house. The Greenfinches would turn up en masse and compete vigorously for food, flashing their yellow wing bars and bickering. I became very used to seeing them and I guess I began to think them commonplace, a great injustice given the astonishing range of colours they are possessed of. Now they seem exotic and vulnerable, all the more so given the precipitous decline in population caused by the Trichomonosis parasite.
This calamity was documented in 2012 by Cunningham et al. (Phil. Trans. R. Soc. B, 2012, 367, 2852–2863). The infection was first identified in 2005, with epidemic mortality identified in 2006 and in subsequent years. The disease is most unpleasant and I won’t go into detail; Cunningham’s open access paper provides an introduction to the nature of the disease and the grim business of counting the dead. Greenfinches now have Red UK conservation status.
Much of the data used to track the infection and the changing Greenfinch population was provided by the long term BTO Garden Bird Feeding Survey, a rigorous activity involving regular monitoring at ca 275 sites across the UK between October and March. The Survey continues to yield useful information; for example, the changes in composition of British bird communities associated with long-term garden bird feeding have been assessed using data from the Survey (Plummer et al., Nature Comm., 2019, 10, 1-8). The progress of the epidemic was also tracked via the recovery of rings from dead birds. The BTO has a long established ringing programme which we’ve interacted with close to home in Kelvingrove Park. I’ve some images of a Greenfinch which was caught, measured and ringed during a session in December 2022.
I wasn’t aware of the extent of the data collected on these occasions; birds are weighed (this involves them spending a short time head down in a plastic tub) and measured, and their general condition is assessed. I was really interested to learn that periods of poor feeding can be identified from tiny grooves across the feathers. These datasets enable the BTO to profile bird health across the population. I enjoyed the opportunity to see one of these brilliant birds at close range. I particularly liked the opportunity to see the wings, which were extended and spread as part of the examination, rather than for my benefit.
White balance is always tricky but I hope I’ve rendered the colours accurately; these finches have several yellows, greens and greys. The ringing took place on a dark December day but when the sun hits these finches, they are dazzling.
Though this image is a little grainy (the bird was about 15m away and through a window), I like it because of the iridescence of the breast feathers.
We heard this chap before we saw him; we were walking along the Clyde towards Cambuslang and he was commanding his territory with some vigour.
We see them regularly at the seaside, perching and feeding on the wild roses behind the dunes. They often flock with Linnets and we’ve seen them feeding on the sand above the high water line.
Although they were on a busy beach and their visits to the ground were short, all the birds in the image seem to have a beak full of something, but what? I was surprised to see a huge amount of Beech mast in the sea very close to where the birds were feeding. I wondered if the water had freed the nuts from their cases and cast them higher up the beach. I can’t find a good source to tell me if 2022 was a mast year (when acorns, nuts, winged and other seeds cascade from the trees). It could be that they’ve found a crop of mature seeds from a sea vegetable – that’s probably a simpler explanation.
This weekend sees the Big Garden Birdwatch and I imagine our regular Greenfinch will turn up and compete for sunflower hearts. Being a bit of a unit, he isn’t easy to shift from the feeder but weight of numbers of other species cramp his style. Plummer et al. (PLoS ONE 2018, 13(9), 1-13, e0202152) found “a significant positive association between body mass and dominance across ten passerine species of birds that were observed to compete regularly at supplementary feeding sites.” I’ll come back to this hierarchy one day in a post about another finch species. I haven’t seen our Greenfinch today so I hope he’s well and getting in good nick for a successful breeding season.
backwoodsman.org 