I made a comment a few days ago “wow there’s a lot of angry birds in my garden”. I watch them a lot to see if I can identify patterns in their behaviour, to find out which species/individuals always get the food, and which species/individuals get the water to drink or bathe in. Over the last week or so I’ve had a Robin (Erithacus rubecula) with an almost bald head visiting, I’m not certain but it might also have something wrong with its right eye, so I always look out for that particular bird to see that it manages some food before it’s bullied away by another bird. Having looked it up, it seems the poor Robin might have mites, and there’s not much to be done except making sure it gets food. As I write I think it’s just appeared at the suet pellets – but I don’t want to move too much to check and then scare it away, and I can hear and see aggressive Goldfinches (Carduelis carduelis) fighting each other for the nyger seed. The Starlings (Sturnus vulgaris) seem to be the most aggressive though.
Luckily, Twitter served up a paper last night entitled “Dominance hierarchies and foraging strategies in supplementally fed garden birds”. It explains that aggression and competition for resources use a lot of energy, and fighting causes injury and sometimes death. So often, when the competition is ‘won’ repeatedly by particular individuals, a hierarchy will be formed with certain birds being dominant or subordinate, and they come to assess their chances of winning a fight prior to engaging.
The paper also states that three quarters of UK households regularly feed the birds. By feeding them, we are likely to have enhanced the survival and reproductive success of birds, but we are also likely to have increased the competition for food, both within and between species. Research reported in the paper found that socially dominant, heavier species of birds with higher body mass, monopolise access to higher value foods. Whereas lighter species were constrained to food with lower value. This has implications for conservation when supplemental feeding is being used as a tool.
Advice from the RSPB states: to reduce competition, offer a variety of food, and if possible space it out in your garden. Think of the smaller bird species and offer food in hanging feeders with cages which the larger species can’t get in. If you have a wooden post, you can fill cracks with suet, to attract small agile birds such as Blue tits (Cyanistes caeruleus) and Great tits (Parus major). Dunnocks (Prunella modularis) hop around under hedges and like to feed on the ground, so food can be put on a tray on the ground for them, or small amounts suet pellets can be scattered directly onto the ground.