Garden bird feeding is an institution in Britain, with almost half of households engaging in the practice. It’s a relatively easy method for people to engage with local wildlife, which according to growing evidence may provide physical and psychological health benefits. Its impact on birds, however, isn’t as benign as it may appear.
Some species benefit from supplementary feeding, usually via increased overwinter survival. Blackcaps – until recently fleeting summer visitors to Britain – have done especially well out of it. Since the 1960s, blackcaps from German breeding populations have increasingly been wintering in Britain rather than making their typical migration to Spain, saving time and energy. On returning to Germany in spring, the birds that winter in Britain arrive and breed earlier than their Spanish-bound counterparts, driving evolutionary divergence: the British wintering birds have shorter wings (an adaptation to shorter migrations).
The weak lose out
More generally, though, there are reasons to be sceptical of bird feeders. First, not all birds use them equally. A few bold and adaptable species are better able to take advantage of feeders; among these are blue tits, great tits, starlings, wood pigeons and house sparrows. Some exert dominance in interactions at feeders, boosting the numbers and physical condition of these species. Therefore feeding could have detrimental effects on less adaptable competitors and the wider environment.
Another notable problem is disease transmission.
Bird feeding stations create artificially high aggregations of multiple species that wouldn’t ordinarily come into close contact. Post-Covid we can all recognise that this is a good strategy for passing around pathogens. Several avian diseases are linked to garden feeders, the most well-known in the UK being trichomonosis in greenfinches, recently also affecting chaffinches. This protozoan parasite is thought to have passed from pigeons – which are usually unaffected by the disease – to other birds via shared garden feeding stations. In greenfinches and chaffinches, at least, it is driving population collapses.
‘Sadistic death traps’
And feeders don’t just feed birds. Concentrated bird activity around feeders may attract the attention of local cats, turning the feeders into sadistic deathtraps. Wild predators are also actively attracted to them, in particular nest predators such as magpies, jays and grey squirrels, which in spring significantly increase predation of nests in the immediate vicinity.
One should also remember that the bird food sold in your local garden centre must be grown somewhere. Farms producing it must by definition discourage birds as pests if they want a harvestable product
The Royal Society for the Protection of Birds (RSPB) does go out of its way to provide sustainable, nutritious bird food. However, it doesn’t seem keen to emphasise issues around the perils of feeders, perhaps because a substantial proportion of its revenue comes from commercial operations, such as the sale of feed and feeders. As a whole, the bird feeding industry in the UK was estimated in 2006 to be worth £200m annually, and it is likely to have grown substantially since then.
Unless, as the RSPB suggests, you clean your bird feeders with disinfectant every few days, you may be doing more harm than good. You also need to relocate the feeders regularly to prevent faecal accumulation and, if possible, find means to keep cats away.
Create a bird haven
The easiest way to make your garden a haven for birds and other wildlife would be to stop using chemical pesticides: insecticides, molluscicides or herbicides. These either wipe out the creatures that birds feed on or indirectly poison the birds themselves.
You can also improve the habitat for birds, integrating a variety of trees and shrubs into your garden. This offers our avian friends shelter, nesting sites and food sources such as shoots and berries.
Planting native species in particular gives better habitats for the invertebrates on which most garden birds depend.
It also helps to cut down on the times you mow your lawn. Also don’t be too obsessive about tidying borders at the end of the flowering season: by being left alone – however untidy they may look – grasses and herbaceous plants have a chance to provide seeds, entirely for free.
The destructive trends towards gardens being paved, mown to within an inch of their lives, covered in hideous plastic grass or drenched in toxic chemicals, won’t be offset by hanging out a tube full of peanuts.