Around half of garden owners regularly feed wild birds, and as a nation we spend over £200M each year on seed and peanuts. We provide nest-boxes for a select group of species, and this has morphed into an increasingly hi-tech form of wildlife watching, with cameras allowing us to watch our birds on our TV screens. We know that we can make a real difference to the abundance and survival of garden birds. The recent and rapid expansion of goldfinches has been a welcome result of the provision of nyger seed in specialised feeders. Blackcaps are increasingly frequent winter visitors to gardens, with research suggesting that our summer blackcaps travel south in winter, and they in turn are replaced by migrating central European birds, attracted by the predictable and abundant food provided in gardens. Nuthatches are now common visitors to gardens, where once they were scarce, and they have been joined by huge increases in woodpigeons, magpies and exotic additions to our avifauna such as the ring-necked parakeet.
But of course it is not all good news. Some of our most common garden visitors have declined at a startling rate. Within a couple of decades we’ve lost huge numbers of house sparrows, starlings and song thrushes from across the country. We do have some understanding of why this is happening, but as a nation of bird-supporting gardeners are we doing enough and are we doing the right things to help support wild bird populations? This is where SongBird Survival has stepped in, funding a new research project which we hope will begin to answer these critically important questions. I have just started my PhD research at the University of Reading, where I will work to provide insights into what we can do to help our garden birds.
Garden birds face a huge number of challenges, many of which are unique to their urban ecosystem. The most important difference is that birds in urban areas receive a relatively large volume, but limited range, of supplementary food. This favours some species, such as finches and tits, over others, such as warblers and thrushes. But supplementary feeding is surprisingly complex in its potential effect on the assemblage of species found in gardens. For example, our previous work has shown that the numbers of insects found in gardens is lower near feeders which may in turn affect nestling survival. Building on this, we speculate that feeders also provide resources for potential predators of eggs and nestlings, such as corvids, grey squirrels and great spotted woodpeckers. Just how much food these species take is not well understood. Are we inadvertently providing resources for the species who may act as significant predators of urban songbirds? If birds nest near feeders are they more likely to be predated? Just how effective are feeders which exclude such species, and does their use affect local nest predation? Each of these are important questions for urban birds and my first job will be to test this using remote cameras and artificial nests, studying how the structure and location of feeders affects nest predation rate.
But garden bird success goes far beyond this. Not only do birds need to avoid nest predation, raising chicks demands suitable food and there is thought to be a shortage of insects and other invertebrates in suburban and urban areas compared to more natural habitats. That shortage may help our garden plants, but nestlings need a diet high in protein and suitable vitamins that invertebrates provide and typical supplementary foods lack. This particularly hurts birds that only have single broods such as blue tits and great tits, which may as a result produce fewer fledglings. Will the planting of insect-friendly vegetation or the provision of more protein-rich food such as mealworms overcome this? By using specialised equipment I will be able to study how often parent birds use feeders, and to consider the success rates of their broods.
But supplementary feeding may also play a more hidden role in the survival of our garden birds. The role of disease is poorly understood, but the gathering of birds at bird feeders could potentially increase the risk of disease spread. The spread of Trichomonosis in Greenfinches suggests just that, but there is a lack of scientific evidence to see how serious this is. This provides a final thread to my initial research.
With SongBird Survival’s support I hope to cast new light on these issues and others to seriously improve how we look after our gardens for the betterment of wild birds in all our lives.