Should I feed birds? Pros and cons

In the UK it is estimated that as many as 3 out of every 4 households feed wild birds, and more than £200 million is spent annually on bird feeding. In the US more than 50 million people feed birds and, according to the book Feeding Wild Birds in America (by Paul J Baicich, Margaret A Barker and Carol L Henderson) the US market was a staggering $4 billion on bird food alone in 2012. It is clear that feeding birds is a very popular pastime, but is it good for the birds?

Feeding wild birds can certainly be considered unnatural. However, humans have altered the natural environment so much, generally negatively and leading to declines in most bird populations, that gardens can conceivably compensate in some way. There is no doubt that feeding can influence most aspects of birds’ lives, including nesting, behaviour, distribution and longevity. The key question is whether feeding wild birds is damaging to the birds or other wildlife.

Why feed birds?

The main argument for feeding birds being beneficial is that it supplements their natural food supply, particularly in winter when this may be in short supply. At this time of year several species migrate to warmer climes in search of easier food, whilst those that remain can find food hard to find, and suffer high mortality rates as a consequence.

Particularly in extreme cold temperatures, with snow and ice making food difficult to obtain, a ready supply of nutrient-rich food on bird tables and bird feeders can literally be a lifesaver. Several studies have shown that supplementing the natural food supply increases the survival rate of many birds, particularly in harsh weather conditions.

Is feeding wild birds harmful to the birds?

An indicator of how well wild birds are doing generally are The State of the UK’s Birds reports published annually by various NGOs and government nature conservation agencies. You could assume that if feeding birds is generally harmful then those birds that use garden feeders would be doing relatively worse than species that do not. However, the most worrying declines seem to be from species that do not typically feed in gardens, such as seabirds and farmland birds, threatened more by food shortages and habitat loss or change. The most typical garden birds, such as Blue Tit, Robin, Blackbird and Chaffinch, all have positive breeding trends. Just the Starling, a bird that anecdotally seems to be doing well in gardens, shows a significant decline in the last 20 years.

Although this suggests that feeding birds doesn’t harm our common garden birds, it does also mean that we aren’t directly helping those birds most at risk. Hopefully the increased awareness of birds and the environment amongst those who feed birds would have a wider indirect impact though. Also, it is important to ensure that we only buy bird food and other products from companies that operate ethically for the environment.

Advantages and disadvantages of feeding birds

Changes to breeding behaviour and success rates

Birds require considerable energy throughout the breeding season. To produce eggs the female may use half of her stored energy whilst the male may be aggressively defending his territory and mate. When feeding young there can be high competition for available food supplies. After breeding, adults may be in poor feather condition and typically undertake a full moult. Supplementing available food by providing energy-rich food in gardens should therefore be beneficial, provided that it is clear that ‘artificial’ feeding does not lead to significant negative effects.

Various studies on different species have shown that feeding birds does affect their breeding behaviour, generally meaning that they may lay eggs earlier than normal, have larger clutches, heavier chicks and overall higher breeding success.

However, there are exceptions. One study by the Birmingham University Centre of Ornithology on Blue Tits and Great Tits showed that they did indeed lay earlier than normal, and had shorter incubation periods, but the clutch sizes were lower and fewer young fledged overall. The reasons for this are not clear. Maybe the diet was unbalanced and the birds were not getting the optimum nutrition required to produce high-quality eggs? Maybe increased winter survival led to more birds surviving to breed, but also including less fit pairs? Maybe the habitat was not ideal but provision of food had encouraged more birds to attempt breeding in the area? Overall it is not possible to conclude that the results of the study were negative: as well as the potential of more birds attempting breeding than normal, maybe laying and fledging earlier meant that individual pairs could actually raise more broods in a single season, outside of the study period?

In the summer, our hand-outs supplement the adult bird’s diet, reduces competition between birds and allows them to feed the young with more of the natural food that they are foraging for. After breeding many of the birds are in poor condition and will moult their feathers.

Unnatural food

Foods provided in gardens would often not form part of the birds’ natural diet, for example peanuts are not native to Europe, and many of the seeds provided would not be naturally found locally. However, few species of birds have reliable year-round food sources and are therefore opportunistic, seeking out whatever is available over sometimes long distances. Food we put out can be considered to be another supplement like much of their natural food. Birds in the garden will not exclusively feed on ‘artificial’ food either, but will take advantage of other food more naturally present, such as insects, spiders, worms and seeds direct from plants.

One nesting study of Blue Tits and Great Tits breeding in suburban gardens showed that only 15% of the food fed to their young was ‘artificial’. Thus, it is likely that adults directly benefit from the feed we put out, enabling them to more efficiently forage for natural food to feed their brood.

Dependency on bird feeders

Whilst birds will become accustomed to your bird feeders, few individuals remain in one garden for long. They may fly considerable distances daily, not just in the immediate local area, so are not dependent on one specific food source. Whilst they may be visiting other gardens and other bird feeders, they are typically also frequenting more natural habitats as well as foraging for natural food within the garden as mentioned above. There is little doubt therefore that bird feeders provide a supplement to the natural diet rather than primarily replacing it.

Especially in harsh weather birds will have a greater, if not exclusive, dependency on your readily available food. For this reason it is important not to abruptly withdraw feeding, for example if you are going away on holiday. In this case you should ideally find someone else to continue providing food in your garden or, in the worst case, gradually reduce the amount of food.

Disease transmission

Feeding birds in gardens can definitely increase the risk of disease transmission. The abundance of food and hence birds means that more sick birds will be present, and conceivably these may be present for longer periods if they are less able to roam elsewhere. A variety of species present in a small space means that pathogens will be able to transfer between individuals, and a build-up of droppings will also increase the risk of diseases spreading.

You may well notice possibly infected birds, which are often puffed up and lethargic. House Sparrows, Greenfinches, Chaffinches and Collared Doves seem to be the most frequently encountered sick birds in gardens, often suffering from Salmonella, E. coli or Trichomonosis.

To minimise the risk of spreading disease a good cleaning routine is required. Inviting birds to your garden is much like arranging a dinner party for friends: you wouldn’t serve poor quality food off plates you haven’t washed! That’s not to say the bird table and feeders need to go into the dishwasher daily, but they should be cleaned regularly. Take care also not to let food remain damp and accumulate mould such as Aspergillus which produces spores that can cause respiratory disease and be fatal to birds.

Equally you should be careful about the food you provide. For example, peanuts can carry the poison aflatoxin. Always buy from reputable suppliers.

If you notice any sign of sickness to birds or other wildlife in your garden, please do report it to Garden Wildlife Health, a project which is monitoring the health of British wildlife.

Increased predation

More food, hence more birds, means more bird predators. This of course is basic nature. In UK gardens the most obvious bird species to benefit from available small bird prey is the Sparrowhawk. Whilst it might not be nice to see one of your familiar sparrows become a meal for a Sparrowhawk, they have as much right to additional nourishment! Good populations of predators are generally a sign of a healthy environment so you may want to accept nature taking its course and enjoy the dramatic wildlife documentary taking place in your own garden!

However, if they realise there is an easy and ready food source they may visit much more regularly and take a sizable bite out of your garden bird population, literally. In this case, ensure there is plenty of native plant cover near your feeders for birds to escape to, and consider blocking easy flight routes to the feeders. You can always pause or reduce feeding temporarily: all birds will look for food elsewhere during this time.

Much more of an issue, however, are pet cats. The Mammal Society estimates that about 27 million birds are killed by cats in the UK each year. Whilst the RSPB suggests that there is no evidence for this causing a decline in bird populations overall when compared with more natural deaths, it is certainly something a garden bird lover would want to minimise. Some simple steps can make a difference, such as ensuring that cats wear collars with bells, keeping thorny plants under feeders and bushes where cats may hide, but the ideal solution is to keep cats indoors as much as possible.

Unwelcome species

Whilst not particularly an issue in the UK it has been suggested that feeding birds in gardens can encourage a disruptive and invasive species to the detriment of native, maybe shyer, species. For example, a study in New Zealand found that the native Grey Warbler became scarcer in gardens with bird feeders than without, whilst introduced birds such as House Sparrows, Spotted Doves and Common Mynas thrived. There was no confirmation of an overall population decline in the species though, and one possible reason for the local reduction was because of the type of food available, so it is important to provide food suitable for the species you want to attract.

Scattered and leftover bird food on the ground is likely to attract other animals, such as mice, rats and squirrels. This isn’t necessarily an issue, providing more food for predators such as owls and kestrels for example, but can be minimised by not overfeeding, and occasionally cleaning up the area. Overfeeding could also result in large flocks of unwelcome species, such as Feral Pigeons and Starlings, which can cause health issues due to a large build-up of droppings.

Window strikes

Collisions with windows are known to be a major cause of death for birds worldwide. In gardens the presence of feeders near the house can increase the risk of this, particular if birds fly off in a hurry when a predator appears for example. Whether these garden incidences are significant overall is doubtful, but it is easy to prevent birds flying in to windows anyway, e.g. by placing feeders further from the window and putting coloured stickers on the glass to make it more visible.

Human benefits of feeding wild birds

The benefit of humans simply enjoying watching wild birds should not be underestimated. With increasing urbanisation, children in particular experience and empathise less with the natural world. Urban birds provide the easiest wildlife experience and feeding them is immensely rewarding and educational. The joy caused by birds coming to you, and being seen at such close quarters, can engender a lifelong interest with the outdoors and nature. Providing feeders and different foods encourages a variety of birds and allows people to learn about their behaviour and needs throughout the seasons. It’s easy to see how this can expand to an understanding and appreciation of the importance of conserving the wider environment.

An interest in the different birds that come and go can also lead to getting involved in citizen science projects such as Garden Bird Watch which, whilst providing valuable conservation data in itself, can act as a stepping-stone to more serious scientific study.

A recent University of Exeter study showed that watching birds near your home reduces incidences of anxiety, depression and stress. There is no doubting the therapeutic benefits of birdwatching, especially for people with mental health problems, and the elderly and those with limited mobility

Consensus

Overall there may be some negative consequences to feeding birds in our gardens, but these would appear to be outweighed by the direct benefits to the birds, as well as the indirect benefit of increasing awareness and appreciation for wildlife and the environment. By developing garden habitats we can do our bit to help out, and compensate slightly for environmental destruction elsewhere.

There are certainly risks associated with feeding birds. It is important to feed responsibly, minimise the risk of disease through a simple cleaning routine, and attempt to keep those cats away!

Do you have further thoughts about whether we should feed wild birds or not? Please leave your comments below.