Bird Feeding – How is it Affecting our garden populations

Bird Feeding – How is it Affecting our garden populations

Supplementary bird feeding has increased rapidly since the 1970s, estimates suggest that up to 43% of households in the USA and 75% of households in the UK regularly feed wild birds, spending US$188–226 million (£148 – 178 million) (R 2206 – 3369) on 60,000 tons of bird seed annually. That’s a lot of food being made for bird feeding around the world.

Bird Feeding
Blue Jay

What’s all the fuss about feeding birds?

So firstly, why do so many people love feeding birds ? I read up about this and found that observing garden birds may provide people with a feeling of being connected to nature, contributing towards an increased sense of belonging in the natural world. How a person relates to nature has been shown to be a strong forecaster of environmental attitudes and has been positively connected with reduced anxiety and better mental health. Many people feel connected to their birds and are motivated to learn the best feeding practices.

There is increasing evidence that some people are more orientated towards interacting with the natural world than others, and are willing to invest more to obtain this interaction even when they have a reduced opportunity for doing so.

Bird Feeding
Cape White Eye

Observing birds at feeders and listening to their songs provide opportunities to reinforce a connection within one’s own garden. A bird feeder has the potential to be a powerful tool for people to make this connection, because it can provide a central location where people are able to observe birds and their behaviors.

Some of the locals at the restaurant

What are the affects of bird feeding?

The benefits for feeding birds may include reduced time foraging or enhanced body condition, which in turn may increase breeding success or survival and lead to population level changes. A better accessibility of food may artificially enlarge the carrying capacity of the urban environment, resulting in higher concentrations of species capable of exploiting supplementary food resources.


I have read that birds using these extra food sources are using them as supplemental sources and are not dependent upon them for their main nourishment. However, there may be negative effects for some individuals exploiting supplementary food sources because of, for example, increased disease transmission and malnutrition, which may lead to reductions in overall population size.

Another aspect which changes is that birds that have never interfered with each other are now facing off against each other. New hierarchy’s are developing and are largely driven by variation in body mass or size. A species’ position within the hierarchy can influence food choice and foraging tactics. More dominant species are significantly more likely to use the high value food option, compared with less dominant species.

My personal observations of feeding birds

While feeding the birds recently I found that 12 species visited my bird feeder regularly. The amount of time it took the birds to finish the food on the table was around two hours. Another interesting observation I saw was sparrows eating fruit when all the seed had been eaten. This was strange as they are predominantly granivores (seed eaters). Possibly an adaption to survive the leaner months. In regards to the liquid feeders, I only saw a sunbird once or twice and it was more interested in the flowers than the supplement I had put out. All the other birds that came to the garden however thought that the sugary concoction was great. I spoke to a researcher in this field to find out if these liquid feeders were good for sunbirds .

Her advice is –

To plant locally indigenous bird-pollinated plants (usually red/pink/orange/yellow-coloured, tubular flowers) in your garden since these provide food even when the humans aren’t home. If you plant a diversity of species that flower in different seasons then you can provide a continuous food source for sunbirds. However, I don’t think sugar water feeders are necessarily bad. Other than sugar and water, there are only trace elements of amino acids in natural nectar, so a plain sugar solution is a good food source for sunbirds. It probably does help the birds through the dry seasons. It is however very important to use only normal sugar (sucrose) and no artificial sweeteners. Xylitol, for example, is lethal to these birds. Feeder bottles and perches should also be cleaned with hot water or an environmentally friendly detergent to avoid the spread of diseases. You can avoid attracting bees, which often drown in the feeder bottles, by using feeders with a narrow entrance that only allow access to a bird’s tongue.  For example just cover the big opening with a piece of plastic or something with a small circle in it.

Dr Aina Coetzee
Bird Feeding
Liquid sugar water bird feeder. Mostly used for humming birds and sunbirds

Ive seen many pre made solutions for nectar feeding birds in the shops is called Ruby sunbird nectar. I also found a great link on how to feed hummingbirds for the American folk –

Disease Transferal due to bird feeding

The four diseases which are common in wild birds (there may be other more common diseases depending on where you live in the world) are conjunctivitis (pink eye); avian pox; fungal skin disease; and cloacal (the reproductive parts of the bird) infections. In research done in North America over 3 years, 81% of occurrences were avian pox, 8% were conjunctivitis, 6.3% were cloacal infections, and 4.7% were fungal skin disease. Uncleaned bird feeders significantly influences the health of birds in central USA and all over the world for that matter. Regular feeder cleaning may decrease disease transmission.

Any method that reduces density but not diversity, which may therefore reduce disease transmission, would be a worthwhile endeavour for bird-feeding hobbyists who want to lessen negative impacts of feeding while maintaining the species composition of their bird communities at feeders. Conservation organizations should also provide people who feed birds with information on how to clean feeders and its importance in an effort to reduce disease occurrence at feeding stations.

Great Tit

This entails a time investment and because home owners often cannot see the effects of disease transmission it may have little observable effect. Therefore people who clean feeders can be viewed as showing an increased concern for bird health. It’s been found that only 58% of people regularly wash their feeders.

Invasive vs Indigenous Species

When people where able to cross oceans and explore different continents they brought birds with them. Due to having no predators these birds thrived and multiplied. In South Africa alone, I can name four such species. House sparrow (Passer domesticus) from Europe , European/Common Starling from Europe, Mallard Duck from Europe and the Common Myna from Asia. Thanks Europe but you can have your birds back now. I’ve also seen European Starlings in North America. The ring-necked parakeet (or rose-ringed parakeet) Psittacula krameri, is one of the most widely introduced in the world. This bird originates from India and Africa and has established populations in at least 35 countries. I’ll talk specifically about Parakeets but the same general rules apply to most alien invasive birds around the world.

The Parakeet’s aggressive behaviour may induce competitive advantages such as access to greater amounts of food and may indirectly cause a lower fitness and individual physical condition for the native species. It can be said that the lighter the species, the more ‘‘bullying’’ the ring-necked parakeet is. Parakeets initiate and win the interactions in most of the cases. The ring-necked parakeet being a gregarious species, can be expected to have stronger competition between these species and the native species over the next few years. Alien birds also out compete native birds for nest sites.

Bird Feeding
Ringnecked Parakeet

Take home Message

I think we can see from the above information that there are pros and cons for feeding wild bird populations in our gardens. The amount of food being put out for the birds across the world is huge. It has changed the dynamics of bird behavior, increased spread of disease and even changed some bird’s beak structure.

On the other side of the spectrum, the birds are healthier, they are having more chicks which boosts the populations. At the end of the day I think it’s good to feed the birds as long as its healthy food and you regularly clean your feeders. However if you notice that the majority of visitors eating at the feeders are alien species (like I have at home ) then I recommend not feeding these birds as this just aids the alien species to increasingly push out the indigenous birds. For more information about birding for beginners check this link out Happy Feeding. 

Bird Feeding
Red Cardinal


Coetzee A. 2019. Personal communications on sunbird supplementary feeders.

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