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The Big Picture
How feeding garden birds has changed the pecking order

Abstract

Bird feeding in gardens has increased over the past 40 years and, as Georgina Mills explains, this has had a huge impact on the diversity of birds visiting UK gardens

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It is fascinating to discover how this seemingly smallscale hobby is restructuring bird communities

The increase in bird feeding in UK gardens has changed the composition of bird species over the past 40 years, new research has found.

By providing food, particularly in winter, the habit of feeding birds has led to less competition for food and more diversity in our gardens.

The study, which was published in Nature Communications, first looked at changes to bird feeding habits by the UK public. By looking at advertising in a popular birding magazine, the researchers found that not only had advertising for bird feeders and feed increased exponentially, but the diversity of foods available had too. This indicates a rise in the popularity of feeding wild birds. In the UK alone, some reports suggest the public spends up to £300 million a year on specialist birdfeed products.

The research, carried out by the British Trust for Ornithology (BTO), then looked at figures from the Garden Bird Feeding Survey (GBFS), which has been collecting data from budding birders since the 1970s. It asks people to note down which birds they see in their gardens at a particular time in the year to create a picture of the diversity and populations of birds in the UK.

The researchers found that in the 1970s approximately half of the birds visiting garden feeders belonged to just two species. However, 40 years on, the number of species making up the same proportion of the community had more than tripled.

As no significant change was noted in the distribution and range of the birds over this time, this may suggest the increase in bird feeding could be responsible for attracting more individuals to visit gardens. Data from the GBFS also showed an increase in the number of feeders and diversity of foods being given over time.

An increase in feeders has led to a change in the hierarchy in gardens, the researchers believe. With more food available, different species are able to avoid competition and ensure they have enough food.

The researchers acknowledge that changes to populations could be a result of various factors, including climate change, resource availability and predation. However, feeder use was reported to have increased by around 15 per cent between 1972 and 2012 for 39 specific species that regularly visit garden feeders.

Individual species that were rarely seen in the 1970s are also now commonplace in gardens – species such as the goldfinch, the greater spotted woodpecker and the wood pigeon have increased over the time period studied.

There are a few species that have decreased over time too, such as the song thrush, the starling and the marsh tit.

Lead author Kate Plummer, a research ecologist at BTO, said: ‘We now know that garden bird feeding is one of many important environmental factors affecting British bird numbers. It is fascinating to discover how this seemingly small-scale hobby is restructuring bird communities across large spatial scales.’

If feeding continues to intensify as it has done, the increase in numbers and diversity will continue, the researchers say. However, the negative impacts of feeding must also be borne in mind, such as increased disease transmission at feeders, and the potential poor nutritional quality of some food supplements.

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