How does climate change affect garden birds?

The RSPB's Conservation Scientist Daniel Hayhow discusses climate change and garden birds.

Our climate is changing. 2019 was the Earth’s second warmest year since modern records began in 1880. The average UK temperature has increased roughly 1deg C since the 1960s, leading to warmer and wetter winters, and the evidence is growing that changes in our UK climate are affecting our birds. 

The effects on birds can be anything from where they occur, to when and how breeding and migration takes places. It can even impact the amount and timing of food available and our garden birds are no exception, with climate change affecting even the species which visit our bird feeders. 

Some birds may have benefited from climatic changes, being found in more places or increasing in numbers, in northern parts of the UK where winters have generally warmed. As an example, Big Garden Birdwatch data found that great tits recorded in gardens have increased across the UK by 8% over 10 years. This increase has been mostly in Scotland (13%) compared to the usually-mild south-east of England (3%).

Warmer winters can greatly benefit smaller birds such as this great tit (c) Grahame Madge (rspb-images.com)

Goldfinch are also on the rise with the numbers recorded in the Big Garden Birdwatch increasing by 71% since the early 2000s. It only entered the top 10 for the first time in 2008 – with a particularly noticeable increase in North Scotland where they were recorded in more than double the number of gardens. 

Nuthatch, one of our less common gardens visitors, has extended its range northwards and now occurs in more gardens in the south of Scotland than previously. These changes, for both goldfinch and nuthatch, are possibly due to both warmer winters and an increase in the number of people putting out food. 

Migration patterns 

Climate change is a global phenomenon, and changes experienced by migratory birds elsewhere can affect who turns up in our gardens. You may have even noticed it yourself when the swallows and house martins return. In response to warmer spring temperatures, birds including swallows, willow warblers and chiffchaffs, are arriving back in the UK up to two weeks earlier than they did in the 1960s.

House martins and swallows are just some of the migratory birds which are being affected by climate change (c) Nick Upton (rspb-images.com)

Some birds have also started laying their eggs earlier in the year, including chiffchaffs, willow warblers and resident great tits. Although the ability to adapt and change is essential for a species to survive a changing environment, this still depends on food and habitat being available at the right time. If insect food isn’t around for parent birds to collect, that could cause fewer chicks to reach adulthood.  

The milder winter on the continent this year means that we have seen fewer species like brambling, redwing and fieldfare in our gardens – these species come in large numbers to the relatively milder UK when conditions are particularly tough on the continent. Indeed, we know from bird recording that there was a large concentration of brambling in southern Scandinavia in January suggesting that they did not need to seek out better conditions on our shores. 

An uncertain future 

While some bird visiting our gardens may have benefitted to some extent from climate change, the impacts on some other species in the UK have been far more harmful, especially on our seabirds and upland birds. For example, climate change has been linked with changes in the availability of small prey fish, which is related to breeding failure in some seabirds.  

It is also important to remember that any changes to our climate in the future are likely to be much greater than we have already experienced to date, which may not continue to be beneficial for birds visiting our gardens. This combined with a pattern for more extreme heavy rainfall in winters and drought in summer, mean that the future may be more difficult for many species. 

How you can help 

We know that our gardens, and the food we put out, provide a fabulous resource for birds. There are lots of ways that we can ensure that our gardens are resilient and continue to provide places for birds and other wildlife to feed, shelter and to breed in a changing climate. 

Putting out food for birds helps whatever the season (c) Rosemary Despres (rspb-images.com)

Wildlife-friendly gardens are a fantastic habitat which allow animals to quickly travel through unsuitable areas.  This connectivity is something that has been shown to be important under climate change in the wider countryside across the country, for example the amount of woodland in a landscape for birds or wide expanses of wildflower rich habitats for butterflies. So, it is great to think that we can play just a small part in that by providing great diversity and habitats in our patch of garden, however small!