There are fewer blue tits this year according to the BTO’s Garden Birdwatch survey.
By: Phil Pickin
Tags: Nature Conservation, Birds, Conservation, Wildlife, Nature

Blue tit © Phil Pickin

The British Trust for Ornithology (BTO) has, for the last 25 years, run the Garden BirdWatch survey in which participants submit their records of garden birds to help the trust understand how these species are faring. The lockdown has allowed many people to reconnect with nature and participate more than ever, but evidence from survey has shown that some of our favourite garden species, such as the blue tit, have been struggling this year. The BTO think this is possibly due to the unusually warm spring.

The BTO have pointed out that, “this year’s spring, with the fifth-warmest April in over 100 years, meant that invertebrates, including butterflies and moths, got off to an early start. Caterpillars are an important food for blue tit nestlings, but in warm springs caterpillars develop early, and there are fewer available during the main blue tit nesting season, often leading to reduced survival of nestlings and smaller populations overall.”

Survey results show that blue tits were seen in 5% fewer gardens this August, with only 80% of gardens reporting these colourful birds when we would normally expect to see them in around 85%. If a similar trend is seen across habitats, this could mean the UK is entering winter with over half a million fewer Blue Tits than a typical year. While this gap had closed somewhat by October, they are still being recorded in fewer gardens than is typical for autumn.

As we all know, blue tits are one of the most common garden birds, being reported in around 94% of gardens during the winter months and will often be seen visiting garden bird feeders. They are also one of the most regular users of nest boxes. We have one roosting in a nest box every night at the moment. The BTO are keen for us to keep an eye on how Blue Tits fare in gardens for the rest of 2020 and into 2021. If, as is expected, 2020 has resulted in a poor breeding season this often means that the remaining birds are more likely to survive over the winter. The reason being that there is less competition for resources, meaning the population corrects itself, but the BTO need to keep monitoring numbers to find out.

The Trust have also said that another common garden species, the Great Tit, has also been seen in fewer gardens, and have also likely been affected by the availability of caterpillars. Lower numbers of other insect-eating species has been seen during the same period of time. Pied Wagtails and Wrens may have also struggled due to a possible lack of available caterpillar food due to the early spring. Both species saw their reporting rates fall below average after June when we would normally see young birds emerging.

However it’s not all bad news. Long-tailed Tits, a small, with their long “lollipop” tail, had a reporting rate higher than usual from May onwards, implying that these birds have had a successful breeding season.

The BTO’s Garden BirdWatch saw a large increase in participants during lockdown in March and April as the scheme became free to accommodate a growing interest in garden wildlife as many people had more time to enjoy their garden birds.

Robert Jaques, Garden BirdWatch Supporter Development Officer at the BTO says “Thanks to the records submitted by our dedicated Garden BirdWatchers, we are able to see the impacts of weather events on garden birds. We will be watching with a keen eye over the coming months to see how Blue Tits, and other garden species, handle the next winter.”

BTO’s Garden BirdWatch is a weekly wildlife survey which has been running for 25 years, with 20,000 active members. Through the survey BTO scientists have been able to see the changing fortunes of garden wildlife, helping to understand how gardens can be made friendlier and more beneficial for wildlife.

For more information, please visit www.bto.org/gbw