Garden butterfly boom

01 Nov 2013 | No. 2013-52

After a run of dismal summers, not to mention a late start to spring this year, our butterflies were sorely in need of a spell of dry, warm weather. Thankfully this summer delivered and results from the British Trust for Ornithology’s (BTO) Garden BirdWatch weekly survey, show that many species recovered spectacularly.

The late spring delayed the emergence of many garden butterflies, producing sharp peaks in activity rather later into the year than is usual. Many species were present in numbers well below what would more normally be seen in the Garden BirdWatch figures for early summer and BTO researchers were initially uncertain as to whether this would be another bad year for butterflies.

However, the summer soon turned into a glorious one and many butterfly species responded with sudden and dramatic increases in numbers. There were barely any Meadow Brown butterflies seen in Garden BirdWatch gardens at the end of June – the start of their usual flight period – but by mid-August they were reported in almost 25% of gardens. This is up 56% from last year, which is excellent news as the species has been declining nationally. Small Tortoiseshells had a less dramatic increase but were still seen in 46% more gardens this summer than in 2012.

The most impressive story of the year, however, belongs to the Peacock. This species overwinters as an adult, and was slow to emerge this year, with activity initially peaking about three weeks later than normal. However, once the weather improved and the first brood of the summer started to emerge, it did much better than in recent years. At the end of July, only 3% of Garden BirdWatch gardens had reported Peacocks but by the end of August, there were reports from 47% of gardens, which was 68% up on what was recorded in 2012.

However, as Clare Simm, from the Garden BirdWatch team, explains, not all butterflies experienced a good breeding season. "Whilst Summer 2013 was successful for many butterfly species, for some species the reporting rate from gardens was much lower than in 2012. These included Red Admiral and Holly Blue, species whose numbers can fluctuate quite dramatically from year to year because of factors such as the size of parasite populations."

She added: "As you can see, the BTO’s Garden BirdWatch isn’t just about birds. Our participants provide us with vital information about other wildlife too, helping us understand how important our gardens are as a habitat for all wildlife."

To find out more about the BTO Garden BirdWatch, ask for a free information pack which includes a copy of our quarterly magazine. Email gbw [at], telephone 01842 750050, or write to GBW, BTO, The Nunnery, Thetford, Norfolk, IP24 2PU.

Notes for Editors

  1. The BTO Garden BirdWatch is the only nationwide survey of garden birds to run weekly throughout the year, providing important information on how birds use gardens, and how this use changes over time. Currently, some 14,500 people take part in the project. The project is funded by participants’ contributions and is the largest year-round survey of garden birds in the world. For more information see
  2. The BTO is the UK's leading bird research charity. A growing membership and up to 60,000 volunteer birdwatchers contribute to the BTO's surveys, collecting information that underpins conservation action in the UK. The BTO maintains a staff of 100 at its offices in Thetford, Stirling, Bangor (Wales) and Bangor (Northern Ireland), who analyse and publicise the results of surveys and projects. The BTO's work is funded by BTO supporters, government, trusts, industry and conservation organisations.

Contact Details

Clare Simm
(GBW Development Officer)

Office: 01842 750050
(9am to 5.30pm)
Email: clare.simm [at]

Paul Stancliffe
(BTO Media Manager)

Office: 01842 750050
(9am to 5.30pm)
Mobile: 07585 440910 (anytime)
Email: press [at]

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