Despite variable weather so far this spring, all it takes is a few days of warm sunshine for butterfly numbers to rocket. The British Trust for Ornithology’s (BTO) Garden BirdWatch results show that this is exactly what happened at the beginning of April, with new records reached for some species.

The numbers and time of year that butterflies emerge from hibernation is dependent on the weather, and this spring was no exception. Unsettled weather throughout March meant that reports of butterflies were much lower than in previous years. However, when a spell of dry, warm weather happened at the beginning of April the butterflies took advantage of it and reports shot through the roof.

Both Brimstone and Small Tortoiseshell butterflies were reported from about a quarter of BTO Garden BirdWatch gardens at the beginning of April 2014, but this year Small Tortoiseshell was seen in almost 40 per cent of gardens, a record for April, and Brimstone was seen in a third of gardens – the highest proportion of gardens since recording started in 2003.

However Peacock was the biggest surprise seen in over half of BTO Garden BirdWatch gardens compared to only a third in April 2014, and another record for butterfly reports in April. Sadly the good weather did not last, however, and reports of butterflies dropped off quickly.

Clare Simm from the BTO Garden BirdWatch team commented, "As you can see, the BTO Garden BirdWatch is not just about birds. Our volunteers provide us with vital information on other taxa too, helping us to understand how important gardens are as a habitat for all wildlife. If this unsettled weather continues, it may be bad news for butterflies so we need to keep an eye on how they fare over the rest of the year."

Was the short spell of sunshine in April enough for our butterflies, or will the unsettled weather affect their numbers this year? Help us find out!

To find out more about taking part in BTO Garden BirdWatch, including a free enquiry pack and magazine, please get in touch by emailing gbw@bto.org, telephoning 01842 750050, write to GBW, BTO, The Nunnery, Thetford, Norfolk, IP24 2PU or visit www.bto.org/gbw.