Evolution MegaLab


Scientists have been studying the banded snail for many years and have found that the darker shell types tend to be more common in woodland where the background colour is brown, while in grass banded snails tend to be lighter-coloured, yellow and more stripy. This variation is thought to be adaptive, at least in part providing camouflage.

Birds eat banded snails

We want your help to find out whether predation by birds is still important, because there has been a big decrease in the numbers of song thrushes in some places over the last 30 years. If there are fewer song thrushes about, you would expect the different snails to be less faithful to their particular habitats than they used to be.

Climate change

There is also a geographical pattern in the colour of shells that we think may have changed in response to the warming of the climate over the last 30 years. Darker shells used to be more common in the north than in the south. We think this was because darker shells warm up more quickly in sunlight, enabling the animals to be more active than light-coloured snails in colder areas.

Help us find out whether lighter coloured shells are more common further north than they used to be, now that the climate has become warmer.


This project was launched in 2009, but data are stil being collected. The results of the first two years' of data collection have been published in this paper: Silvertown, J. et al. (2011) Citizen Science Reveals Unexpected Continental-Scale Evolutionary Change in a Model Organism. PLoS One, 6, 8.