On the island of Craigleith, puffin numbers crashed from about 10,000 pairs to less than a thousand, due to a giant invasive plant called tree mallow which grows to 3 metres in height. Tree mallow also spread onto the nearby islands of Fidra and the Lamb and threatened the puffin populations there as well.
Tree mallow is thought to have been introduced to the Bass Rock over 300 years ago by soldiers manning the fortress there because of the medicinal value of its leaves. It has spread rapidly in recent years, helped by mild winters (linked to climate change), taking over other islands and preventing the puffins from nesting and rearing their young.
Over 330 work parties have made regular trips to Craigleith, Fidra and the Lamb over the last 14 years to cut down the tree mallow. The project is run by and supported entirely by volunteers many of whom come back repeatedly to help on work parties. Over 1,300 volunteers have been involved since the project began.
Thanks to all the volunteers’ hard work, excellent progress has been made and tree mallow has been brought under control. Monitoring is showing that the natural vegetation is recovering and the puffins are now able to nest without interference from tree mallow. Other nesting birds such as eider ducks and fulmars have also benefitted. The project will need to continue for some years as tree mallow carries on regenerating from the large seed bank in the soil.