Trialling hogweed munching sheep

The Scottish Invasive Species Initiative (SISI) and the Gordon family of Kirkside Farm, Macduff are working in partnership to trial an innovative, sustainable method of removing invasive giant hogweed plant from a wooded area of the farm – a flock of hogweed munching sheep.

Invasive non-native species have a significant negative impact on our environment - they are identified as one of the five greatest direct drivers of nature decline. Giant hogweed is one of the worst offending invasive species, it can grow to a massive 5m tall, form dense, impenetrable stands and outcompete all nearby plants. Its photo-toxic sap burns the skin of anyone who touches it and so is a serious hazard for walkers, anglers and anyone trying to enjoy the countryside.  Removing these invasive plants thus enhances the environment for both wildlife and the people enjoying it. 

The trial project at Kirkside saw the introduction of a flock of 25 sheep in April 2019 into a 10ha site of woodland overrun with giant hogweed alongside the River Deveron.  The giant hogweed on this site was impacting both on the woodland and its biodiversity and with a footpath running through the wood, posing a hazard to walkers and dogs.  To succeed, the project also requires the ongoing cooperation of the local community to act responsibly and keep dogs on leads when the woodland is being grazed which, following awareness raising work, they are doing.

The sheep are now settled into their new home and eating all the giant hogweed leaves. Giant hogweed will only flower when mature (after 3-4 years) and has sufficient energy reserves. The grazing itself is not killing the hogweed but prevents it from flowering and, so producing seed.  This stops the spread of the invasive plant from happening. 

In comparison the standard method of giant hogweed treatment is application of herbicide, a method used at Kirkside Farm over the previous two decades. However, due to the difficult terrain and scale of infestation, this method failed to control the hogweed. It was also costly, damaged nearby native flowers and required the ongoing use of chemicals - something the Gordons were keen to reduce.

Monitoring of the site and the hogweed grazing is being undertaken in partnership with the University of Aberdeen. The trial, which will continue for several years, aims to produce practical advice for land managers on the use of livestock as a method of controlling invasive plants - enabling others to use this grazing control method and reduce chemical use. The partnership with the Gordons and their farmer’s perspective is critical and makes this a real-life learning experience with practical application.

The project and partnership will provide immediate benefits to the local environment at Kirkside Farm. However, it’s research and management outcomes will have far reaching implications in providing a more environmentally friendly, sustainable method of invasive species control to the wider land management community.  This will ultimately benefit our special native species, the wider environment and the people who use and enjoy it.