One of the rarest invertebrates in Scotland, the Medicinal Leech (Hirudo medicinalis), has been confirmed in Dumfries and Galloway for the first time, after a recent sighting was verified by Buglife this September.
The sighting came from local naturalist, Bob Merritt, and follows unverified records from 2005 and 2008. Buglife confirmed the presence of the Medicinal Leech in three ponds near Carrick Shore on the Solway coast, as part of the Scotland-wide conservation programme, Species on the Edge.
Medicinal Leeches can grow up to 20cm long making them one of the UK’s largest native leeches. They can be found in a variety of freshwater habitats, including ponds, lochs, ditches, wetlands, and streams. In Scotland, Medicinal Leeches have a dark brown or black upper side with yellow-grey stripes and a speckled underside. They feed on blood from cattle, deer, amphibians, fish, and birds, and only feed every 3 to 12 months. They can live up to 20 years.
Once widespread, the Medicinal Leech is now known in only three areas in Scotland – mainland Argyll, Islay, and now Dumfries and Galloway – having suffered severe declines primarily due to historical overharvesting for use in medicine. In the late 18th to early 19th century, millions of these leeches were used in hospitals across Europe for bloodletting treatment. While medical exploitation of the leech is now illegal in the UK, habitat loss and freshwater pollution have badly affected Medicinal Leech populations in Scotland.
Buglife Conservation Director, Craig Macadam, said “Medicinal Leeches have an important place in our medical history but are now one of the rarest invertebrates in Scotland. The discovery of three new sites for this species in Dumfries and Galloway is incredibly important and gives us hope that further sites are discovered for this incredible species in the future.”
As part of the Species on the Edge programme, Buglife is working with the Royal Zoological Society of Scotland (RZSS) to deliver Scotland’s first ever Medicinal Leech captive breeding programme. In an effort to save the rare leech from extinction in Scotland, 14 leeches have been collected from one of their known sites and transferred to their new home – a specially designed facility at RZSS’s Highland Wildlife Park. There the conservation team staff will care for them and attempt to breed as many leeches as possible to then be released back into the wild.
Fiona Strachan, Species on the Edge Programme Manager with NatureScot said “These records from one of the Species on the Edge project areas are really exciting and, alongside the captive breeding programme, bode well for a more promising future for the Medicinal Leech.”
If you see a large leech in Scotland, please take a photo and send your sighting to Buglife at email@example.com. Please note they are rare and protected, so if found attached to waders or wetsuits please gently brush them off and return them to the water.