RZSS welcome bloodsucking invertebrates in time for Halloween

Posted: 31st October, 2023

This Halloween season, the Royal Zoological Society of Scotland (RZSS) is taking steps to help save another of Scotland’s threatened wildlife species – the medicinal leech.

Although some might say the species is less charismatic than others that the wildlife conservation charity cares for, medicinal leeches have played an important part in human history and now they need help.

Once widespread, medicinal leech populations have dramatically declined across Europe, particularly in the UK due to their historical use in medicine. Many of those taken from wild populations were used for bloodletting and those left today face threats including habitat loss and changes in land use.

RZSS is working with Buglife to safeguard the future of these tiny bloodsuckers as part of the Species on the Edge programme. Under license from NatureScot, staff from RZSS’s conservation team and Buglife took a trip to one of only three known lochs in Scotland that still have medicinal leeches, to source founders for the new conservation breeding programme.

Fourteen leeches were collected and are now in their new home in a specially designed facility at RZSS’s Highland Wildlife Park, where conservation team staff will care for them and attempt to breed as many leeches as possible to release back into the wild.

Dr Helen Taylor, conservation programme manager at RZSS, said, "Our wildlife conservation charity has been championing overlooked, threatened invertebrate species for a while, but this might be our biggest challenge to date in terms of getting people to fall in love with a species.

“Medicinal leeches have a fascinating history and form part of complex freshwater ecosystems, but people can be a bit grossed out by the whole blood-sucking thing.  They are certainly very different from any other animal we look after in the conservation department, but that just makes them more interesting.

“This is a species where individuals are both male and female at the same time, have a ‘brain’ in each of their body segments, can go without feeding for weeks, and live exclusively on blood. We are excited to be looking after such an unusual species, and to be helping secure a long-term future for them in Scotland through our dedicated conservation breeding and reintroduction programme.”

Craig Macadam, Conservation Director at Buglife, said “Medicinal Leeches have an important place in our medical history but are now one of the rarest invertebrates in Scotland. Conservation breeding was first suggested for this species nearly 30 years ago. It’s fantastic that the Species on the Edge project means that we can now take this important step to secure the future of the Medicinal Leech in Scotland."

This work is possible thanks to the Species on the Edge project – a major programme to help some of Scotland’s most threatened species. The conservation breeding of Medicinal Leeches is being made possible through the Helping Nature Fund, part of the Nature Restoration Fund. Managed by NatureScot, the Helping Nature Fund is an element of the Scottish Government’s flagship £65 million Nature Restoration Fund

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