Surveys and DNA analyses reveal fascinating glimpses into the lives of Sheffield’s otters

Wednesday 20th September 2017

Otter, by Elliot SmithOtter, by Elliot Smith

The otter is one of our largest but most elusive native mammals. Two years of surveying the River Don for signs of otters, coupled with cutting edge DNA analyses has revealed new insights into the River Don’s otters.

The surveys were carried out through ‘Nature Counts’ – a two year partnership project which aims to monitor, protect and celebrate Sheffield’s wildlife. Nature Counts is coordinated by Sheffield & Rotherham Wildlife Trust, along with the University of Sheffield, Sheffield City Council, Sheffield Hallam University, Museums Sheffield: Weston Park, Sorby Natural History Society and Natural England, and made possible by money raised by National Lottery players through a Heritage Lottery Fund grant of £99,800.

Once believed to be the most polluted river in Europe due to the booming steel industry, the city has now cleaned up its act to support a startling array of wildlife, including the king of the river: the Eurasian otter. Since a massive nationwide population crash in the mid-century due to the use of organochlorine pesticides (PCBs), habitat loss and persecution, otters have been slowly making a comeback, and the River Don is no exception.

The Nature Counts team and its volunteers found otter droppings (spraints), footprints and feeding signs of this top carnivore at multiple locations, which suggests that stretches of the River Don are now in a suitable state to support an entire food chain.

Copyright Sheffield & Rotherham Wildlife TrustTo accompany the surveys, the team set out to capture footage of Sheffield’s otters through a network of video surveys. Using specially designed cameras that are triggered by heat and movement, the team have now captured several exciting shots of otters in urban environments (snap shots pictured).

The ‘Otterly Amazing’ team of specially trained citizen scientists searched over 24km of the river together with project ecologists, identifying signs and collecting over 100 otter spraints.

Otters spraint up to 20 times a day and field signs can indicate presence of otters and frequency of visits to sites. However, in order to learn about otter numbers, their sexes, distribution and diet, DNA analyses of the spraints are needed. These analyses were performed at the University of Sheffield by a team headed by Dr Deborah Dawson from the Department of Animal and Plant Sciences.

Despite the well documented difficulties of extracting DNA from otter spraints, the team was able to obtain genetic profiles revealing that seven otters passed through the study area during 2017, including at least two males. A female otter was detected at a separate location north of Sheffield. The DNA profiling was performed by Amy Withers, a visiting MSc student from the University of Leeds, who was jointly supervised with Dr Hannah Dugdale.

Dr Dawson’s team was also able to detect species on which otters were feeding. This work was performed by Dr Sabuj Bhattacharyya, a Commonwealth Fellow, who visited the lab from India, as part of a knowledge exchange program. DNA-based diet analyses revealed that otters on the River Don were feeding on fish, birds and amphibians. Smaller fish, such as bullhead, stickleback and minnow, were detected in the diet as often as larger fish. Microscopic analysis of spraints by Barry Soames, a volunteer with the Moors for the Future Partnership, identified crayfish to also be present in spraints, which is likely to be the invasive signal crayfish.

Sheffield & Rotherham Wildlife Trust and its partners intend to use the results to inform further conservation work and surveys in the north west of Sheffield as part of the Sheffield Lakeland Landscape Partnership project.

Sara Blackburn, Otterly Amazing project coordinator, said: “We were so incredibly excited to record the first video of an otter back in July 2016, and since then we’ve captured these elusive creatures no less than 22 times at numerous location across the city. We’ve also recorded some really interesting behaviour. What is most exciting is to see these amazing animals amongst a backdrop of industrial buildings - it really does show how the river has improved, even in the most industrial areas, and we hope that everyone is as pleased as us to see the return of otters to the Don.”

Copyright, Sheffield & Rotherham Wildlife Trust

David Renwick, Head of the Heritage Lottery Fund, Yorkshire and the Humber, said: “Few people realise that every National Lottery ticket has the potential to save the UK’s important species and wildlife, bats and bluebells are as important a part of our heritage as Botticelli. The Nature Counts project is helping to protect otters and other species for our future generations and to engage people with these fascinating creatures.”

Amy Withers, who performed the DNA profiling, said: “To be able to use genetic analysis to investigate otters on the River Don and learn more about this very elusive mammal has been amazing. Our results matched well with previous records of otter presence based on sightings and signs, but we were able to take this further to produce the first DNA-based estimate of otter numbers in this region. We were very excited to identify seven different individuals that had visited this part of the river during 2017.”

Dr Deborah Dawson, who led the DNA study, said: “We have been amazed by the public interest in our research, and delighted to receive so many questions at the ‘Sheffield’s Otters’ event. It is fantastic that otters are recovering and returning to their historical ranges. Numbers are still low and recovery has been slow, especially in the North of England, but we hope our DNA study has shown a new and more accurate way to monitor otter numbers, map their recovery and learn more about the movements, diet and behaviour of this elusive creature. We hope that the multiple new developments along the River Don are done sympathetically to ensure habitats and connectivity are preserved for wildlife to thrive and the public to enjoy.”

Dr Nicky Rivers, the Living Landscape Development Manager at the Wildlife Trust added: “If people are keen on finding out more about otters in the region then there are a number of ways in which they can learn about them, including the Nature Counts display at Western Park Museum. Otters are a protected species and can be very easily scared away from the area by even the most well-meaning people, so if anyone is interested in looking for signs of otter they should do so through citizen science projects, such as a new survey by our neighbours Moors for the Future Partnership.”

Both the survey results and DNA findings were showcased to a sold out event at Sheffield University’s Firth Hall on Tuesday 5 September with over 300 attendees.To find out more and view the otter video footage go to wildsheffield.com/otterly-amazing or visit the Nature Counts exhibition at Weston Park Museum. The Trust’s video footage will be available soon on the same page. To read more about the University of Sheffield’s Otter DNA study, go to sheffield.ac.uk/molecol/deborah-dawson/sheffieldsotters.