otter © Darin Smith

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The variety of life

The recovery of the otter

Following a catastrophic population crash in the 1950s this is undoubtedly a conservation success story. However, we shouldn’t get too complacent, warns James Field, North Somerset Levels and Moors Biodiversity Officer.

Back in 2000 the North Somerset Levels and Moors Project set up the North Somerset Otter Group (NSOG) to discover whether otters had really returned to the county. The project uses a network of volunteer surveyors who, every quarter, search for otter field signs alongside selected watercourses.

Spraint spotters
The most common sign that an otter has visited is otter droppings or “spraint”. Otter spraint contains a cocktail of scented chemicals that otters use to communicate with each other and establish territories. It is usually deposited at prominent points alongside a river and has a distinctive, sweet and suprisingly not unpleasant smell. Other signs of otter presence can include footprints or the leftovers from their last meal.

We now know that the answer to the question “have otters returned to North Somerset?” is undoubtedly an emphatic and welcome yes! Otter signs have been discovered along major watercourses throughout the county and the situation certainly look encouraging. Nationally the picture is also looking very encouraging with otters returning across much of their former range. An otter was recently spotted swimming in Bristol harbour.

Why worry?
So why my cautious introduction to this article? Surely the Champagne corks should be popping? Well, for a start we can only hope at best to get a very rough indication of the status of our otter population through standard survey techniques. All a spraint tells us is that an otter has visited a site at some time in the recent past and not how many otters are active in the area. Five spraints in an area could represent five separate otters or one very busy otter. However, this is not to underestimate the value of such work. The NSOG was recently treated to a presentation by James Williams from the Somerset Otter Group. James showed how his Group, which has been established since the 70’s, was able to show the gradual return of otters to sites across Somerset over the last quarter of a century. However there was also cause for concern as their figures for the last couple of years suggested a notable decline in otter activity across the county. This included a 40% reduction in otter visits to two regularly monitored sites. In addition there has been a mysterious, significant increase in the number of otter deaths (mostly reported across the south west during the last year). Post mortems carried out on those otters have shown that they have fewer bite marks on them. This is attributed to territorial fighting, a normal part of otter behaviour, indicating that there is less interaction between adult
otters due to them living at lower densities.

Cause for concern
The reason for this apparent decline is not yet understood but in 2005 a parasitic bile fluke was found to be infecting otters in Somerset. After further investigations it is thought that it originates from Eastern Europe from where it was introduced to the UK in imported ornamental fish stocks. The overall impact of the fluke is still poorly understood but it is known that it can cause liver damage and jaundice in infected otters. The parasite’s known range is also expanding as more otters are being autopsied. In January of this year a dead otter was discovered at Blaise Castle in North Bristol and was discovered to contain the most northerly record of the parasite in the south west. It has also been discovered in Norfolk and Cambridgeshire. Also of concern is the declining eel population in our rivers recorded in recent years. The eel is a staple in the otter’s diet and there is already evidence to suggest that otters are turning to alternative food sources, such as nesting waterfowl, as it becomes harder for them to for them to find eels.

Whilst it is fantastic news that otters have made such a comeback it is vital that we don’t get too complacent. Otter populations have crashed in the past and could do so again. They reproduce slowly with most otter bitches struggling against the odds to rear only a few kits (juvenile otters) to adulthood in their lifetime. Any factor, or combination of factors, which significantly lengthens those odds could have disasterous consequences for our rejuvenated otter populations.

Can you help?
It is more important than ever that groups like NSOG and the Somerset Otter Group continue to collect data about our otters. With this in mind the NSOG has recently changed the way it works so that it now regularly surveys a minimum of 70 sites covering 100kms of watercourse. To find out more about the North Somerset Otter Group or to become involved in otter surveying contact James Field on 0117 917 7270 or e-mail jamesfield@avonwildlifetrust.org.uk.

The North Somerset Levels and Moors Project
The North Somerset Levels and Moors Project is a partnership between the Avon Wildlife Trust, the Bristol Regionalal Environment Records Centre, Natural England, the Environment Agency, and North Somerset Council.

The Project was established in 1996 and aims to safeguard and enhance the important natural heritage of the North Somerset Levels and Moors area. It does this by working in partnership with landowners and managers, undertaking survey and monitoring projects and working with the community and wider public to raise awareness of this unique landscape. It is a lead partner in delivering the Avon and North Somerset Biodiversity Action Plans.