Road deaths decimating Shetland’s otter population

10% of Shetland otters are killed by cars. Credit SNH

10% of Shetland otters killed by cars
December 2009. Figures from Shetland show a significant increase in the number of otter deaths reported in recent months compared to previous years. This year's rising death toll may already account for as much as 10% of the islands' total otter population with 95% of the recorded deaths confirmed as road casualties. Scottish Natural Heritage is asking Shetland motorists to keep a watchful eye out for otters as they drive around the islands this winter.

SNH Area officer Glen Tyler said: "Given the increase in deaths this year we're asking drivers to be aware of the locations where otters may be encountered such as coastal roads and places where roads cross water courses. We ask that extra care is taken at these sites, especially during the dark winter nights. Each year we expect to receive around 13 dead otters but this year has seen a big increase with the Shetland office collecting 21 corpses to date. The true number killed is most certainly even higher since not all casualties are reported to us and collected for autopsy."

October - December is worst time for otters
"Most otter road deaths happen from October to December and usually coincide with darkness around rush-hour involving young otters seeking new territories. These energetic mammals often dart across roads near water and sadly many are killed each winter in road accidents as motorists are taken by surprise by their sudden appearance. Unfortunately the strong legal protection afforded by the Habitats Regulations, while saving them from deliberate harm and disturbance, does not prevent their accidental death on the road."

500 otters on Shetland
SNH routinely collects carcasses of dead otters and sends them to the University of Glasgow Vet School for autopsy. With a population of perhaps around 500 adults this year's death toll may approach 10% of the population.

These energetic mammals often dart across roads near water and sadly many are killed each winter in road accidents as motorists are taken by surprise by their sudden appearance. Credit SNH

Since 1981 SNH have received 392 corpses of otters, mainly road casualties, which are sent to Glasgow for autopsy examination and possible post mortem. Ironically autopsy examination is a very good way of measuring ‘health' of the population as it provides information on age, sex and breeding status of animals as well as data on pollutants and cause of death.

Internationally important population - Large declines
The internationally important otter population in Shetland is monitored by the renowned otter specialist Jim Conroy at a sample of sites in northern Shetland.

The study has lasted for more than 30 years and for much of that time has been supported by BP. The observed trend from those sample areas is that the population declined from an estimated peak of 1000 otters in Shetland in the 80s and early 90s to a low point in the mid 1990s. By 2001 numbers had recovered close to the peak of the previous decade but the most recent surveys suggest there has been a significant population decline of more than 50% from 2003 with no sign of a recovery since then.

Significant reduction in the availability of prey
Jim Conroy says: "The decline in otter numbers is most likely caused by a significant reduction in the availability of the animals' main prey, small inshore fish. This has been reflected by an increase in the amount of crab in the diet immediately before and during the decline periods. Despite the fall in otter numbers, Shetland still has a high density of otters, and the chances for people to view them are as good in Shetland as anywhere."

SNH would like to know if you see any dead otters in Shetland. The local area office can be contacted on 01595 693345, or by e-mail at Northern_Isles@snh.gov.uk