Otters

Regularly voted the nations favourite mammal, but how many of us have seen a wild one?  My interest in Otters has lasted over 30 years.  As a student I volunteered at an Otter sanctuary in Derbyshire and it was here I got to admire this skilful semi-aquatic predator, who also has a playful side, and it was here where I watched the otters who loved sliding down the banks to play in the water.

European otters (Lutra lutra) can live up to 10 years, and have a body length of around 60-80cm and tail length about 32-56cm, with the average weight of 8.2kg for a male and 6.0kg for females.  They have small ears, webbed feet and a streamlined body, and their diet is mainly fish and crustaceans, but they are opportunist feeders also eating birds, molluscs and frogs.  They build an underground holt into the banks of rivers and are often found near water, but do travel on land normally at night and can travel up to 20km in a day.  A female will have one litter a year between May and August of 2-5 cubs.  This was the late 1980s when many of our rivers were highly polluted, but are slowly recovering with stricter pollution control and laws to back them up.  At the time the Otter haven was very excited that they were secretly releasing some captive bred otters into the wild.

When I moved to Oxfordshire 13 years ago, I knew this should be the perfect otter habitat, and I volunteered to do some otter survey work once a month, first on the river Windrush and then at Culham Lock.  This entailed looking for footprints on muddy riverbanks (often confused with dog footprints), you have to look for the distinctive webbing and size, forefoot is about 60mm x 65mm, though juveniles and females have smaller feet.  The more distinctive clue is finding a deposit of faeces (spraints) with a characteristic musky odour.  This is deposited on prominent trees and logs on the river banks, to act as a calling card to mark territories ... and yes, I have collected otter poo!

Unfortunately I never got a positive recording around Culham, though I did get sightings of water voles and mink, though I did hear some rumours of sightings, often by people fishing, and fortunately these rumours are now becoming more factual.  Thirty years on, our rivers are much more cleaner, Otters are no longer persecuted and their numbers are on the increase.  There has been YouTube videos of otters at Radley lake.  When swimming on the surface, they have a distinctive V shaped wake, and when swimming under water, you have to follow the line of bubbles to see where they will break the surface.  Sadly a dead otter was spotted near Didcot in Autumn, killed on a road, one of the biggest causes of death.  However, roadkill is a good method of seeing how animals are dispersing around the country.

I recently contacted the TVERC (Thames Valley Environmental Records Centre) to ask about their most recent data.  They informed me they were definitely on the increase in Oxfordshire, with more sightings on the Thames and River Ock.  In the past I have had to travel to Skye and Devon to see wild otters, often on a dawn morning walk where otters were regularly seen.  It would be a dream come true if I saw a wild otter around Abingdon ... maybe you have been one of the lucky ones that this is a reality.

by Max (the Wildlife Watcher)