The veil has been lifted ever so slightly on the world of one of the River Thames’ most mysterious inhabitants, following the discovery of a wild otter on The Highway in Wapping recently. On Friday 22nd September 2006 a young otter was found dead by a local resident. A post mortem a few days later confirmed this is the first wild otter to be found in Central London in 100 years.
Environment Agency experts believe the notoriously shy mammal had travelled to London down the River Lea, most likely having left the river at Shadwell Steps around 500m from where the otter, after being hit by a car, was found. The discovery of this young male, measuring 122cm and weighing 9.7kg, within a mile of Tower Bridge, signals the welcome return of one of Britain’s most loved mammals to the capital. Although otter numbers in the rivers surrounding London are still low compared to the rest of the country this is clear evidence that the population is breeding and spreading. The return of the otter to London is as significant as the earlier return of the salmon to the River Thames.
The work of the Environment Agency, local wildlife trusts and water companies to improve water quality, riverbank habitats and wetlands has undoubtedly helped the otter populations to establish and grow. Local environmental organization the Lea Rivers Trust has also been doing great work in helping the otters by creating habitats, both ‘holts’ – underground breeding chambers, and ‘couches’, the technical term for secluded habitats for otters to hold up in during the day, away from people. Part of their work also includes building otter ladders to help them climb over steep locks and river banks and avoid detours involving crossing busy roads. The Trust has also planted several thousand trees over the past year specifically to create sites where otters can hide and breed.
Sadly the Lea Rivers Trust has since ceased operation, after 15 years shaping the environment of the Lea Valley, due to the changing agendas in the Lea Valley, funding and other pressures. Mark Gallant, their Project Officer who has played an active part in Tower Habitats for several years, will be sadly missed. We wish him well in his new post at the North West Kent Countryside Project.
Otters are members of the Mustelid family which includes badgers, polecats, martens, weasels, stoats and mink.
There are 13 known species of otter in the world but the only one found in the UK is the European (or Eurasian) otter (Lutra lutra).
Length: Average 1.2m (dogs), 1m (females)
Weight: Average 10.3kg (dogs), 7.4kg (females)
Colour: Medium to dark brown above and lighter underneath.
Diet: Mainly fish, but also birds, small mammals, amphibians, crustaceans and molluscs.
Breeding: Only once every 2 years as the cubs remain dependent on their mother for a year.
Offspring: 1-4 cubs
Lifespan: Average 4 years due to so many threats, although they can live 8-12 years.
Habitat: Mainly rivers, but also canals, marshes, small streams, ditches, ponds and lakes. They also inhabit estuaries and coastal areas.
Home range: Depends on food supply but can be from 1 km along a rich coast to 40km along some rivers.
Resting sites: Called holts, often tree roots but also drains, caves and holes in rockfalls. They will also rest above ground in vegetation, sometimes called couches.
Social structure: As otters are very territorial they tend to live alone, except during mating and for a period, dependent on the mother, after the cubs are born.
Physical features: Short legs, webbed feet and claws, long stream-lined body, small ears and a broad muzzle, sensitive whiskers around snout to help detect prey, 2 layers of fur – a thick waterproof outer one and a warm inner one.
Special abilities: The European otter has an acute sense of sight, smell and hearing. The eyes are placed high on the head so that it can see when the rest of the body is below water.
Did you know…?
Otters can swim at speeds of 12km/h underwater and can travel for up to 400m before surfacing for air. When it dives, an otter closes its nostrils and ears. Otters are the only truly semi-aquatic members of the Mustelid family.
Photo by Catherine Twigg