15/03/2006 - The Environment
Agency has built a special ‘otter pass’
into the A5 culvert during construction
of the flood risk management scheme at Cannock
to encourage otters to return to the Ridings
Brook. The otter pass, comprising a 450mm
diameter tube laid under the A5, will allow
otters to move along the river safely and
encourage them to spread to new areas such
as Cannock.
Although we have found no evidence of otters
along Ridings Brook, we know that they are
close by. We found evidence of otters around
Saredon Brook and the Hatherton Branch Canal
during survey work in 2001 and we believe
that the River Penk and its tributaries
help otters cross from the upper reaches
of the River Severn into the River Trent.
Otters can be deterred from passing through
culverts, especially when river flows are
high and, if they try to pass over the top
of the culvert, they are at risk of death
or injury on the road. Deaths from road
kills remain a serious problem. At least
400 otters are killed on Britain’s roads
each year.
The presence of otters is a good indicator
of the health of our rivers. Water quality
has improved greatly since otter populations
reached their low point in the 1950s, helped
by investment in technology by sewerage
companies and the outlawing of organochlorine
pesticides. They are now protected under
the Wildlife & Countryside Act and the
Habitat Regulations.
Cannock Project Manager, Roger Prestwood,
says: "When we carry out work to protect
people from flooding, we try to find opportunities
to protect our natural heritage as well.
Otters are an important part of this heritage.
Their populations are slowly recovering
after coming close to extinction in the
1950s, but they are still vulnerable. We
are doing our bit to encourage them at Cannock
by making it possible for them to travel
safely along the river. We hope that this
will tempt otters to return to the Ridings
Brook."
More Information
During the 1950’s the otter population
suffered a catastrophic decline, mainly
due to two chemicals used in agriculture,
Dieldrin and Aldrin. This decline continued
throughout the 1960’s and 70’s, and by this
time otters were effectively extinct in
the Midlands.
Because otters avoid disturbance and are
largely nocturnal, survey and monitoring
usually has to be carried out by searching
for footprints and droppings (known as spraints).
By the fourth Otter Survey (2000 – 2002)
otter signs were found in the 24% of sites
in the Trent catchment and 39% in the Severn
catchment. The national average is 34-35%
so the Midlands Region is about average.
The Trent catchment is one of the big success
stories in England. In the last ten years,
otters have spread from the Tern (Severn
catchment), via streams and brooks into
the Sow and Penk (Trent catchment) and colonised
most of the catchment. The Trent has shown
one of the biggest otter increases of any
region - a lot better than expected, in
fact. This is largely because otters have
re-colonised the Trent more quickly than
could have been foreseen.
The otter has been given full legal protection
throughout England and Wales from 1978,
in Scotland from 1982 and in Northern Ireland
from 1985. It is an offence under the Wildlife
and Countryside Act 1981 (Sections 9.1 and
9.4, Schedule 5) to kill, injure or take
an otter from the wild without a licence;
to damage or obstruct a holt; or disturb
an otter in its resting place. Licences
are required for checking holts or for carrying
out work that may disturb otters, such as
the management of trees that are known to
be used as resting sites.
The otter is listed in the Bern Convention
and the Convention on International Trade
of Endangered Species (CITES). It requires
special protection measures under the European
Habitats Directive (92/43/EEC). Its listing
in Annex 2 requires the designation of Special
Areas of Conservation (SACs) for sites supporting
important otter populations.
Facts and figures
Length: Average 1.2m (dogs), 1m (bitches)
Weight: Average 10.3kg (dogs), 7.4kg (bitches)
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.
Gestation: 9 weeks
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.
