European
otters are currently thought to be doing OK in Portugal, and in a survey of
central Portugal during August 1980, evidence of otters was found in 70 percent
of the 90 stations visited, in major rivers and their tributaries, in small
streams connecting pools and at fetid pools in semi-dry riverbeds.
They are
often overlooked as a species in the Algarve due to their shy nature and mainly
nocturnal habits. The Eurasian otter (Lutra lutra) is the only species found in
Europe and its population has become very depleted, even becoming extinct in
some western countries.
The
Eurasian otter is also known as the European otter, common otter, or Old World
otter, and is a semiaquatic mammal, listed as Near Threatened under the
Endangered Species Act and is also listed under the Marine Mammal Protection
Act.
Spraint
(droppings) is the best evidence to prove their presence, which they leave at
strategic and prominent places - such as raised rocks - which mark their
territory and feeding points. Fish bones and crayfish shells may be visible in
the spraint as further evidence of their inhabitance.
The
European otter is a medium-sized carnivore in the Mustelidae, or weasel family,
along with the pine marten, badger and stoat. River otters are up to 90 cm in
body length, with a long tail measuring 35-45cms.
River
otters and sea otters are similar, but while both types love to swim, the
swimming behaviours they engage in are quite distinct – a river otter lounges
around riverbanks and swims with its belly down, keeping the majority of its
body below the water, whereas sea otters are found only in salt water and
rarely go on land, often floating on their backs even while they’re eating, and
have been known to hold hands with others during sleep to prevent drifting apart.
Their
swimming mechanisms are different too - river otters have four short webbed,
clawed feet, which enable them to swim at speeds up to 12km underwater, while
sea otters use their two webbed hind feet and tail to propel them through the
water. River otters can dive to a depth of around 18m, whereas sea otters can
dive an average of 61m. How long can a European otter hold its breath? An
average of 4 minutes - sea otters surprisingly a mere 5 minutes considering how
much deeper they go, and both can close their ears and nostrils whilst
underwater.
Otters
are often included amongst the ten most intelligent creatures on the planet and
belong to a select few animals that use tools, in league with apes, monkeys,
and beavers. Not only are they highly intelligent, but they seem aware of their
intelligence, too. River otters make six sounds, characterised as chirps,
squeaks, chuckles, hahs, growls, and screams, while sea otters have nine
vocalisations - distress screams and contented coos, whines, whistles, growls,
and snarls – all of which are used in different social interactions.
European
otter fur is short and dense, with some 57,800 hairs/cm2, which traps air for
the sole purpose of insulating the body. They also have extra sensitive
whiskers that they use to detect the movement of their prey in the water, even
if it is dark and murky.
Female
otters are smaller than males and do not mate for life, with females rearing up
to 4 young at a time, keeping them safe by their sides and in dens they build
on riverbanks, known as 'holts'. New-born pups need constant attention and will
stay with their mother for six months until they develop survival skills.
Excellent and lithe swimmers, the young are in the water by 10 weeks of age,
with fur so dense that they can't dive underwater until they get adult fur!
They
require clean rivers, with an abundant source of food, and vegetation in which
to hide. Although aquatic creatures are their most common prey, they will eat
almost anything they can catch and overpower, but an otter’s exact diet
depends on its species and habitat – and amusingly wash themselves after every
meal.
Are they
afraid of anything? Yes, apparently dogs, especially large ones, and will view
them as predators.
Marilyn writes regularly for The Portugal News, and has lived in the Algarve for some years. A dog-lover, she has lived in Ireland, UK, Bermuda and the Isle of Man.