The grey seal is known as the Atlantic grey
seal or the horsehead seal.
Male seals are called bulls and females are
referred to as cows.
Grey seals can dive between 30 and 70 metres
below the surface and submerge for between
5 and 10 minutes. They haul out onto the beach
or onto rocks between tides and they often
bask in the sun. It’s believed that this
helps to remove parasites from their skin.
Grey seals waving their flippers in apparent
greeting are actually cooling down. The flippers
have a large blood supply to allow heat to
escape.
The grey seals' breeding area is known as
a rookery.
Rookeries are formed on various types of habitat
including sandy beaches like the one here
at Horsey.
Sometimes cows come up onto the dunes to give
birth.
In other places rocky islands, caves or ice
may be used as rookeries.
Pupping season at the Horsey Beach seal colony
occurs in the winter. Pups are born between
late October and early February.
Pregnant cows arrive on the beach first and
usually give birth to their pup a day after
coming ashore.
The mother will sniff the new pup during the
first 30 minutes after its birth in order
to form an association between her pup and
its smell.
Newborn pups weigh about 15 kilos. They have
poor coordination and their fur is not waterproof.
They are also lacking in blubber, which is
a thick layer of fat. Once the blubber develops
it helps to keep the seals warm.
Pups start to suckle within six hours of being
born.
They suckle from their mother for 18 to 21
days. Ideally, pups will suckle 6 times a
day for about 10 minutes at a time.
They gain about 2 kilos of weight each day
due to the high fat content of the mother's
milk.
By the time a pup is weaned it can weigh 45
kilos.
Once the pup has been weaned the mother leaves
it to fend for itself.
It stays on the beach for three weeks until
it has moulted, losing the dense, soft silky
white fur it was born with.
When they finally enter the sea, pups have
to learn what they can eat and how to catch
it.
Unfortunately, many do not make it. Starvation
and disease take their toll and only 40% of
the pups survive their first year.
16% of cows are sexually mature on their third
birthday and give birth to their first young
one year later, following an 11 month gestation
period.
This figure rises to 71% by the fourth year
and 89% by the fifth year of life.
The males also become sexually mature at age
three, but due to competition for females, rarely
mate before they are eight years old.
During the months prior to the breeding season,
both bulls and cows actively feed and their
diet includes a variety of species of fish
and shellfish.
Studies from Scotland, The Netherlands and
Germany show that grey seals will also prey
and feed on large animals like harbour seals
and harbour porpoises.
Cows feed in order to build up fat reserves.
This extra fat helps to sustain the mother
and her calf during the fasting period which
follows the birth, usually lasting for three
weeks.
Cows are smaller than bulls, reaching up to
2 metres long and weighing up to 150 kilos.
They can live for up to 35 years and attain
full size by about 15 years of age.
Cows also tend to be paler in colour than
bulls: they are silver-grey with small scattered
dark spots, while bulls have a dark grey background
colour with silver-grey spots.
In both bulls and cows the belly is lighter
than the back.
The nose of a grey seal can distinguish a
bull from a cow. The bull has a long, arched
nose which is the basis for its Latin name,
Halichoerus grypus, which means the hooked-nosed
sea pig. Cows have a narrower, shorter nose.
Cows also have a less rounded profile than
bulls.
Bulls also actively feed during the months
prior to the breeding season and, like the
females, they also fast during the breeding
season. A male’s fast may last for up to
six weeks.
Bulls can grow to over 3 metres long. Bulls
can weigh up to 300 kilos and the average
adult male reaches his maximum size at 11
years of age.
Bulls usually enter the rookeries once the
females have given birth and they try to gain
sole access to groups of females.
Territorial fighting occurs during the breeding
season. Successful bulls may mate with up
to 10 cows.
The shoulders of the bull are massive with
the overall bulk supplemented by a buildup
of scar tissue from fighting during breeding
seasons.
Grey seals are attentive mothers and defend
their pups against predation and intrusion
but a mother may abandon her pup if she is
disturbed by people.
Also, seals are wild animals and can be aggressive.
They can inflict serious bites and carry bacteria
in their mouths which can cause deep infections.
Under no circumstances should you approach
a basking seal.
At Horsey Beach, seal wardens create temporary
barriers to encourage visitors to keep a safe
distance.
With a little care and a good zoom lens or
binoculars everyone can enjoy observing these
marine mammals in their natural environment.
