Grey seals

Grey seal, Ravenscar
Grey seal, Yorkshire

There are grey seals in Yorkshire, living in colonies on the coast, for example at Ravenscar. They tolerate humans, but not too close, and not if they feel their route to the sea is cut off. It is a wonderful privilege to be able to see and photograph them, but with that comes an obligation to be as discreet as possible, and to avoid disturbing them.

As well as Ravenscar in Yorkshire, there's a grey seal colony at Donna Nook, NE Lincolnshire.

Grey seals: classification

Grey seals, Ravenscar

Seals and walruses are within the Order Pinnipedia ('flap-footed'). Grey seals are in the family Phocidae (true seals), and the genus Halichoerus. The scientific name for the species is Halichoerus grypus, which is said to mean 'sea pig with a hooked nose'.

Grey seals are sometimes called Atlantic seals, because they live on both sides of the North Atlantic Ocean.

Grey seals: distribution

Britain's Mammals

About half the world's grey seals live in British and Irish waters (Britain's Mammals, by the People's Trust for Endangered Species). Eastern and western Atlantic populations have been genetically distinct for at least a million years, and could be considered as separate subspecies (Wikipedia).

Grey seals: description & behaviour

Grey seals play fighting
Grey seals play fighting

Grey seals are 1.4 to 2.5m long, with females averaging 1.8m, and males 2.1m. They weigh 130-144kg. Their eyes are large, and they have long whiskers.

A thick layer of blubber just beneath the skin insulates seals from the cold when they are in the water (Britain's Mammals).

Grey seals vs common seals

Grey seals have a longer face than common (harbour) seals, and fewer spots on their bodies.

Male and female grey seals

Grey seal bull
Grey seal bull

As well as the difference in size and weight noted above, there is considerable variation in grey seals' coloration. Bulls are darker, with just a few lighter patches. Cows' fur is lighter, with some dark patches. Seals' coats look lighter when they have been out of the water for some time, and darken when wet.

The differences in weight and colour between males and females are examples of their sexual dimorphism - different characteristics in the two sexes of the same species. Another distinction is the shape of their faces: bulls' noses have a more prominent bridge - called a Roman or aquiline nose; cows have a shorter nose without the prominent bridge. The photo below shows the difference.

Image showing the difference in shape of face between male and female grey seals
Female grey seal (above) and male

Lifespan is up to 20 years for males, and 35 years for females.

Grey seal: habitat and diet

Grey seals live on rocky coasts, and eat fish (especially sand eels), squid, lobster, and occasionally birds (Britain's Mammals). Their daily requirement is about 5kg of food (Wikipedia).

Grey seal: predators and threats

Grey seals, Ravenscar

Grey seals have no natural predators in UK waters, but are threatened by pollution and getting entangled in discarded fishing nets.

The UK population is about 200,000, and at the time of writing they are protected under the EC Habitats Directive.

Grey seals: life cycle

Mother seal and pup, Donna Nook

Between late September and December, a female seal gives birth to a single pup, which is born with creamy white fur, called lanugo.

Seal pup, Donna Nook
Seal pup, Donna Nook

The mother nurses the pup for 2-3 weeks, during which time it gains weight quickly from its mother's rich milk. The mother, on the other hand, loses weight, because she does not eat during this time.

After it is weaned, the pup is left to fend for itself. It stays on land and moults. Having shed its pup fur, the young seal grows dense, waterproof adult fur, and it can enter the water - usually at about one month old. It will then rely on instinct to catch fish.

When she finishes suckling her pup, a female is ready to mate again (

Grey seal courtship

Male grey seals seek to breed with several females. Some males defend a group of females, and others try to control access to beaches (Britain's Mammals). Like female seals, males don't eat during the mating period, and rely on their stored blubber for energy.

After mating, the gestation period is eleven and a half months, including a 3 month delay in the implantation of the fertilised egg (animalcorner). As a result, the female comes back to the same rocky or sandy place on the coast the following year to give birth and begin the cycle again.

Grey seals: video