Birth room in Wadden Sea: grey seals born!

The uninhabited islands of Griend and Richel in the Dutch Wadden Sea are equally inhabited. The birth season of the grey seal is in full swing. On the higher sandplates in the Wadden region, the seal puppies see the light of day this winter.

Big eyes, a woolly white coat and a birth weight between 10 and 20 kilos. They look cute, but make no mistake, says Erik Jansen, ecologist of Natuurmonumenten at Schiermonnikoog. In no time the grey seals grow into huge animals.

When they drink milk to their mother, the pups gain about two kilos a day. โ€œThe males can grow up to three meters long and weigh more than 300 kilosโ€, explains Jansen.

Not so strange when you consider that an adult gray seal eats an average of 5.7 kilos of fish a day. Jansen: โ€œThe grey seal with its powerful jaws and sharp teeth is therefore one of the top predators of the Wadden Sea.โ€

Before the time comes, the youngsters depend on their mother who casts her young just after spring tide, the period when the difference between high and low water is greatest.

She does so in a carefully chosen place, says ecologist Jansen. โ€œOn the highest part of a mudflats. A puppy cant swim right away, so its important that it is born in a place that cant walk underwater.โ€

Quiet

In addition, a quiet place is chosen where no people come, because (young) gray seals are very sensitive to disturbance. โ€œThats why theyre not born on Vlieland, for example,โ€ says Jansen.

Does the regular seal get her boy in the summer, the gray sheds her baby in winter. According to Jansen, it seems that they come into the world earlier and earlier in the winter. โ€œPreviously, most of them came around Christmas, nowadays the first puppies are born at the end of November.โ€

According to the ecologist, how exactly this is done is not entirely clear. Climate change could be a cause. Also, the influx of British seals that have different casting times and a large proportion of older seals that get a young earlier in the winter are obvious explanations.

A female gets one cub at a time after she has worn it for a total of 11.5 months. But since the embryo develops only after three months, the actual gestation period is somewhat shorter.

Every five hours, the newborn puppy is suckled. โ€œAfter about three weeks, the young are left to their fate. Many puppies do not survive without their mother, but fortunately it usually goes well. They can eat on their fat reserves for about a week before they start looking for food themselves.โ€

Within a month after the birth of the seals, the males come ashore. They clap their fins to attract the attention of the females and to scare each other off.

Then they fight each other to determine which one is allowed to mate with all females. โ€œThats not exactly soft,โ€ says Jansen. โ€œAfter the battle, the king remains and the other males drip off. The females are fertilized again.โ€

According

to Jansen, the mammals are very mobile. โ€œThey swim all the way to England with ease to go fishing there. The regular seal usually stays a little close to the Wadden Sea.โ€

It goes well with the grey seals in the Netherlands. The number in the Wadden Sea is rising. Last spring the University of Wageningen counted 5687, twenty percent more than the year before. There were 7649 in the international Wadden Sea; 17 percent more.

Were still investigating whether this is due to the coronacrisis. It is quite possible that the gray seal had little human disturbance due to lockdowns.

Large habitat

Grey seals live not only in our Wadden Sea, but also along the coasts of the North Atlantic Ocean. The adult animals can be spotted in the Baltic Sea, near Iceland, the Faroe Islands, Norway to Great Britain and near northeast Canada. Almost all grey seals (95%) in Europe live in the North Sea around the Scottish islands and along the British coast.

Fifty years

The males of the gray seal can reach up to three meters and weigh 350 kilograms. Females grow up to two meters and weigh 200 kilos. The seals are born with a white coat, but later turn gray with black spots. The females are usually lighter in color. They eat a lot of fish and shellfish and sometimes a bird. The gray seal can reach up to 50 years.