The Gothenburg Seal Population Dynamics Group has been monitoring the harbour seals colony in Koster National Park every June since 2021 using drones to count individuals and assess their health. But what is everyday life like for a seal? We want to find out! Harbour seals can be very shy, meaning this can be a difficult task. Luckily, when the mum and pup pairs are not in swim school (where the mum teaches the pup to swim) they spend their time hauled out on rocks to rest and dry their fur. Thanks to funding from the Wild Animal Initiative, we have been able to deploy camera traps on the seal’s favorite rocks for the past two years. We set up the cameras in mid-May, before pupping has started, and collect them later in July.
A wild landscape: we have been using trail cameras to observe harbour seals during the pupping season without any human disturbance.
These cameras have allowed us to take secrete footage of the seals without any human disturbance. This has given us new insights into what life is like for seal mums and pups. We are particularly interested in exploring how the welfare of the mum effects the welfare of the pup.
A well earned rest: seals need time on land to rest and recover during busy foraging trips underwater. Pups in particular need these breaks as they don't yet have the strong swimming muscles of an older seal.
From the cameras we have seen what hard work it is to be a seal mum! Like human parent’s, seal mums get very little sleep and constantly have to look out for their baby - who likes to get into trouble, or keep mum awake by crawling on her face while she is trying to sleep.
Harbour seal pups also spend a lot of time drinking milk. The pups only stay with their mothers for the first month of life. During this month, the pup must gain a lot of weight for a chance of surviving the winter ahead. This means constantly drinking lots of fatty milk (a seal’s milk is between 40 and 50% fat content, compared to just under 4% in human milk). As the pup gains weight, the mother loses weight - over 20KG during nursing period! After this period with mum, the pups need to find their own food. When the pups first set out on their own, they aren’t very good at catching prey and rely on fat reserves until they can perfect the art of catching dinner. During the first five weeks post-weaning, pups lose about 21% of their mass.
The hard life of a seal mother: while harbour seal pups quickly gain weight in their first weeks of life, mothers lose a significant amount of weight. Modified from Hedd, Gales and Renouf (1995).
There is lots of drama in the daily life of a seal too! Seal mums are very protective over their babies. This means there can be lots of arguments and sometimes a fight between mums if one mum gets too close to another’s pup. In addition to arguments between themselves, seals face challenges from the environment. In bad weather conditions, pups can be washed off rocks and be too weak to climb back up. This can also be a problem if the seals are disturbed by people and the pup gets knocked of the rock. Mum then needs to find the pup before the pup becomes lost and help them to the safety of a rock. This is why responsible seal watching practices are so important. Never directly approach seals on land and keep an eye out for signs of disturbance.
Caught on camera: harbour seal mothers are always on the lookout for any threats to their pups.
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