HARBOUR OR GREY SEAL?
When walking along the Irish coastline, you can regularly spot 2 species of seal: the grey seal and the harbour (or common) seal. Sometimes, you can even spot these both in the same area. But how do you know which one you see? It is actually surprisingly easy to tell the two apart from one another.
Harbour seal
© Kristina Steinmetz
Grey seal
Size
The most obvious difference is that grey seals are much larger than harbour seals. The adult harbour seal can be as long as 1.8m. Grey seals on the other hand regularly get to a length of 2.1m and bulls get grow even larger (up to 3.3m). But what if there is only one species present? Especially when watching from a distance, judging size is not an easy task! Luckily there is a lot more identifying features that can help you.
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The head
Harbour seals have V-shaped nostrils that meet towards the bottom, which can be seen well in the pictures on the left. In contrast, grey seals have parallel nostrils (i.e. they do not meet at the bottom). Grey seals have a much flatter nose than harbor seals which is called a ‘Roman nose’ (this is particularly visible in the picture of a male adult, lower left) and their head seems elongated in comparison. Harbour seals have a more concave head and a pronounced forehead. For grey seals, the eyes are located midway between the nose and the back of the head whereas they are more on the front of the head for harbor seals. Contrasting to harbour seals, grey seals actually have a double chin.
In profile, the pronounced forehead of the harbour seal (left) and the 'Roman nose' of the grey seal (right) show how easily the species can be identified.
General appearance
Besides the helpful differences just looking at the individual’s head, there are also differences in the general appearance. Harbour seals have quite a uniformly spotted pattern consisting of numerous small dots. Grey seals have a more obvious pattern and their spots are a lot more irregularly shaped (no dots). A general warning, a seal’s pelage pattern can appear very different depending on whether an animal is currently undergoing the annual moult and also whether the fur is wet or dry. Overall, the features of the harbour seal make it look very cute to the general eye. Grey seals appear more bulky and while they are gorgeous animals, next to a harbour seal, they will not appear cute.
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Pupping
Pupping season for grey seals is from September to December, whereas harbour seals are pupping during June and July. Grey seal pups still have their white lanugo coat, which makes them fairly easy to spot. Harbour seal pups lose their lanugo before birth and are born with their patterned adult coat. Both species are lactating for about 4 weeks, after which time the pups are on their own. Another difference is that harbour seal pups go into the water right away learning how to swim whereas grey seal pups stay on land until their lanugo coat is moulted and they are weaned.
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The annual moult
Both species are mating after their respective pupping season and will moult their fur following this. Harbour seals moult between August and September whereas grey seals moult from February to April.
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Haul-out behavior
When a group of seals is hauling out, grey seals generally lie much closer together. Harbour seals like their own space and will make aggressive noises to keep this. While they do make sounds to keep their personal space, harbor seals are quiet and vocalisations are not very noisy. They appear almost silent in comparison to grey seals. If you do hear a haunted howl there, chances are you have a grey seal in the group. Harbour seals also tend to do their famous 'banana pose' when hauling out. This is a position where they have both their head and tail up in the air.
QUIZ TIME! DO YOU KNOW THE SEAL SPECIES?
Now that you know all about the difference between harbour seals and grey seals, why not test this newfound knowledge? Here are a few photographs of seals around the Irish coastline. Do you know which one is which? To see the answer and find out if you were right, simply move your cursor over the picture.
Harbour seal
Grey seal (female)
Grey seal
Grey seal
Harbour seals
Harbour seal
Grey seals
(look how close together they are)
Grey seal
Harbour seal
Harbour seal