Have you ever seen a gannet?

These birds are truly remarkable; with superpowers the likes of which we can only dream of! They’re rowdy, grumpy, loving, intelligent and greedy. Hopefully, in this blog, I’m able to offer a little bit more context and information about one of my all time favourite birds…

The gannets’ Latin name is Morus bassanus – a name which derivates from the world’s largest population of gannets on Bass Rock in North Berwick. During the summer over 150,000 gannets breed on this small rock which is only a few hundred metres across. I was hugely fortunate to go to Bass Rock with a very talented photographer Brian Matthews back in 2019. We chartered a small fishing boat and captured these amazing animals at sunrise. (But that’s a story for another day!)

Gannet Biology

Gannets are an amber listed species in the UK. They weigh between 2-4kg with a wingspan of about 160-180cm. This makes them pretty impressive on their own but when they’re en masse, it’s borderline scary! Their size has gained the accolade of being the largest seabird of the Palearctic. Interestingly, there is very little physiological difference between males and females – they are not sexually dimorphic and look almost identical in size and shape. However, it is possible to notice some difference in breeding season when the males’ colours become more prominent.

Gannet hovering before landing

Without a doubt the most impressive behaviour of the gannets is their diving. They will circle in the air, honing in on their prey before plummeting into the water and ferocious speeds of 55-65mph – even on calm days. In order to cope with the pressure of impact, they have developed cushioning throughout their body but in particular around their eyes and brain; nictitating membranes protect the eyes (like a pair of goggles) which zip into action just before impact. They have air sacs throughout their bodies, below the sternum, between the ribs and around the pectoral muscles. These air sacs can be inflated and deflated as the bird breaths in in preparation to dive.

Unlike the cormorants and shags, these impressive birds have an oil gland making them waterproof as well as a fatty layer to keep them warm in the cold waters of the Atlantic.

All these adaptations make them perfectly suited for aerial attacks on fish. The forward facing eyes and ability to almost hover, mean that they can overcome the “parallax” effect of water (where objects aren’t exactly where they appear to be) and be highly accurate with their hunts.

They actually have considerably smaller wing muscles than other birds. In most birds, flight muscles make up around 20% of the body whereas in gannets this is only about 13%. As a result, these birds struggle to get airborne from flat surfaces or from the ocean. In the infamous words of Chicken Run they need “THRUST!” As a result, one can see gannets throwing themselves off the cliffs in order to get going. Also because of their weight and weaker flight muscles, they often get saturated and exhausted if they land on the sea or get too waterlogged. This is why their bodies are often found along beach lines.

Circadian Rhythms

Gannets are monogamous. Every year between March-May, they return from their overwintering locations along the Western coast of Africa to the same breeding site with the same mate and raise just one egg. The oldest birds will return first and the younger will arrive a few weeks later. These ones are not usually of breeding age and will stay out to the edges of the colony. They may even build nests but won’t breed until they’re 4-5 years old.

Gannets will meet their old partner at their old nest site, greeting each other with beak tapping and harsh calls. It’s such a beautiful site to see these lovebirds see each other again after a winter apart! Gannets are not super intelligent and sometimes females will lay in the wrong nest site, in which case a female may inadvertently raise two chicks through sheer ignorance!

The gannet chicks are bald initially, then they grow a downy fluff before turning black and speckled. They’ll fledge at this later stage (usually at around 13 weeks). At this point the adults will head off back to Africa. It’s not known if birds from the same breeding location also head to the same overwintering location but the area of disbursal is about 800-1600km – which is pretty staggering for such a large bird!

The birds will live and feed along this African coastline until instinct calls them back to their initial breeding site next year.

A recently fledged gannet showing its juvenile colourations

Troup Head

RSPB Troup Head is a hidden gem of Aberdeenshire. Up a nondescript single track road, past a little farm and from a tiny car park, you can see around 6,500 breeding pairs of gannets. It was established in 1988 and is now the second largest in Scotland (the largest being Bass Rock). The reserve shows stunning views of the birds from pretty exposed viewpoints. It’s not for the squeamish and there are always moments when I go and think “blimy, that’s a long way down!” But it’s genuinely one of my favourite spots, it’s rarely busy and alongside the gannets are a good sized colonies of fulmars too as well as a multitude of other wildlife along the coast. If you’d like to book a photography session with me along this coastline just email me at williamroberthall@hotmail.co.uk

Leave a Reply

%d bloggers like this: