Can you tell the most common seagulls apart?

A seagull is not just a seagull.

Some members of the gull family Laridae can be difficult to tell apart.

Here are some tips from Professor Thor Harald Ringsby at NTNU’s Department of Biology at the Gjærevoll Centre, and researcher Ivar Herfindal at the Gjærevoll Centre.

Both are experienced biologists who are well-versed in species identification as well as how changes in the environment, climate, and land use affect different species.

Start with one species

The six most common gull species in Norway are the herring gull, common gull, great black-backed gull, lesser black-backed gull, black-legged kittiwake, and black-headed gull.

"They are adapted to different environments and can be identified by size, the colour of the back, wings, and head, as well as the colour of the beak and legs,” says Thor Harald Ringsby.

Norway is also home to glaucous gulls, although they are rare in the south because they breed in Svalbard, Bjørnøya, and Jan Mayen, the researcher explains.

“Start by looking for the most obvious characteristics, such as the colour on the back, or the colour of the legs. That’s how you train your eye for what to look for,” he says.

Pink feet? Yellow? Take it step by step

If the gull has a black back, it is either a great black-backed gull or a lesser black-backed gull.

The next step is to check the colour of its feet. Pink feet means it’s a great black-backed gull. Yellow feet means it’s a lesser black-backed gull.

But if the feet are pink, the back is grey, and the wingtips are black and white, it’s a herring gull.

The somewhat smaller common gull has the same markings, but its feet are a yellowish-green.

Build a knowledge base, researcher advises

“If you’re familiar with a few species, it’s easier to see how an unknown species differs from the ones you know. Then you can check in a bird book or on the internet. If you’ve learned the important distinguishing characteristics, it will be easier to compare with gull species you haven’t learned yet,” says Ringsby.

The four large gull species all have a red spot on the lower beak, which the smaller ones lack. Size is also important:

“If you’re in the city centre with seagulls in the square and a much larger gull suddenly appears and has a black back and pink legs, you can conclude that it’s a great black-backed gull. If the back is grey, and the legs are pink, it’s most likely a herring gull," he says.

This is how you build your own knowledge base of species you recognise.

That also makes it easier to add new ones, according to the professor.

Only one has short, black feet

Black-legged kittiwakes are becoming more and more common in Norway’s coastal towns, from Møre and northwards.

From a distance, kittiwakes are quite similar to the common gull, but have short and completely black feet. Their wingtips are also black, without any white. 

But black-headed gulls are perhaps the easiest of all to recognise.

“It has a brownish-black head, hence the name, so it's easy to recognise. At least in its adult summer plumage,” says Ivar Herfindal.

Help from apps and health benefits

Both researchers recommend the gull guide from the Norwegian Institute for Nature Research (NINA) (link in Norwegian). The Merlin app is used by professionals and amateurs alike and is good at identifying birdsong.

“Open the app, put it on listen, and then the picture of the bird singing comes up. If there are 10-12 species singing at the same time, the app marks which of them is singing at any given time," says Ringsby.

It’s a very useful tool that can also distinguish between different seagulls. But the researcher says that the results should be taken with a pinch of salt. It’s not infallible.

He also believes that developing an interest in birds is good for your health.

“Birdsong has a calming effect on our mental health and can be good medicine in an otherwise hectic everyday life,” he says.

Seagull noise – or the sound of spring

Common gulls were once abundant on the Norwegian coast. Now they are almost gone from some areas, while city populations have grown.

These gulls nest on rooftops, and walk the streets in constant search for food.

Some residents believe that there are too many. They can steal your food, or attack from the air to protect chicks that have jumped out of the nest before they can fly.

And they can be very loud during the breeding season.

“For others, the sound of seagulls is also the sound of spring, and a sign that nature continues to take its course, despite all human interference,” says Herfindal.

Spring in the fields, Africa in winter

The large flocks of birds you may have seen in newly ploughed fields in the spring are often lesser black-backed gulls.

In winter, the seagull population thins. The lesser black-backed gull migrates the farthest, with some travelling all the way to Africa.

Kittiwakes spend the winter on the open sea over large parts of the North Atlantic and rarely come ashore.

The gulls you see in cities during winter are often herring gulls.

Some herring gulls and great black-backed gulls remain along the coast.

Common gulls and black-headed gulls migrate south to the North Sea areas around Denmark, the Netherlands, and the United Kingdom.

Seagulls take a few years before they develop their adult plumage. This can make it a little difficult to tell them apart, even for seasoned bird watchers.

4 out of 8 gulls are endangered

4 of these 8 gulls are on the Red List: the herring gull, black-legged kittiwake, black-headed gull, and common gull.

Gull species have been in decline for many decades because there’s less food in the ocean. In recent years, several outbreaks of bird flu have affected the kittiwake population in particular.

Several species have lived alongside humans on the coast for thousands of years, and have benefited from thing such as fish scraps.

“One of the reasons for the decline is probably less access to food, as fisheries became more industrialised and production moved from the coast and on board large production vessels. There's also generally less food in the sea,” says Herfindal.

The American mink, which is an alien species in Norway, has also made nesting sites along the Norwegian coast dangerous, the researcher points out.

But is it really such a problem if a species relocates and adapts to urban life, as long as it survives?

Stress vs. security

Herfindal, who studies applied ecology, does not believe gulls particularly enjoy being close to people.

“Living in the city is stressful for them and can set them up for lots of disturbances, but cities also give them the most important thing: Food and safe nesting sites,” he says.

The Gjærevoll Centre will lead one of four new centres for sustainable land and nature use.

At the Centre of Biodiversity Forecasting, Herfindal and his colleagues will work on scenarios for how the way we use and manage land affects species and diversity.

“Species will react differently to changes in available land. If we then add, for example, climate change and pollution on top of that, the effects quickly become very negative for the vast majority of our species,” says Herfindal.

Birds also have the right to live in the city

Thor Harald Ringsby believes it is important to be willing to share. People should think of the city as just as much a habitat and home for the birds and animals that choose to live here, as it is for us humans.

We must find ways to promote rich biodiversity in parks, green areas, and in the city in general, he argues.

“Throughout history, we have exploited nature only for our own good. In the future, it's important that we shift our values by acknowledging that we are part of the same ecosystem and facilitate good ways of living together,” he says.

House sparrows also provide knowledge about gulls

Ringsby has been involved in NTNU’s house sparrow project since its inception in 1993. The researchers are studying a total of 18 populations of house sparrows on islands along the Helgeland coast.

They investigate fluctuations in populations over time by looking at what affects fertility and dispersal patterns, as well as changes in genetic variation and evolutionary processes.

The house sparrow population in Helgeland is naturally split up between different islands.

What happens to this population has a lot in common with what happens to endangered species when undeveloped natural areas are bisected by roads or other infrastructure, or agriculture, forestry, and urbanisation.

Nature loses out when areas that were previously connected become like islands in the landscape.

“Much of what's happening with the decline in gull populations can be understood through the knowledge we have gained through the house sparrow project,” says Ringsby.

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