A downpour of cub birds

20 July, 2021
A researcher catches a guillemot cub that has just crash-landed on the pebble beach. Photo: Leif Eiranson

A steel ramp, a breathtaking precipice and at the bottom of the sea. The waves beat against the rock wall. And there we go. In order to be able to get down to the beach where the research project is being carried out, a ramp and a fire ladder have been drilled into the limestone.

“Good thing you’re not afraid of heights,” I say loudly as I climb down the 12-metre ladder. I don’t know why I say that. Maybe it’s to calm myself while convulsively holding the steel bars and fighting against the back weight of my backpack.

Someone who quickly climbs down the ladder without problems is Jonas Hentati Sundberg, marine biologist and research leader at Stora Karlsö. He has been here every summer for over 20 years.

“You’ll probably get your feet wet, but I actually think it’s easier for you to go through the water than to try to climb the mountain with all the equipment.

When we get down the ladder, it’s time for the next stage, to wade into the water along the cliff edge. Although my hiking boots usually have a good grip on the surface, even they are helpless against seagrass-covered rocks. On my shoulder wobbles a tripod, and on my back my backpack. Even though it’s after 9 p.m., it’s still warm in the air – and in the ocean. Three days after returning home, I will still need to wear my sour boots to dry.

It strikes me that it is rare for outsiders to take part in how physically demanding researchers’ fieldwork can be. Many times they have to get through terrain that is difficult to access – the wild nature rarely has trodden paths – and their equipment can weigh tens of kilograms. Research is much more than white coats, labs, and excel reports.

bird ringing
A wooden table and two benches will be used as a research station when the guillemot are to be ringed. Photo: Leif Eiranson

After ten minutes of hiking through water and over cliffs, we finally reach our final destination: A small pebble beach, where there is a table with associated benches waiting. It is the research station.

Above our heads, the mountain spreads out. Among the rock shelves, the guillemot are crowded in a row. Parents fly in and out of their nests. They control what is happening on the beach and what new creatures have besieged there.

Not a cloud is visible, but soon the sky will open up. Not by rain – but by a downpour of down balls.

– When it starts, it rains like… What are they saying in the Bible? I can’t figure out what they say… but at least hundreds of guillemot will fall here soon, says Jonas, pointing to the pebble beach.

Small metal rings with serial numbers are laid out on the table, next to notepads and what looks to be tweezers. Jonas’ hands work methodically, accustomedly. He turns his gaze up to the rock shelves.

“The chicks leave the nest when they are around 20 days old. The parents can’t bear to feed them any more then, and it’s also time for them to learn how to dive and find fish on their own.

The researchers are waiting for a cub to jump down from the over 30-meter-high rock shelf. Photo: Leif Eiranson

He points out at the guillemots bobbing out in the sea.

“For two weeks each summer, the birds jump under cover of darkness. Directly down here from the cliff. The fathers wait for the chicks out in the water while the mother props on the cub to jump. After the cub has jumped, they meet their father in the sea, and then swim away and spend two to three months on the water, to learn to dive and hunt for fish on their own. They won’t be back here until next year again.

Jumping out of your nest sounds like something natural to a bird – it’s the textbook example of how a bird learns to fly. The problem is that the guillemot chicks cannot fly when they leave their nest. Their jump, therefore, ends with a crash landing on the stones. For a few seconds they lie unconscious on the beach. But after a few seconds, they begin to move, shaking off the fall and running out to sea.

“Around 99 per cent of all baby birds survive the jump off the shelf. They have a lot of fat on their stomachs, and a soft skeleton that resembles the cartilage in our ears, which makes the landing quite soft. Once they have landed on the ground, we try to catch them and ring them.

A little guillemot cub takes a break before continuing its journey out to sea. Photo: Leif Eiranson

The guillemots are sometimes called Sweden’s penguins. But unlike penguins, these birds can actually fly — albeit a little clumsily. However, this flight precocious has not evolved at the time of the jump, which may seem like an evolutionary defect. But it is apparently common among birds. Even turtles and seagulls allow their young to leave the nest before they are ready to fly.

“There are actually guillemots in other parts of the world that jump from a height of several 100 metres. The guillemots do not need to be able to fly when jumping. First, they will learn to dive,” says Jonas.

The sound on the beach is deafening. Using the word cacophony feels enticing, but on reflection, symphony feels like the right choice of words. On Stora Karlsö, the birds live in symbiosis with each other.

“There are several birds that thrive on Stora Karlsö. We have one of Europe’s densest populations of house martins, but even the thunderstorm thrives here and the otherwise endangered eider seems to thrive,” says Jonas.

Jonas Hentati
Jonas Hentati has been on Stora Karlsö for 20 years. He has ringed thousands of guillemots, but still finds it fascinating that the guillemots survive the great hope. Photo: Leif Eiranson

Over 250 different bird species have been observed on the island. Being on Stora Karlsö makes you forget that around two hundred species a day are extinct. It feels hard to grasp that the amount of birds in the world decreased by 68 percent between 1970 and 2016 when the sky is covered in screaming birds.

15 years ago, Jonas often sat here by himself and noticed guillemot. To his aid, he then needed tourists to catch the cubs.

“But now we don’t need that help anymore. Over 80,000 cubs have been noticed since 1913. Now it is enough that we are just a few researchers on site who make a ring. It also does not bother the guillemot in the same way.

Jonas tucks a kid, headfirst, into a cut-off 1.5 liter pet bottle covered with duct tape. It turns out a homemade scale. He looks at the gauge of the trunk scale, which is attached to one side of the bottle, and exclaims:

– 300 grams. That was a big one!

Then he turns the bottle upside down, shakes it like he’d like to get out the last ketchup stuck in the bottom. In the end, a dazed guillemot falls out onto the pebble beach. It shakes its head a little as it begins to wander towards the water again, surprisingly calmly.

“It may look brutal, but they actually enjoy being in this bottle. It’s dark and crowded. It calms them down.

sea and brids
Out in the sea, thousands of guillemot dads are waiting for their young. Photo: Leif Eiranson

Since humans stopped hunting guillemot in the late 1800s, the birds on the island have no natural enemy. The only mammals that exist are hares, bats and some grazing sheep. Since the decline in environmental toxins in nature, guillemot have thrived.

“The population has actually tripled in just 20 years. It’s quite amazing,” says Jonas.

But last year, something happened that made the guillemots have their worst year ever. When the pandemic hit and tourists disappeared, the population of another bird species on the island increased: sea eagles.

“There have always been a few eagles on the island, but they have never touched the guillemot. But when tourists disappeared in 2020, the sea eagles’ presence increased by 700 percent. At the end of the summer, we observed 33 eagles on Stora Karlsö.

In May, we at Deep Sea Reporter reported on the phenomenon. The researchers found that in 2020, the amount of newborn guillemots decreased by 26 percent.

“2020 was frankly hell for the guillemot, but a paradise for the eagles. Basically the same day that the tourist boat started going out here again, the eagles disappeared and today there are only about three eagles out here, and they are on the other side of the island where neither tourists nor guillemots are.

fåglar på en klipphylla
Up on the rock shelf, the guillemots wait for it to get dark enough for the chicks to jump. Photo: Leif Eiranson

As a biologist, Jonas thought that reality would be more nuanced, that the eagles might get used to the tourists.

“Last year was just a detour in the statistics. Now the guillemots are doing just as well as they did in 2019,” says Jonas.

It’s approaching midnight, but the heat is still palpable. According to SMHI, this year’s June was the warmest ever recorded in several places in Sweden. And the increasingly warmer climate is something that could be a challenge for the guillemots in the future. Jonas himself has noted how the guillemots are affected:

“Some days it gets over 40 degrees on the cliff shelf. It’s way too hot for an Arctic bird like the guillemot. Then you see the kid and the parent panting. The parents knock out their wings and turn their white chest towards the sun, but it can sometimes get so hot that they still have to dive into the sea to cool down.

Some days it can be over 40 degrees on the cliff shelf. It’s way too hot for an Arctic bird like the guillemot. It can cause the cubs to die from heat stroke. Photo: Leif Eiranson

When the cub is left on the shelf, it does not get any shade. It is also exposed to hungry thrushes. But according to Jonas, the big problem is not if the average temperature in the future becomes two to three degrees warmer.

“It’s when there are super heat waves like that that it becomes dangerous. Super warm days like that increase with climate change. A single day like that in an entire season is enough to kill a kid. Last year we had a kid who died after being alone on the shelf for eight minutes. So far, the heat has not killed very many cubs, but if it gets warmer, it can become a real threat to the guillemots.

As the clock approaches 01.00, it has become dark on the beach. The researchers have had time to ring over 160 guillemot chicks. Jumping has slowed down and working with headlamps is something the researchers are trying to avoid.

“The goal is to try to disturb the guillemots as little as possible and the light can confuse them.

We fight our way back the same way we came. I notice how my neck has become stiff from looking up at the mountain for hours on end. A position that my iPhone’s neck is otherwise not so used to.

The guillemots run out to sea as soon as they have recovered from the dramatic fall. Photo: Leif Eiranson

Since the boat to Stora Karlsö only goes twice a day, we sleep over in the few tourist cabins on the island. When I finally lay my head on the pillow, I reflect on the work the scientists actually put in to follow these birds. The fact that, in addition to their daily work, they are on that pebble beach for several hours every night, for two weeks, is admirable.

Outside the window, the song of birds is still heard, but now more in the distance. We have left the window wide open, despite the risk of unwelcome night guests such as harriers and crickets. But it’s too hot to have it closed.

According to Jonas, this could be a record year for the guillemots on the island after last year’s threat, the sea eagle, has made its retreat. Now everything seems to be exactly as it was before the pandemic – even the threat of global warming.

The cubs that the researchers noticed tonight can, if all goes well, live until about 2061. Wonder how Stora Karlsö’s birdsong will sound then?

Text: Fanny Jönsson
Photo: Leif Eiranson

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