Bass Rock ‘bounces back’ after bird flu – BBC News

Bass Rock 'bounces back' after bird flu - BBC News

image source, Nature Picture Library

image captions,

There are signs of a much improved breeding season among the gannets in Bass Ross

The world’s largest heron colony on Bass Rock in the Firth of Forth appears to have recovered after being decimated by bird flu, scientists say.

Thousands of birds died last year after contracting the virus in the middle of the breeding season.

Researchers from the University of Edinburgh are conducting a population survey using drones and artificial intelligence to count the numbers.

But there are signs of a much better breeding season this year.

Bass Rock’s colony of northern gannets – Europe’s largest seabird – grew from about 4,000 breeding pairs in 1960 to more than 75,000 until last year – or about 150,000 birds during the breeding season.

A recent study found that the survival of fully grown birds between 2021 and 2022 was lower than The average value 10 years ago was 42% due to bird flu.

A photo comparing the density of gannets on the rocks shows fewer birds, with concerns that the destroyed population may not be sufficient to maintain the colony.

But scientists and staff at the Scottish Seabird Center in North Berwick are optimistic that once the current survey is completed, numbers will rebound significantly.

‘Better Than Ever Hoped’

Maggie Sheddan, a volunteer at the center for more than 20 years, visits the island weekly.

“It’s really amazing to see, because this colony was destroyed last year,” she told BBC weather editor Justin Rowlatt.

“We don’t know how we came out this year, there are still gaps, but many couples survived and came back.

“We were confident they would survive last year, but we don’t know. There’s no question it’s better than we ever hoped. To see so many established breeders is great.”

Mrs. Sheddan said that last year in an area where there were only 2-3 birds, last year there were “100 -200” each.

image source, Getty Images

image captions,

Bass Rock is home to the world’s largest colony of northern gannets

The presence of ‘weak’ birds on the rocks – those three or four years old – is evidence of “almost the birth of a new colony”, she said.

With three nests per square meter at its peak, and birds returning to the same spot each year as their “territory”, the previously vacant area is popular with newcomers.

“We haven’t seen young birds on the rocks for years, so it’s exciting,” Sheddan said. “We have established breeders and single birds who have lost their partners, but still own a Territory.

“But you’ve got new birds flying around, ‘Oh look there, I’ve never seen that gap before.’

“What we’re seeing now is what appears to be a healthy colony. It’s going to be really amazing to see it settle down and break up.”

‘Stages of Death’

Miss Sheddan remembers the day she visited the Rock last summer, when there were reports of bird flu spreading to the east coast of Scotland from Shetland.

“It’s heartbreaking,” she said. “We knew it was happening, we found dead birds on the beach.

“The lower part of the rock was still covered with gannets, but when we arrived and they were all gone, which they do when they are not breeding, I saw that there were sick people among them.

“I unlocked the door and behind it were gannets five or six deep, in various stages of death.”

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A dead gram’s corpse littered Bass Rock last summer

Ms Sheddan explained that gannets are “arrogant” birds that will attack even when injured – but on this visit she said it was like the birds couldn’t see her.

She said: “Some people are hanging by the head, some people are fit – their whole body is hit, their head is moving forward, when they have the virus, they can’t control it, it’s the nervous system, they just flop.

“I went up to the main colony and found about 40 dead. Then I thought, ‘OK, we’ve got it’.

“I collected a number of samples to take down and then I had my moment: ‘Oh, my goodness, I’ve seen this colony grow for 20 years, and I think I’m going to see this colony die in front of my eyes’. This is scary.

“Every time I go up, there are more dead birds, the rocks are empty, it hurts my heart, because the gannets are strong, the birds are dying in the nest. One of them died with a mummified egg under it.”

Recently, a team of experts was allowed to conduct blood tests on gannets to investigate their health and eye color.

It found that birds with black irises instead of the usual pale blue survived the bird flu.

image source, Rebecca James

image captions,

Gannet with black irises was first seen on the island in June 2022

Amy Tyndall and Tom Wade from the University of Edinburgh’s School of Geosciences are conducting population surveys using drones.

Ms Tyndall said they were trying to use AI to detect live and dead birds on rocks and which sits in the automatic nest because “humans make more mistakes”.

The team hopes to report their findings in the coming months.

On the scene – BBC weather editor Justin Rowlatt

Scientists on their latest fact-finding mission to Bass Rock sent a drone to capture aerial photos of gannets – but you don’t need the AI ​​system they used to see how thousands of birds have returned to the rock.

The falling birds were covered by a large moving cloud of soaring birds. Their fierce arguments can be heard even above the sound of the ship’s engine.

The Gannet is Britain’s largest seabird. They were confident and aggressive and squawked and pecked me as I walked up. From the road from the stone parking lot.

Many birds are defending their nests, most of them complete with ugly chicks.

image source, James Glossop

But there are thousands of single species of birds. Gannet mate for life. These birds are waiting for a partner who almost certainly will not return.

It is clear that the population has taken a huge hit, but Maggie Sheddan of the Scottish Seabird Center is optimistic for the future.

She said it may take a decade or more, but the colony will recover.

The gannets of Bass Rock will survive.

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