It is a tropical bird typically encountered between west Africa and India, but last week a western reef heron arrived in north Wales in what is believed to be the first ever sighting in the UK.

The heron was first spotted in Foryd Bay at the weekend before flying to nearby Caernarfon harbour where it fed among the boats.

While the sighting has excited birdwatchers nationwide, experts said it also demonstrated how changing climate conditions have altered the bird’s range.

“The fact that they are getting here in the first place, and then surviving, is likely to be because of increasingly mild winters,” said Nick Moran, training manager at the British Trust for Ornithology (BTO).

“It’s much easier to survive in the winter now than it was 50 years ago because we don’t see shallow water bodies freezing over with any regularity. These herons and egrets typically feed in relatively shallow water.”

A squacco heron, another rare tropical bird typically found in southern Europe and north Africa, was also drawing birdwatchers to Lincolnshire this week. According to the BTO, the bird is only seen in the UK a few times a year.

Alexander Lees, reader in biodiversity at Manchester Metropolitan University and chair of the British Ornithologists’ Union records committee, said the herons were the latest of “what were formerly largely tropical species whose distributions are shifting north with climate change”.

“We are seeing a shift and a readjustment for biodiversity,” he said. “For instance, last year we had the first breeding record of zitting cisticola. It’s a Mediterranean small warbler, and that bird has moved north with climate change. The reason that species didn’t historically breed here is because it’s very sensitive to harsh winters. It couldn’t survive because if we had a prolonged cold spell, they all die. But we no longer get those prolonged cold spells.”

Other notable tropical sightings in the UK over the last few years include the black-winged kite, which first visited in 2023 and has been delighting birdwatchers in Norfolk this year, the brown booby in 2019 and the white-rumped swift, which first colonised Spain from north Africa in the 1960s, spotted in Britain for the first time in 2018.

In 2022, the RSPB said that sightings of European bee-eaters, commonly seen in Africa and southern Europe, were an “unmissable sign” that the nature and climate emergency had reached Britain.

Western reef herons have increasingly been recorded in southern Europe, including Spain and France, and had been expected to be sighted in the UK, Lees said.

Simon Hugheston-Roberts, who first spotted the bird in Wales, told the BBC he was on a walk when he “was lucky to see a small dark heron flying over me on the shore”.

He added: “I’ve spent time birdwatching in Africa and the Middle East, so I’m familiar with a variety of different types of herons, as well as this species.

“So, I applied my knowledge and years of experience of observing birds to inform a process of identification.”

Ian Lycett, who travelled to north Wales to see the bird, told BirdGuides: “That I would be watching a stunning new species for Britain, with the imposing Caernarfon Castle as a backdrop, was not what I initially expected to be doing at the weekend.

“It was a long drive up from London on Sunday morning, but well worth the effort, as the heron offered fantastic views as it fed in the harbour at close range.”

While the western reef heron is similar in size and structure to the common little egret, its blue-grey plumage sets it apart. “They’re very striking,” said Moran. “Unlike anything else we have here in the UK.”

The bird seen in Wales is an adult and likely to have arrived from Europe rather than directly from Africa, although it was impossible to say without tracking the bird’s route. “It could even be a bird that hatched in Europe,” Moran said.

While Moran cautioned against expecting a sudden influx of the species, he said more sightings were likely. “I don’t expect we’ll have dozens of records by this time next year, but I strongly suspect we’ll get more.”

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