Thousands of starlings swooping and diving in formation around a bridge in Belfast is no longer a regular sight – and light pollution may be the reason.
The spectacular winter aerial display, known as a murmuration, could be seen most obviously above the Albert Bridge and often attracted large crowds.
But fewer and fewer displays were noted in recent years and none reported this winter.
New LED lighting was installed above the bridge in December 2019, but it met all safety and environmental standards, the Department for Infrastructure said.
Murmurations happen in the winter time as the starlings group and move together for warmth and safety.
Conservationist Conor McKinney told BBC’s Good Morning Ulster Belfast was once one of the best places in Ireland to watch such a display.
"Murmurations are something starlings do in really cold weather to try and stay warm. If you have milder, more temperate winters, you lose the murmurations," he said.
"We can rule this out as the root cause, however, since there are still murmurations throughout the island of Ireland and Great Britain.
"Light pollution has a direct physiological impact on the birds. It causes extra stress, exposure and prevents them from sleeping."
Anne-Marie McDevitt, of RSPB NI, said starlings, a red-listed species of high conservation concern, have declined in numbers by two-thirds across the UK since the mid 1970s.
"Roosting together in large numbers is really important for starlings - in these large flocks there is safety in numbers from aerial attacks from birds of prey, and it's thought that when starlings gather they also exchange information about vital food sources," she said.
She said all government departments had a statutory duty to further biodiversity.
"That and the fact the starling is on the government's own priority species list means that the needs of starlings should have been taken into account when carrying out any works on or close to the bridge," she said.
"The starlings can still come back, we'd like to know what is going to be done to make this happen".
"The street lighting on the road and footways above the bridge were converted to LED in December 2019," a DfI spokesperson told the BBC.
"This lighting was designed in accordance with the current British Standard, BS 5489-1:2020 Design of Road Lighting and meets all of the required British and EU safety and environmental standards."
