More than 600 dead Arctic tern chicks have been collected at the biggest mainland breeding colony in the UK following an outrbreak of bird flu.
National Trust rangers initially recorded 2,600 eggs for the peak breeding season at Long Nanny in Northumberland – but within the past two weeks discovered dying chicks.
A number of dead adult seabirds have also been collected from the site.
It is feared the population of rarer little terns could also be infected.
James Porteus, lead ranger at the site near Beadnell said: “The season started so well, with over 1,600 pairs of Arctic terns returning to breed this season – the highest number of breeding pairs at the site since 2018.
“But, a couple of weeks ago, we started to notice that some of the chicks were dying and since then we have picked up over 600 dead Arctic tern chicks from across the site.
“We have also started to discover some dead adults now which is equally heart-breaking and worrying.”
It is feared an infected bird may have got into the colony and passed on the deadly disease.
The six rangers working round the clock fear the impact of bird flu could undo population gains made in recent years.