An appeal has been made to dog owners to keep their pets on a leash around the protected colony of Little Tern on Gronant Beach.
The call follows an incident in which a dog was filmed crossing the crowded nesting site earlier this week.
The group of Little Terns is the largest breeding colony in Wales.
The beach is internationally known as it contributes over 10% of the entire UK breeding population and complements other colonies.
On Thursday a video was posted to Twitter by the Denbighshire Countryside Service account @GronantTerns of an uncontrolled dog ‘tearing through the settlement’.
The short clip shows vulnerable young chicks not in the air but trying to get out of the way of the dog running at full speed to the nesting site.
@GronantTerns posted: “Great to have the support of @NWPRuralCrime (North Wales Police Rural Crime Team) when there are instances of disturbance, such as an uncontrolled dog tearing up the colony earlier this morning (Thursday). “
“You can see those who are able to fly trying to run away.”
“It’s hard to say how much damage an event like this can do when there are a lot of vulnerable chicks that aren’t yet airborne.”
“We love our four-legged friends, but chicks don’t stand a chance against them. Please keep dogs on a leash.
2/2 It’s hard to say how much damage an event like this can do when there are a lot of vulnerable chicks that aren’t yet airborne.
— Gronant Little Tern (@GronantTerns) June 30, 2022
Little Terns are a Schedule 1 species, which means there is additional protection during the breeding season for dependent birds, nests, eggs and young.
If the birds are disturbed, a person could face an unlimited fine and up to six months in jail.
The Little Tern is the smallest species of tern in Britain, about half the size of a common tern.
They have a yellow beak with a small black tip and a distinctive chattering voice.
Adults weigh just over 50g, as much as a golf ball.
They return to Britain from West Africa in late April to breed on sandy or shingle beaches, spits or small coastal islands.
Gronant beach offers good nesting habitat as it is made up of a perfect mix of pebbles and sand in places.
The local colony has received help from a group of volunteers: the North Wales Little Tern Group.
They have helped service staff at Denbighshire Countryside install four kilometers of fencing on the beach to create enclosures in which the birds can nest safely.
Little terns at the site have also been seen in greater numbers in spring with a recent count recording over 200 adult birds, with nests now confirmed at the site.