An island in Belmont Reservoir is now home to the UK’s largest colony of a protected species of gull.

More than 11,500 breeding pairs of black-headed gulls reared over 10,000 young at the reservoir this year, which is a record for the site.

The achievement is the result of two decades of conservation work by United Utilities estate staff working alongside experts and countryside regulator Natural England.

Ornithological consultant Stephen Martin said: “Even going back to before the 1990s, birds were breeding there in small numbers and were being encouraged by the water company, but in the summer, when water levels were lower the island became a promontory and predators kept the numbers down.

“The big difference came when United Utilities deepened the channel in 2010 and created an isolated island so foxes and rats could no longer get to the eggs and young.

“It’s now a really important colony and one in 14 of all Britain’s breeding pairs come here to Belmont.

“When they’re nesting it’s amazing to see and hear. It’s one of nature’s great wildlife spectacles.”

The colony is particularly important as the black-headed gull has been in decline for the last 25 years.

Mr Martin said: “The young will tend to come back to their birthplace to nest if the site is still suitable, hence the growing numbers show our work is clearly suiting them.

“There is plenty around for them to eat, such as invertebrates like worms, beetles and flying ants.

“Once the young have fledged they scatter across the whole country but many will stay in the north west.

“Every year there’s lots of press about seabird colonies failing so we are always quite relieved when our gulls have been successful and departed. Then the whole process starts again next year.”