My TL;DR:

More than half the seabird species breeding on British and Irish coasts have declined over the last 20 years, according to the most comprehensive census to date.

Eleven of 21 nesting seabirds species have fallen, five species have remained stable and five have increased, some because of targeted conservation work, according to the Seabirds Count survey.

British and Ireland are internationally important for seabirds, holding most of the world’s nesting Manx shearwaters, northern gannets and great skuas and more than half of the north Atlantic populations of lesser black-backed gulls and common guillemots.

Some species have declined due to climate change reducing food availability and increasing storminess at nest sites, while others have been hit by commercial fishers depleting fish populations and, in some cases, predation on land by invasive mammals such as brown rats.