Warning: this article contains graphic images.

Mice have crossed the line. After years of appearing cute, the diminutive nibblers have gone into beast mode by attacking adult albatrosses in the South Atlantic and feasting on the brains of their chicks.

Graphic videos and photographs released by the British wildlife charity Royal Society for the Protection of Birds (RSPB) reveal gangs of the rodents swarming the nests of critically endangered Tristan albatrosses on Gough Island in the South Atlantic Ocean and eating chicks alive, while also inflicting often-fatal bite wounds on the young seabirds’ parents.

Attacks, which are carried out by groups of up to nine mice, have become so devastating that conservationists fear it could hasten the extinction of the species.

Mice have previously been recorded attacking nesting albatrosses on Midway Atoll, and chicks on Gough Island, but this is the first time footage has captured them going after the adult birds on Gough Island.

Albatross chicks are an easy target for mice as they are left alone over winter. RSPB

The mice are not native to the remote island, a British overseas territory, but were accidentally introduced by sailors in the 19th century. Since then, the once ordinary house mice have adapted to their new environment, expanding in size and developing a taste for seabirds.

Gough Island hosts one of the largest seabird colonies on the planet, and is home to 22 different species. Some 10 million birds inhabit the island, although just 2,000 Tristan albatross pairs remain.

Conservationists fear that mice could wipe out some seabird species on Gough Island. Image: RSPB

Senior Gough Field Assistant Chris Jones said in a statement that “we have known for more than a decade that the mice on Gough Island attack and kill seabird chicks. While this is already of great concern, attacks on adults, which can produce dozens of chicks in their lifetime, could be devastating for the population’s chances of survival.”

Capable of attacking chicks up to 300 times their body weight, the mice have got used to preying on the young of albatrosses and petrels, as they are left alone over winter and are therefore an easy target. Given that albatrosses mate for life and produce one egg every two years, the loss of these chicks poses a major threat to the survival of the species. And with deadly attacks on adult birds now escalating, reproduction rates are also likely to plummet.

Mice have apparently developed a taste for chicks' brains. Image: RSPB

The effects of this behavior have already become alarmingly apparent, with mouse predation resulting in 2 million fewer seabird eggs and chicks on Gough Island each year. To curb the impact of these blood-thirsty devil-vermin, the RSPB is planning to exterminate all mice on the island in 2020. And you have to say, they kind of deserve it.