Now their appetite for the eggs and chicks of ground-nesting birds such as the South Georgia pipit and pintail is threatening the survival of these endemic species.

BBC: South Georgia rat cull begins again

According to the US Geological Survey, the American Buff-Bellied Pipit is 5.5in (14cm) in length and is usually found in flocks in ploughed fields, shores and tundra.

BBC: American Buff-Bellied Pipit

In addition, with cuckoos laying their eggs in other birds nests, there may be issues with their key hosts, such as the meadow pipit and dunnock, being in decline.

BBC: Cuckoo's call becomes rarer in UK

For ground-nesting birds like the South Georgia pipit and South Georgia pintail, both of which are unique to the island, the rat explosion spells disaster because the rats feed on chicks and eggs.

BBC: Rat eradication project on South Georgia set to resume