South Georgia Habitat Restoration Project — World's Largest Rodent Eradication

Rats and mice, introduced by 18th- and 19th-century sealing and whaling ships, spread across most of South Georgia (a UK Overseas Territory in the sub-Antarctic South Atlantic) and devastated populations of ground-nesting seabirds, including the endemic South Georgia pipit and South Georgia pintail, which had no evolutionary defence against mammalian predators.

The South Georgia Heritage Trust (SGHT), working with the Government of South Georgia & the South Sandwich Islands (GSGSSI), ran three aerial baiting phases using Brodifacoum rodenticide dropped from three Bölkow 105 helicopters: Phase 1 (March 2011, 128 km²), Phase 2 (March-May 2013, 580 km²) and Phase 3 (February-March 2015, 360 km²), together covering 108,723 ha (1,068 km²) — more than eight times larger than any rodent eradication previously attempted anywhere in the world. Total cost was approximately £7.5 million (~US$11 million at 2015 prices), equivalent to about £69.4 (US$104) per hectare.

Extensive post-baiting monitoring found no surviving rodents, and South Georgia was formally declared rodent-free on 8 May 2018. Peer-reviewed research published in Oryx (Cambridge University Press) documented the first confirmed breeding of South Georgia pipits in areas from which they had previously been excluded by rats, with up to four nests recorded in a single bay, and routine pipit sightings across former rat habitat within a year of the final baiting phase.

A single rat was found near a port in October 2014, believed to have come ashore from a visiting vessel rather than representing a surviving population — a reminder that reinvasion risk persists. GSGSSI and SGHT now run an ongoing biosecurity programme, including detection dogs, screening all cargo and vessels calling at South Georgia to protect the restored habitat.

Read the full analysis: https://sght.org/habitat-restoration-project/