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

Rats and mice, introduced to South Georgia (a UK Overseas Territory in the sub-Antarctic South Atlantic) by 18th- and 19th-century sealing and whaling ships, spread across most of the island and devastated ground-nesting seabird populations, 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), set out to eradicate invasive rodents across the island to allow native ground-nesting bird populations to recover.

Three aerial baiting phases used 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 hectares (1,068 km²) at a total cost of approximately £7.5 million (~US$11 million at 2015 prices), or 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 documented the first confirmed breeding of South Georgia pipits in areas previously 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 found near a port in October 2014 — believed to have arrived on a visiting vessel rather than indicating a surviving population — underscored that reinvasion risk persists. GSGSSI and SGHT now run an ongoing biosecurity programme, including detection dogs and screening of cargo and vessels calling at South Georgia, to protect the restored habitat.