Night Birds Returning — Gwaii Haanas Invasive Rat Eradication (Haida Gwaii, Canada)

Rats introduced by maritime shipping since the late 1700s spread across at least 18 islands of Haida Gwaii, British Columbia, becoming the single largest threat to the ecological integrity of Gwaii Haanas National Park Reserve. Approximately half of the world's population of Ancient Murrelets, a species at risk in Canada, breeds on these remote islands.

In 2009, Parks Canada and the Council of the Haida Nation launched "Night Birds Returning", a five-year, roughly C$2.5 million joint eradication programme with Island Conservation, Coastal Conservation, Simon Fraser University and the Laskeek Bay Conservation Society. Ground-based trapping and baiting removed rats from Arichika and Bischoff islands from 2011; in 2013, Canada's first aerial distribution of rodenticide bait cleared Murchison and Faraday islands, both subsequently declared rat-free.

Following the aerial phase, Parks Canada and partners documented early signs of ecological recovery, including increased nesting attempts and successful chick-rearing among Black Oystercatchers, used as a sentinel species for coastal ecosystem health.

The programme also illustrates the limits of island eradication without permanent biosecurity: by 2016 Parks Canada confirmed that rats had reinvaded at least one previously cleared island, most likely via debris or vessel traffic, requiring renewed monitoring and control effort. The case is a partial, evidenced success — real, measured biodiversity gains on cleared islands, tempered by a documented reinvasion.