Fernando de Noronha Feral Cat Management — A Cautionary Case in Predator Control

Fernando de Noronha, a UNESCO World Heritage marine national park off Brazil's north-east coast, hosts the endemic Noronha skink and remnant seabird colonies now largely restricted to small offshore islets free of cats and rats, after historical predation collapsed breeding on the main island.

ICMBio's cat-management programme aims to reduce feral cat predation on native and endemic wildlife through sterilisation and relocation, operating under a formal action plan and constrained by a Pernambuco state law that prohibits lethal cat control.

Between 2004 and 2010, ICMBio sterilised roughly 450 feral cats on the main island. A 2019 campaign sterilised 605 cats in 20 days. A parallel adoption scheme relocated cats to mainland Brazil, though a published case study reports this achieved only 10-20 cats relocated.

Despite these efforts, a 2015 distance-sampling survey estimated the resident cat population at 1,287 animals, and 2015-2017 live-trapping recorded black rat densities of around 37 per hectare in forested habitat. Researchers documented continuing cat predation on the Noronha skink, worm lizard and seabirds — including at least 11 predated red-billed tropicbird carcasses found in 2014-2015 alone — with a masked booby colony reduced to fewer than 20 pairs and red-billed tropicbirds to fewer than 10 individuals at one monitored site.

The published case study identifies Pernambuco's state law against lethal control as the central structural barrier: management has followed a mainland urban sterilisation model rather than an island-eradication approach, and researchers conclude this has not delivered measurable conservation outcomes. ICMBio researchers have called for an integrated, revised strategy, noting that sterilisation-only control has not matched results achieved elsewhere (e.g. Seychelles, French Polynesia) through lethal eradication combined with biosecurity.