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.

Between 2004 and 2010, ICMBio sterilised roughly 450 feral cats on the main island. A 2019 campaign, run as part of a formal cat-management action plan, sterilised 605 cats in 20 days. A parallel adoption scheme has 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 a state law in Pernambuco prohibiting lethal cat control as the central structural barrier: management has followed a mainland urban model of sterilisation and veterinary care rather than an island-eradication approach, and researchers conclude this has not delivered measurable conservation outcomes. This practice is included as a documented cautionary case: sterilisation-only control, however well monitored, has not matched the results achieved elsewhere by lethal eradication combined with biosecurity (e.g., in Seychelles or French Polynesia), and ICMBio researchers have called for an integrated, revised strategy.

Read the full analysis: https://www.perspectecolconserv.com/en-management-cats-rodents-on-inhabited-articulo-S253006441830110X