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Rat Eradication on Ilha do Meio

In Brazil WWF is partnering with TRIADE to undertake a trial rat eradication on Ilha do Meio, one of the small offshore islands of Fernando de Noronha. I visited the island this week so that the team undertaking the project could bring me up to speed on their progress so far. Fernando de Noronha is a large inhabited archipelago lying 345 km north east of Brazil just below the equator in the Atlantic Ocean. I’ve been studying the population dynamics of invasive rats on the main island for three years as part of a CAPES PVE project.

A baby masked booby on Ilha do Meio, Fernando de Noronha
A baby masked booby on Ilha do Meio, Fernando de Noronha (Photo by James Russell)

On the main island, however, rat eradication is not currently possible, due to the large population size and complexities of other invasive species present. Ilha do Meio is one of the smaller uninhabited islands lying to the north east. At only 16 hectares it is a perfect size for the Brazilian team to trial rat eradication methodologies and develop national capacity for invasive species management. The island is also an important breeding site for seabirds which would stand to benefit from the black rat (Rattus rattus) eradication.

The razor sharp under cut coastline of Ilha do Meio, Fernando de Noronha
The razor sharp under cut coastline of Ilha do Meio, Fernando de Noronha (Photo by James Russell)

Despite its small size though, I am quickly reminded how challenging any rat eradication can be. The island is composed of raised and undercut rock, making landing at the most accessible site still treacherous. We are thrown on the rocks and with gloves scale the razor sharp outcrop. The plateau provides no further relief being only a dry exposed expanse of more rock and some low lying herbs. As we walk around the landscape it is only broken up by the white heads of nesting masked boobies (Sula dactylatra), and the 20 metre grid of rodent bait stations.

A rat bait station designed for use Ilha do Meio, Fernando de Noronha
A rat bait station designed for use Ilha do Meio, Fernando de Noronha (Photo by James Russell)

As well as trialling rat eradication methods, the team are also monitoring components of the ecosystem. Censuses of resident land and seas birds, and the charismatic mabuya (Trachylepis atlantica), are being undertaken to monitor responses to the eradication methodology itself, as well as to the cessation of rat predation and competition across the island. The team will continue their research over the rest of the dry summer season which provides the best timing to target the rats for eradication.

A mist net set in the tiny forest fragment on Ilha do Meio, Fernando de Noronha
A mist net set in the tiny forest fragment on Ilha do Meio, Fernando de Noronha (Photo by James Russell)

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