The last twenty-four hours on Fernando de Noronha have been non-stop, non-sleep, and action filled, and not just because it’s been Carnival in Brazil. While the huge influx of tourists enjoy a long holiday break, we’re hard at work on our survey of invasive rats and other species on this tropical island.
We woke first thing early in the morning to visit Atalaia, a huge natural rock infinity pool only accessible at low-tide which contains an immense diversity of marine life.
Access to Atalaia is by advance reservation only and visits are strictly limited to small groups for only 30 minutes at a time, and monitored by the Instituto Chico Mendes de Conservação da Biodiversidade (ICMBio). As we take our turn dozens of other tourists are queuing, hoping to secure a spot many days in advance. In the crystal clear waters of the pool we count many of the different fish of the island.
After this we head down a dirt road in the afternoon to an isolated native forest patch to set up what it seems should be a simple rat live-trapping grid to estimate the density of rats on the island using a”spatially explicit capture-recapture” (learn more about the technique). Instead we find ourselves crawling around on our hands and knees tangled in vines and trying not to be bitten by a new invasive ant species on the island. As well as carnival coming to town, so too it seems has the wet season, and the heavens open up upon us.
As the evening comes we are invited by one of Brazil’s most successful NGOs, TAMAR, to participate in a night patrol monitoring turtle nesting on one of the most popular beaches in Brazil–Praia de Leão. With the beach to ourselves under the moonlight, the rain having finally abated, we patrol the beach in darkness every hour from dusk till dawn looking for fresh turtle signs. Success comes and we find a massive green turtle (Chelonia mydas) never previously recorded on the island, and in the dawn light a second equally large female green turtle digs her nest with painstaking precision before laying her eggs.
As day breaks we return to the rat-trapping grid to see how the night fared in the forest. The rain also returns and we are once again soaked through, as are five rats in our traps representing a staggering nearly 50 percent trap success rate.
We mark each rat with an individual ear-tag for identification and release it back in to the forest. Over the next five days we’ll continue to visit the traps and see what our recapture rates of these rats are, but for now, I plan to catch up on some much needed sleep.