Santa Luzia Island - feral cats threaten seabirds
By Caroline Jacobsson, Tue, 09/10/2012 - 09:18
This summer the Portuguese Society for the Study of Bird (SPEA) - our Portuguese BirdLife Partner, carried out a study on feral cat behaviour (feral cats are decendents of domesticated cats that have returned to the wild) and distribution on Santa Luzia Island in Cape Verde in the Atlantic Ocean. The study is part of a proposed project for the removal of feral cats from Santa Luzia aiming the benefit the ecosystem on the island as they are a threat to the seabird population on the island. Santa Luzia is a small uninhabited island with 3500 ha belonging to the Western Cape Verdean islands, declared in 1990 as a Natural Reserve. Santa Luzia is currently only visited by fishermen from the neighbouring São Vicente Island and by researchers. According to local reports cats were recently introduced in Santa Luzia, probably during the second half of the twentieth Century. For 15 days, SPEA’s together with representatives from Biosfera-I, a local association specializing in monitoring and surveillance of feral cats, set up traps in order to catch feral cats in places where these predators have greater activity. After capture, each cat was anesthetized and fitted with a GPS tag. At the end of the 15 day period, six cats were captured. Since then, Biosfera-I technicians are making an effort to recapture the cats and collect the GPS tags. These data will show us the main areas used by Santa Luzia cats to feed, socialization or to rest and will allow a easier and total removal of feral cats in future. During the expedition, there was still opportunity to make an exploration of the island cliffs in search of potential breeding seabirds. This information is lacking for Santa Luzia, with registration of no seabird colony. To our surprise, after 10 days of searching, the first nest was found, with an adult of Madeiran Storm-petrel Oceanodroma castro in incubation position. Although many indicia have been found in other cavities, was not found any other nest. Unfortunately, several feathers, wings and bones of the same species were found in different locations. This survey became even more disturbing when technicians met with about 130 wings of Madeiran Storm-petrel around a single 1om2 site, with clear signs of having been originating from a intensive predation by cats. This fact reinforces the need for immediate action in removing the cats from Santa Luzia Island.