Increasing use of exotic forestry tree species as refuges from nest predation by the Critically Endangered Mauritius fody Foudia rubra

Abstract

The population of the Critically Endangered Mauritius fody Foudia rubra fell by 55% over 1975–1993 because of habitat destruction and predation. The species was believed to be dependent on a small grove of introduced, non-invasive Cryptomeria japonica trees that offered protection from nest predation. We investigated the current population size and distribution of the fody and compared nesting success in forestry plantations to that of a released population on an offshore island. The population size on the mainland has remained stable over the past 10 years, with increases in pine Pinus spp. plantations, but continues to decline in areas of predominantly native vegetation. Only 16% of pairs found were estimated to nest in native tree species. Up to 81% of nest failures on the mainland were attributed to predation but nesting success in C. japonica and pine trees was similar to that of a released population on a predator-free offshore island. The mainland population is increasingly dependent on plantations for survival and we predict this will continue. Management and protection of non-invasive exotic species, together with creation of native habitat refuges on the mainland and offshore islands can be used to increase numbers of threatened birds in areas where predator control is not feasible.