Attempted eradication of house sparrows Passer domesticus from Round Island (Mauritius), Indian Ocean

In 1982, house sparrows Passer domesticus were confirmed as having established a naturalized population on Round Island (Mauritius). A planned pending translocation of an endangered Mauritian endemic bird, Mauritius fody Foudia rubra to Round Island suggested eradication of sparrows to be pertinent as they were potentially a resource competitor and vector of parasites and pathogens. An attempted eradication using a combination of techniques was undertaken from 19 August 2008 to 25 February 2009. Following food preference trials, microwave-sterilized millet seed was used as bait for trapping and for narcotisation with alphachloralose. House sparrows were also shot, caught in mist nets and on glue sticks, and some nests and chicks were removed. In total, 320 house sparrows were killed, with trapping accounting for 87% (277) of birds removed. However, the population was not eradicated. The assumption that the Round Island house sparrow population was derived from one storm-driven event and is closed to further immigrants needs to be investigated in order to determine whether long-term eradication is in fact feasible. Suggestions for improving the prospects for eradication or ongoing management of the population are presented.