An irruption interrupted: eradication of wild turkeys Meleagris gallopavo from Santa Cruz Island, California

Eradication of introduced species is often necessary to conserve native biota on islands. Seven wild turkeys Meleagris gallopavo were introduced to Santa Cruz Island, California, in 1975 and the population began to irrupt in the early 2000s. Turkeys posed a variety of threats to native species, including that they could replace the previously eradicated population of feral pigs Sus scrofa as a prey subsidy for golden eagles Aquila chrysaetos, which through incidental predation had driven three subspecies of island fox Urocyon littoralis to near extinction. We implemented a four-phase programme to eradicate the turkey population, based on general principles for eradication efforts. For example, we focused on preventing individual turkeys from becoming aware of our methods, which increased the likelihood we would be able to detect and dispatch all of the birds. Leveraging the tendency of turkeys to aggregate during winter, we used baited drop nets, precision shooting, and monitoring of surgically sterilized, radio-telemetered 'Judas turkeys' to eliminate the population. We estimate the population comprised 310 individuals when the project began in 2006 and that the last bird died in December 2012. Methods used in this project could be applied to other alien bird eradication programmes, of which there are few examples in the scientific literature.