Propagule size and patterns of success in early introductions of Chukar Partridges (Alectoris chukar) to Nevada.
Background: In an effort to combine the well-known evolutionary phenomenon of increased extinction probability in small populations with invasion biology models, some studies have concluded that propagule size is the primary determinant of establishment success in introduced birds. Question: Is establishment success in Chukar Partridges (Alectoris chukar) introduced to the state of Nevada predicted by propagule size, by location of release, or by the source (game farm or wild-caught)? Methods: We compared propagule sizes of successful and unsuccessful introductions of Chukar Partridges in Nevada, using logistic regression. We included tests for possible differences across introduction sites (i.e. counties) and between birds that originated from game farms or were wild-caught. Findings: Propagule size was not a significant predictor of introduction success. Moreover, we found no significant differences across 17 sites, or between wild birds and those from game farms. Conclusions: It appears most likely that site-level factors such as the availability of habitat are more important to the success of introductions than is propagule size.