European Starling Nest‐site Selection Given Enhanced Direct Nest Predation Risk

The European starling (Sturnus vulgaris) is recognized, outside its native range, as an invasive species, and efforts to deter its nesting have generally been unsuccessful. Enhancing perceived risk at the nest site is a little-explored route in developing a nest deterrent. Specifically, nest predation risk affects site selection, reproduction, antipredator behavior, and fitness in nesting birds. We questioned whether perceived predation risk as related to a snake model positioned inside a nest box, in striking form, moving, and present throughout the period of cavity site selection would induce European starlings to avoid or delay nest construction. We conducted our study on the 2,200-ha National Aeronautics and Space Administration Plum Brook Station (PBS), Erie County, Ohio, USA. Our objectives were to examine nest initiation, clutch development, and hatching success by starlings relative to 4 nest-box treatments: moving snake model, movement mechanism only, immobile snake model, and control (empty box). We applied treatments across 120 nest boxes on PBS (30 boxes/treatment) from 15 April through 17 June 2019. We observed no treatment effects on nest initiation or date of nest bowl formation. Starlings occupied (laid >= 1 egg) in 76% of nest boxes (moving snake model = 22 boxes, movement mechanism = 25 boxes, immobile snake model = 21 boxes, control = 23 boxes). We observed no effects of treatment on likelihood of starlings laying a clutch, date of first egg, clutch size, or hatching success. We suggest that starlings adapted to perceived risk because models, despite animacy, did not attack. Therefore, snake models, as developed herein, are ineffective starling nesting deterrents. Published 2021. This article is a U.S. Government work and is in the public domain in the USA.