Low Occupancy Rates of Artificial Nest Cavities by European Starlings

Abstract

European Starlings (Sturnus vulgaris) are known for their generalist ecological requirements and compete for available cavity nest sites with native species.  Our purpose was to revisit recent findings with regard to Starling selection of artificial nest structures.  In previous studies involving Starling use of wooden nest boxes in northern Ohio, USA, Starling occupancy across sites ranged from 67% to 100%; use by native species was minimal.  In this study, we made available 25 wooden boxes and 25 PVC nest tubes for Starling nesting, but we were forced to forego planned treatments because of low Starling occupancy rates.  We found a maximum occupancy rate of 40% for Starlings, whereas Eastern Bluebirds (Sialia sialis) and Tree Swallows (Tachycineta bicolor) had a combined minimal occupancy rate of 52%.  We speculate that an increase in availability of dead ash trees (Fraxinus spp.) due to damage by the emerald ash borer (Agrilus planipennis), as well as a potential increase in natural cavities due to an increasing Red-bellied Woodpecker (Melanerpes carolinus) population might explain our findings.  With potentially fewer Starlings selecting artificial structures native species might now exploit these artificial nest sites.