Date of this Version
European starlings (Sturnus vulgaris) nesting in buildings and other structures can cause health, nuisance, and safety problems. We evaluated effectiveness of flashing lights combined with mirrors, and mirrors alone, as deterrents for starlings nesting in starling nest boxes in northern Ohio, 1998-2000. Each year, 100 nest boxes attached to utility poles were randomly assigned equally among 4 treatments (including untreated boxes): 1998- mirrored (internally placed on the back and 2 side walls of nest boxes), mirrored with red-flashing lights, and mirrored with green-flashing lights; 1999-convex mirror above entrance hole, convex mirror at back of nest box, and flat mirror at back of nest box; 2000-mirrors on 3 sides with exposed surface areas of 263 cm2, 527 cm2, or 790 cm2. Starlings nested in 67% (1 998) and 78% (1 999 and 2000) of the nest boxes. In 1998, boxes within the 3 treatments with mirrors, regardless of lights, had fewer nests and fewer nests with eggs, nestlings, or fledglings than did control boxes (P50.002). Boxes with mirrors and lights had fewer (P<0.05) nestlings than mirrored boxes. No difference was noted in number of fledglings/produced nest with nestlings for each treatment. In 1999 and 2000 there was no difference (P>0.25) among the 4 treatments in proportion of nest boxes with starling nests, eggs, nestlings, and young fledged. However, in 2000, boxes with complete mirror coverage did show the lowest occupancy rate of the 4 treatments. Mean dates of first egg, clutch size, number of nestlings, and number of fledglings/nest also were similar (P> 0.06) among treatments. We conclude that mirrors, although slightly repellent under some configurations, are not a practical method to repel starlings from nesting in structures.