Efficacy of a Laser as a Starling Deterrent and its Effect on Lactating Dairy Cow Behavior
2026-03-24
Callan A. Lichtenwalter et al.
European starlings ( Sturnus vulgaris ) cause damage (including structural damage) on dairies, eat cattle feed, and can potentially spread disease through their fecal matter. Deterring starlings from dairies without affecting cow ( Bos taurus ) welfare is vital, and lasers have been effective starling deterrence tools in urban roosts and in some crops. To evaluate if the use of lasers on dairies would affect starling use of freestall barns as night roosts, or lactating cow behavior, 1 laser was installed in each of the 2 freestall barns at the Knott Dairy Center at Washington State University, Pullman, Washington, USA. Lasers were turned on or off in both barns once a week on a set schedule. Starling counts occurred twice a week at sunset for a baseline week and 2 subsequent 4-week periods, in November 2022 and January 2023. CowManager Sensor activity monitoring ear tags were used to monitor lactating cow behavior during the entire study. Pen 1 and pen 2 had more birds in the final week of the study (1,108 birds and 325 birds, respectively) than during the baseline week (783 birds and 181 birds, respectively). No meaningful patterns emerged from the cow behavior data, so we concluded that the lasers did not have an effect on cow behavior. From this study, we were not able to conclude that the lasers were effective at deterring starlings from roosting in the freestall barns overnight, but a few simple adjustments to the laser may improve its efficacy in future studies.