Effects of laser power and exposure time on the avian eye: implications for the use of bird deterrents

Laser deterrents have been used as a method of deterring birds from problem areas such as fisheries, agricultural fields and airports. This method is considered a nonlethal means of control although lasers are known to cause visual lesions and loss of visual acuity in humans and other animals. Birds have a complex visual system which is necessary for behaviors critical to their survival, such as hunting and foraging, and predator vigilance. The purpose of this study is to determine the safety of laser deterrents for avian eyes using two species of birds: house sparrows (Passer domesticus) and European Starlings (Sturnus vulgaris). We found evidence that laser exposure can cause corneal edema, cataracts, retinal atrophy, displacement of the photoreceptor nuclei, and degeneration of the scleral cartilage. The laser exposure time was an important factor in the likelihood of developing corneal edema and retinal atrophy in starlings. Our findings suggest that lasers may not be completely safe for use as bird deterrents, but further research should be done to find possible solutions to improve laser safety from the avian viewpoint.