"To be effective, a chemical repellent must affect the way that the bird perceives the crop."
-Michael L. Avery, National Wildlife Research Center, Gainsville, FL
FlightControl® PLUS in the ultraviolet light spectrum
Humans are able to see colors through three retinal cones that perceive the three primary colors: blue, green, and red. This is termed "trichromic vision". These colors are within the visible spectrum of light (400-700 nm).
Most birds, including geese, have "tetrachromic vision" meaning they have the ability to perceive four colors through four retinal cones. Similar to humans, three of the retinal cones perceive the primary colors. The extra cone perceives ultraviolet light (UV; 200-400 nm).
It is believed that birds use their UV perception to search out food sources and possibly mates. The active compound in FlightControl® PLUS, 9,10-anthraquinone, absorbs UV light. For this reason turfgrass treated with FlightControl® PLUS can be visually recognized by birds.
After one or several encounters with FlightControl® PLUS-treated turfgrass, geese associate the UV-absorbing material on grass leaves with the post-ingestional gut reaction. It is this learned memory response which discourages geese from grazing on FlightControl® PLUS-treated turf. Research has proven that after several encounters with FlightControl® PLUS, birds, including Canada geese, will not eat a treated food source and will seek out non-treated food.