The article offers information on the gizzard shad, a favorite food fish of diving ducks, cormorants and pelicans. Gizzard shad is the organism behind the chaos when fish boil at the water's surface and are then chased by birds. It belongs to the same family of Clupeidae together with seven other North American freshwater species of herrings and alewife. It indicates that Colorado shad average smaller and its depletion over a cold winter may cause the absence of rare birds on a water body.