Dunnock two or three adjacent female territories overlap one male territory, and so polygyny is favored, with the male monopolising several females. Polygynandry also exists, in which two males jointly defend a territory containing several females. Polyandry, though, is the most common mating system of dunnocks found in nature. Depending on the population, males generally have the best reproductive success in polygynous populations, while females have the advantage during polyandry. Studies have illustrated the fluidity of dunnock mating systems. When given food in abundance, female territory size is reduced drastically. Consequently, males can more easily monopolise the females. Thus, the mating
Common black hawk distinctive piping "spink-speenk-speenk-spink-spink-spink". The common black hawk is protected in the far north of its range (in the USA) under the Migratory Bird Treaty Act of 1918. Common black hawk The common black hawk ("Buteogallus anthracinus") is a bird of prey in the family Accipitridae, which also includes the eagles, hawks, and Old World vultures. It formerly included the Cuban black-hawk ("Buteogallus gundlachii") as a subspecies. The mangrove black hawk, traditionally considered a distinct species, is now generally considered a subspecies, "B. a. subtilis", of the common black-hawk. The adult common black-hawk is long and weighs on average. It has