Green roofs are a technology with a long tradition however, today are considered one of the most innovative developments for urban greening and constitute an opportunity for creating additional habitat for birds in the cities. Green roofs provide water and food mainly throughout insects, berries and seeds for feeding birds. Also provide space and cover that protect birds and their nests from predators. However, not all green roofs have the same ecological valueor equally favour the breeding of birds. It depends on the type of green roof, design, selected vegetation and maintenance. This encourages bird presence including of endangered species that permits urban people to obtain benefits such as aesthetic and psychological, ecological and some utilitarian ones. Conversely at the same time birds can damage plants that vegetate on green roofs especially in its establishment phase when the vegetated structure is more fragile or more rarely can act as disease reservoirs or cause accidents, e.g., in the airport environments. Despite the worldwide increasing wide spread of green roofs in the last decades until now little attention has been paid to bird populations in relation to this kind of urban greening and few specific studies have been undertaken. This study carries out a broad review on green roofs as a habitat for birds in the urban environments and proposes a standardised methodology aimed at studying bird population on green roofs.