A well documented case of how birds use a green roof is located in Lancashire (UK): the grass roof on the visitor centre at the Wildfowl and Wetland Trust reserve at Martin Mere. Mallards regularly breed on this particular green roof. Mallards (Anas platyrhynchos), skylarks (A lauda arvensis) and various finches and thrushes have all used the green roof.
Another example is the green roof of the Ford Motor Company’s River Rouge Assembly Plant in Dearborn, Michigan (USA) where two species have been found using it: olive sided fly catcher (Contopus cooperi) and killdeer (Charadrius vociferus).
Similarly, several bird species including a falcon (Falco sp.), regularly alight and even nest on the Ecover factory green roof in Belgium.
Large-scale green roofs have been implemented at O’Hare International Airport at Chicago (USA) and have attracted birdlife. Most of the birds using these green roofs were killdeer, European starlings (Sturnus vulgaris) and mourning doves (Zenaida macroura). Killdeer nested on green roof whereas the other species were perched or loafing.
It has been reported 25 bird species on several green roofs in Switzerland. Up to 26 bird species have been monitored at the Augustenborg Botanical Roof Garden in Malmo (Sweden) that is the world’s first botanical roof garden and that is located atop the Scandinavian Green Roof Institute. Fifteen of these species successfully nest on the green roofs.
Some projects of green roofs are developed to create protective habitats on the roofs for bird species of interest. The most emblematic case is that of the black redstart (Phoenicurus ochruros) that is one of the species for which in England it is developing a specifically designed green roofs called eco roofs which provide habitat in densely built-up areas for endangered bird species. The black restart is rare in the United Kingdom. There are only between 50 and 100 breeding pairs that are fully protected, although his habitat, restricted to industrial and post-industrial sites in several British cities is not. A Species Action Plan identified green roofs as the potential solution to replacement habitat in the breeding localities of this species. Green roofs were designed to mimic the conditions found on the derelict sites favouring the black redstart. The built and planned green roofs designed to benefit black redstart are estimated in 15,000 m2.
The project of green roofs at University Hospital of Basel, Klinikum2 (Switzerland) is other experience in which is demonstrated the possibility of creating new habitats for migratory species and species that suffered the loss of their habitat. In arecent study of the University of Applied Sciences in Wädenswill (Switzerland) over a variety of five flat-roofed green roof projects in different regions of Switzerland has been identified appropriate habitats for endangered bird species. Three ground-nesting bird species of Switzerland, the skylark, the northern lapwing and the little ringed plover (Charadrius dubius), have been affected by urban development but have been observed on green roofs. Even though each of these species has slightly different habitat requirements in terms of food supply, nesting and breeding, both of these habitats have been recreated on green roofs.