Urban green roofs provide habitat for migrating and breeding birds and their arthropod prey

Abstract

The world is rapidly urbanizing, and many previously biodiverse areas are now mostly composed of impervious surface. This loss of natural habitat causes local bird communities to become dominated by urban dweller and urban utilizer species and reduces the amount of habitat available for migrating and breeding birds. Green roofs can increase green space in urban landscapes, potentially providing new habitat for wildlife. We surveyed birds and arthropods, an important food source for birds, on green roofs and nearby comparable conventional (non-green) roofs in New York City during spring migration and summer breeding seasons. We predicted that green roofs would have a greater abundance and richness of both birds and arthropods than conventional roofs during both migration and the breeding season for birds. Furthermore, we predicted we would find more urban avoider and urban utilizer bird species on green roofs than conventional roofs. We found that both birds and arthropods were more abundant and rich on green roofs than conventional roofs. In addition, green roofs hosted more urban avoider and utilizer bird species than conventional roofs. Our study shows that birds use green roofs as stopover habitat during migration and as foraging habitat during the breeding season. Establishing green roofs in urban landscapes increases the amount of habitat available for migrating and breeding birds and can partially mitigate the loss of habitat due to increasing urbanization.

Biodiversity Impact of Green Roofs and Constructed Wetlands as Progressive Eco-Technologies in Urban Areas

“…For birds, urban avoider species were more frequent on the green than conventional roofs in New York [57]. Moreover, extensive roofs hosted birds feeding on more food types than intensive roofs [55], showing the benefit green roofs can provide within densely built landscapes.…”

“…Nonetheless, extensive roofs hosted more bird species than semi-extensive roofs [55] and brown/biodiverse roofs supported more invertebrate species than green roofs [56]. Conventional roofs, which can be seen as being the harshest of all roofs, supported fewer species of birds and arthropods than green roofs [55,57] but equal richness of bats [58,59] and birds [59] foraging on roofs. Overall, it can be expected that conventional roofs are less rich in plants and animals [23] but highly mobile taxa, such as bats and birds, might show no preferences in their use of roofs if these provide food or nesting resources.…”

“…In comparison to conventional roofs, Williams et al [23] suggest that green roofs should support a greater abundance of species. Indeed, bird and arthropod abundance was higher on the green than conventional roofs in New York [57]. A natural green roof, with structurally rich equipment in the form of deadwood, mocks, stones, different substrates, water surfaces, nesting, and shelter facilities, serves to increase and to preserve biodiversity [81].…”

Perception and Barriers to Implementation of Intensive and Extensive Green Roofs in Dhaka, Bangladesh

“…According to the study, a flat roof generally results in the best average shielding from noise pollution. Green roofs that are designed using local soil and locally found vegetation species can also provide safe habitats for local insects, bees, and birds; in other words, it would provide wildlife habitat and biodiversity enhancement [54].…”

Plant Colonization of Green Roofs Is Affected by Composition of Established Native Plant Communities

“…These results suggest that green roof plant colonization does not depend on the amount of green space surrounding roofs. However, research on highly mobile insects suggests that the landscape surrounding a green roof is important in shaping green roof invertebrate communities (Braaker et al, 2017), which, in turn, serve as prey for birds (Partridge and Clark, 2018). In the current study, animal dispersed plant colonist species were abundant, suggesting that the role of the surrounding landscape on plant colonization could be related to landscape variables not measured.…”