Avian response to green roofs in urban landscapes in the Midwestern USA

Abstract

ABSTRACT Green roofs present an opportunity to provide large areas of vegetation that could serve as bird habitat in urban areas. Point‐count surveys at 12 green‐roof study locations in the midwestern United States were conducted during the bird breeding season in 2010 and 2011. At each green roof location, birds were surveyed on building rooftops and at ground level around (<200 m) each building. Data collection resulted in 771 sampling periods during which 2,973 species detections (1,315 for native songbirds) were recorded. We estimated occupancy probabilities for birds with single‐ and multi‐species occupancy models, which accounted for detection and allowed for community‐level summaries such as species richness. Twenty‐six noninvasive, native bird species were detected on the roofs, and the estimated mean richness of native songbird and woodpecker species for each green roof was 10–21. Most species (approx. 90%) observed on green roofs also were observed in surrounding landscapes, and species richness estimates and species‐specific occupancy probabilities were typically lower for green roofs than for surrounding landscapes. Our results indicate that green roofs may contribute to habitat for a subset of birds already occurring in urbanized landscapes. Although surrounding areas likely provide greater bird habitat than vegetation on green roofs, several native songbird, woodpecker, and waterfowl species use green roofs in urban landscapes; hence, green roofs have potential to contribute to bird habitat in urban areas and may help mitigate negative effects of urbanization on birds. © 2015 The Wildlife Society.

Keywords

• bird communities
• bird conservation
• green buildings
• green space
• occupancy model
• urban ecology