Green roof biodiversity in design: Influence of local and contextual attributes on bird usage

This purpose of this research is to identify how species of birds use urban green roofs in Iowa with the intent to eventually develop a set of guidelines for optimizing habitat on green roofs. Ten green roofs were observed for bird usage five times each between May to August, 2013 for a total of fifty observations. Birds were identified by species and their behavior was recorded during the duration of the observations. Data shows that birds use green roofs for a number of uses including foraging and gathering nest material. Bird diversity data was then compared with both green roof design and contextual attributes to define potential relationships. Regression analyses found that green roofs with areas greater than 2000 meters squared had significantly higher abundances of birds than smaller roofs. Contextually, green roofs with no standing water within 800 m also had significantly greater bird abundances. These two relationships are the start to establishing a set of guidelines that allow designers implement projects with a vested interest in bird diversity and with additional research additional guidelines can be developed