Residential irrigation as a driver of urban bird communities

Background/Question/Methods The demand for fresh water has largely outpaced supply both globally and locally with current water management policies unable to meet the needs of urban, agricultural, and industrial activities. Irrigation is one of the many anthropogenic uses of water and is arguably the most important maintenance factor in a landscape. This is particularly true in an arid climate, such as the Central Valley of California. Urban residents' decisions about the design and maintenance of their landscapes affect bird species richness. Published research indicates that these decisions are also affected by the residents' socioeconomic status. However, the driver of this relationship remains unknown. This paper uses data from the Fresno Bird Count, a citizen science organization, to test the hypothesis that neighborhood socioeconomic status influences residential irrigation regimes, which influences plant cover, in turn influencing bird diversity and abundance. A random sampling grid containing 460 points are used as locations for five minute point counts for the Fresno Bird Count (fresnobirds.org). Socioeconomic data has been obtained from the U.S. Census and irrigation regimes from the city of Fresno. Aerial imagery and ground sampling on point count locations are used for characterizing habitat.

Results/Conclusions Preliminary analysis of the first year of data (2008) supports this hypothesis and reveals a north/south gradient of bird diversity paralleling the socioeconomic gradient of Fresno. This paper will present results from a more comprehensive analysis of data including the spring 2009 bird census. Policies in the U.S. regarding the distribution and cost of water are changing in response to increased water demands, and the city of Fresno is about to undergo such a change. In 2013 a policy of metered water is scheduled to begin, which is predicted to increase water conservation by residents due to an increase in it overall cost. In addition to examining coupled socio-ecological drivers of urban diversity, this study will be the first part of a Before After Control Impact experiment taking advantage of the planned implementation of metering the cost of water use. The results can help guide the city in improving its management of urban habitat and biodiversity.