Native Landscaping in Urban Areas Can Help Native Birds

[Laurie Knight <>]

Synopsis at  http://www.sciencedaily.com/releases/2012/08/120822184134.htm

Article at

http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0043497

Linking Foraging Decisions to Residential Yard Bird Composition
        Susannah B. Lerman1¤*, Paige S. Warren2, Hilary Gan3,Eyal Shochat3,4

Urban bird communities have higher densities but lower diversity  
compared with wildlands. However, recent studies show that residential  
urban yards with native plantings have higher native bird diversity  
compared with yards with exotic vegetation. Here we tested whether  
landscape designs also affect bird foraging behavior. We estimated  
foraging decisions by measuring the giving-up densities (GUD; amount  
of food resources remaining when the final forager quits foraging on  
an artificial food patch, i.e seed trays) in residential yards in  
Phoenix, AZ, USA. We assessed how two yard designs (mesic: lush,  
exotic vegetation; xeric: drought-tolerant and native vegetation)  
differed in foraging costs. Further, we developed a statistical model  
to calculate GUDs for every species visiting the seed tray. Birds  
foraging in mesic yards depleted seed trays to a lower level (i.e. had  
lower GUDs) compared to birds foraging in xeric yards. After  
accounting for bird densities, the lower GUDs in mesic yards appeared  
largely driven by invasive and synanthropic species. Furthermore,  
behavioral responses of individual species were affected by yard  
design. Species visiting trays in both yard designs had lower GUDs in  
mesic yards. Differences in resource abundance (i.e., alternative  
resources more abundant and of higher quality in xeric yards)  
contributed to our results, while predation costs associated with  
foraging did not. By enhancing the GUD, a common method for assessing  
the costs associated with foraging, our statistical model provided  
insights into how individual species and bird densities influenced the  
GUD. These differences we found in foraging behavior were indicative  
of differences in habitat quality, and thus our study lends additional  
support for native landscapes to help reverse the loss of urban bird  
diversity.
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