Utility of Riparian Corridors to Fragmented Songbird Communities

What species: Anna's Hummingbird (Turdus migratorius, Bewick's Wren (Thryomanes bewickii, Black Phoebe (Sayornis nigricans, Blue-headed Vireo (Vireo solitarius, Bullocks Oriole (Icterus bullockii, Bushtit (Psaltriparus minimus, California Quail (Callipepla californica, California Towhee (Pipilo crissalis, Chicadee (Poecile rufescens, Chipping Sparrow (Spizella passerina, Downy Woodpecker (Picoides pubescens, House Finch (Carpodacus mexicanus, House Wren (Troglodytes aedon, Hutton's Vireo (Vireo huttoni, Lesser Goldfinch (Carduelis psaltria, Northern Flicker (Colaptes auratus, Nuttall's Woodpecker (Picoides nuttallii, Oak Titmouse (Baeolophus inornatus, Orange-crowned Warbler (Vermivora celata, Oregon Junco (Junco hyernalis, Pacific-slope Flycatcher (Empidonax difficilis, Pileated Woodpecker (Dryocopus pileatus, Spotted Towhee (Pipilo maculates, Violet-green Swallow (Tachycineta thalassina, Warbling Vireo (Vireo qilvus, Western Bluebird (Sialia mexicana, Western Kingbird (Tyrannus verticalis, White-breasted Nuthatch (Sitta carolinensis.

Where: Alexander and Sonoma Valleys in Sonoma County, CA.

Who: Katie Meiklejohn in association with Columbia University and the Wildlife Conservation Society.

When: April, 2006 – present

Why (threats): Human encroachment in the form of vineyard expansion has led to widespread habitat loss and fragmentation in northern California. This expansion threatens biodiversity, particularly species such as many songbirds that rely on continuous habitat for survival. Agricultural lands often function as barriers to dispersal, preventing migrations, cutting-off important food or habitat sources, and inhibiting gene flow between populations. Conservation biologists have proposed the use of habitat corridors as a means of improving connectivity in highly fragmented landscapes or as important areas of breeding habitat for other species, but more data are needed before conclusions can be drawn about the efficacy of corridors at improving population viability. The highly fragmented oak woodland-vineyard landscape of northern California offers a unique opportunity to assess the utility of habitat corridors to a variety of passerine species.

Current scientific or conservation problem this project addresses: The purpose of this study is to assess the value of riparian corridors to breeding songbird populations in order to add to existing scientific theory on the ability of habitat corridors to combat the negative effects of landscape fragmentation. These data will provide local and regional managers and farmers with information pertinent to the design of functional agro-ecosystems.

Current Goals: This project is currently in the data analysis stage. I am working in collaboration with statisticians from the Wildlife Conservation Society (WCS), and hope to publish my results next year.

Next Steps: Conservation corridors have great potential to improve landscape connectivity for a range of species, but different organisms will use corridors in different ways. Understanding these differences is critical to the design of effective corridors. My research is based on some existing work by Jodi Hilty of the WCS North America Program who collected presence-absence data for carnivores and songbirds in Sonoma County during her dissertation research. In collaboration with Jodi I hope to combine my results with this presence-absence data to assess the differences that might exist between carnivore and passerine communities within these corridors.

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