Details

Autor(en) / Beteiligte

• Jedlicka, Julie A

Titel

Integrating avian conservation, community ecology, and insect pest management in California vineyards

Ort / Verlag

ProQuest Dissertations & Theses

Erscheinungsjahr

2011

Quelle

ProQuest Dissertations & Theses A&I

Beschreibungen/Notizen

• Because one out of every eight bird species is threatened with global extinction and 60% of the Earth's terrestrial surface is managed by humans, merging working landscapes with avian conservation could positively affect many birds. My overall research goal is to analyze avian conservation and biodiversity in agricultural systems. My approach is to consider ecosystem services provided by birds, active resource provisioning for birds, and the socio-economic and political motivations for grassroots conservation efforts. To begin, I synthesize important lessons from Latin American agroecosystems where most of the studies evaluating avian conservation in anthropogenic landscapes have been performed. Through this literature review, I develop and test hypotheses of how birds may respond to conservation practices in fragmented agricultural landscapes in California, USA. Since 1950, over 1,000,000 acres of California oak woodlands have been converted to agricultural and urban land. As oaks are removed, many cavity-nesting songbirds are left without nesting sites in a landscape increasingly composed of vineyards. By analyzing avian captures in mist nets, I test whether there is overlap in the composition of avian species found in California vineyards, adjacent gallery forests, and oak woodlands. I show that avian diversity in remnant riparian areas of vineyard landscapes is relatively high and retains two-thirds of the species found in oak woodland habitats. In addition, vineyards provide habitat to a different assemblage of avian species, those preferring semi-open habitat. Finally, I experimentally test whether establishing songbird nest boxes in California vineyards increased local densities of insectivorous birds and whether these birds provide growers with ecosystem services in the form of pest control. I compared the abundance of foraging birds, avian species richness, and removal rates of sentinel pests in treatments with and controls without songbird nest boxes. Insectivorous bird density nearly quadrupled, primarily because of a tenfold increase in Western Bluebird (Sialia mexicana) abundance. Removal rates of sentinel prey were 2.4 times higher in the nest box treatment than in the control. Consequently the presence of Western Bluebirds in vineyard nest boxes strengthened ecosystem services to winegrape growers, illustrating a benefit of agroecological conservation practices.