Dissertation/Thesis Abstract

Waterbird and raptor communities in the Modulos de Apure region of the Venezuelan Llanos: An emphasis on temporal and multiscale waterbird-habitat relationships
by Baltzersen, Wendy J., Ph.D., State University of New York College of Environmental Science and Forestry, 2011, 276; 3494495
Abstract (Summary)

The Venezuelan Llanos is one of the world's remaining wetland wilderness regions wherein soil conditions and extreme flooding has limited agriculture and human density in the central depression. Within the central depression, the Modulos de Apure is considered a focal conservation area for waterbirds and raptors but population and habitat assessments are lacking. However, the highly seasonal and rural landscape also provided opportunities to broaden our understanding of spatial and temporal dynamics of waterbird-habitat relationships.

Community structure and baseline population for waterbirds and raptors were obtained from systematic surveys conducted in 2000–2002. Waterbirds were more abundant (20, 1095 individuals) and represented by more species (67 species) than raptors (25 species, 2858 individuals). The spatial distribution of these taxa revealed waterbird abundance was highest on private ranches, but raptor abundance near gallery forests. However, the most species rich and diverse raptor and waterbird communities were also highest in proximity to gallery forests. My findings validated the importance of private ranches for waterbirds, but identified gallery forest habitats as an important landscape component for avian communities overall.

I explored the temporal dynamics of wetland use by waterbird guilds during four distinct hydroperiods over two years. Open water cover was most commonly included models but typically accompanied by wetland or surrounding vegetation. All guilds exhibited temporal variability in models, wherein relationships for shorebirds, waders, and waterfowl were strongly associated with regional wetland availability. Annual variation in water level, hydroperiod, and timing of breeding also appeared to influence site use by waterbirds.

I identified relationships between waterbird guilds and landscape mosaics for varying spatial extents during the dry season in 2001. All guilds were related to at least one landscape component but all relationships were sensitive to landscape extent. Guild abundance was most strongly related to landscapes, wherein potential threshold responses were identified. Open water and convoluted perimeters of both wetland and forest patches were identified as important elements of the landscape for waterbirds in the Modulo Region.

Indexing (document details)
Advisor: Baldassarre, Guy A., Manno, Jack P.
Commitee: Bildstein, Keith L., Gibbs, James P., Quackenbush, Lindi J., Stehman, Stephen V.
School: State University of New York College of Environmental Science and Forestry
Department: Environmental & Forest Biology
School Location: United States -- New York
Source: DAI-B 73/05, Dissertation Abstracts International
Subjects: Wildlife Conservation, Wildlife Management
Keywords: Landscapes, Neotropics, Raptors, Waterbirds, Wetlands
Publication Number: 3494495
ISBN: 978-1-267-16467-4
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