Title page for ETD etd-04142010-140721


Type of Document Master's Thesis
Author Villani, Rachel K
URN etd-04142010-140721
Title Multi-Scale Habitat Associations of Shorebirds During Spring Migration in Southwestern Louisiana Rice Fields
Degree Master of Science (M.S.)
Department Renewable Natural Resources
Advisory Committee
Advisor Name Title
King, Sammy L Committee Chair
Kaller, Michael D Committee Member
Stouffer, Philip C Committee Member
Keywords
  • shorebirds
  • rice fields
  • landscape ecology
  • Louisiana
  • multi-scale
Date of Defense 2010-02-23
Availability unrestricted
Abstract
Rice is the most common wetland crop in the world, and important for waterbirds and shorebirds worldwide, including the United States. In Louisiana, shorebirds use rice fields during spring migration, and are an important for foraging and refueling during migration. However, competing land uses and restoration projects may reduce the availability of rice fields, and impact the landscape that shorebirds use during migration. To determine how shorebirds use the landscape, I evaluated local and landscape factors affecting shorebird use of rice fields during spring migration in southwestern Louisiana. Using five habitat suitability zones (HSZs) based on rice density and canopy cover, I performed stratified random surveys at rice fields within each of the 5 HSZs. I surveyed 94 fields in 2008 and 85 fields in 2009. I quantified all habitat types within 3 km of each field, recorded habitat conditions during each visit, and recorded all shorebirds observed. Mixed modeling analyses indicated that shorebird density was primarily influenced by local field conditions: flooding extent (p<00001), the percent of the field perimeter bordered by trees (p=0.0075), surveyed rice field area (p<0.0001), and rice height (p<0.0001). Shorebirds responded positively to flooding extent, and negatively to tree border, field area, and rice height. Overall shorebird density was not influenced by any landscape variables at any scale (1, 1.5, 2, 2.5, or 3 km). The percent of non-rice crop (p=0.0437) and fallow land (p=0.0400) immediately adjacent to surveyed fields was a positive influence on density of the seven most common species, and HSZ was a positive influence on shorebird habitat use for 3 of the most common species or species groupings: Dowitchers (2 spp), Peeps (3 spp), and Yellowlegs (2 spp). These species comprised > 50 % of all birds observed, indicating the importance of HSZ for individual species. Rice density was significantly higher in HSZ4 and HSZ5, and the percent of forest (an alternate measurement of canopy cover) was significantly lower in HSZs 4 and 5. These results support the validity of the habitat suitability model. By maintaining rice production in the higher HSZs, suitable local habitat conditions would be provided for shorebirds.
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