Type of Document Master's Thesis Author Gray, Jacob M URN etd-04272010-212919 Title Habitat Use, Movements, and Spring Migration Chronology and Corridors of Female Gadwalls that Winter along the Louisiana Gulf Coast Degree Master of Science (M.S.) Department Renewable Natural Resources Advisory Committee
Advisor Name Title Afton, Alan Committee Chair Chamberlain, Michael Committee Member Geaghan, James Committee Member Mitchell, Mark Committee Member Keywords
- coastal marsh
- Gulf Coast Chenier Plain
- wintering waterfowl
- habitat use
- satellite telemetry
Date of Defense 2009-12-17 Availability unrestricted AbstractThe Louisiana Gulf Coast is an important wintering area for North American gadwall (Anas strepera). Conservation of winter habitat is a top priority of the Gulf Coast Joint Venture. Quantitative estimates of habitat use by wintering gadwall would help improve energetic demand models and subsequent estimates of habitat requirements.
I used satellite telemetry (PTTs) to estimate winter habitat and refuge uses, spring migration chronology and corridors, as well as inter- and intra-regional winter movements of females. I used a split-plot MANOVA to evaluate the effects of individual females, female age, winter, hunt periods within winter, time of day, and all possible interactions among these explanatory variables on habitat use. I used a mixed model ANOVA to evaluate the effects of individual females, female age, winter, hunt periods within winter, time of day, and all possible interactions of these explanatory variables on refuge use. I used mixed models to evaluate the effects of hunt periods within winter, refuge use, winter, individual female, female age, and body condition at time of capture on intra-regional movements. Finally, I used a MANOVA to evaluate the effects of female age, spring of tracking, and body condition at time of capture on several spring migration parameters.
I found that habitat use in winter 2007-08 was dominated by intermediate marsh, whereas habitat use during winter 2008-09 showed an increased dependence on freshwater marsh (P = 0.0001). Use of non-hunted refuges by adult females was greater when hunting season was open than when closed (P = 0.0061).
I found no significant relationships among the explanatory variables and intra-regional movements (all Ps > 0.09). Peak migratory departure from the Louisiana Gulf Coast Chenier Plain occurred during late-March to early-April. HY females traveled a greater total migratory distance, spent more days migrating, used more stopovers, and arrived at inferred breeding locations later than did AHY females (all Ps ≤ 0.061).
My results suggest that intermediate marsh is important for wintering gadwall; however, freshwater marsh may become important after tidal surge events. Finally, my migration data provides habitat managers with quantitative information to consider when implementing conservation programs and management practices.
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