Foraging ecology of wintering wading birds along the Gulf of Mexico coast

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Title: Foraging ecology of wintering wading birds along the Gulf of Mexico coast
Author: Sherry, Dawn Ann
Abstract: I studied flock composition , distribution and foraging ecology of wintering wading birds along the Gulf of Mexico coast . I focused on geographic variability in wintering wading bird assemblages , the processes that structured these assemblages and habitat use by wading birds . I found considerable variation among three sites , Aransas National Wildlife Refuge (ANWR ) , Texas ; Marsh Island Wildlife Refuge (MIWR ) , Louisiana ; and Chassahowitzka National Wildlife Refuge (CNWR ) , Florida . Species comprising wintering wading bird assemblages varied regionally . ANWR had the most species -rich assemblage , with eight species . MIWR had only six wading bird species . And CNWR had only three different species . Processes that structured wintering wading bird assemblages also varied regionally . In ANWR , Texas , the Random Fraction niche apportionment model (RF model ) best explained the empirical abundance data for ANWR . For abundance data from MIWR a good fit was obtained with the MacArthur Fraction (MF ) model and the Power Fraction (PF ) models . None of the models fully explained the CNWR abundance data . I also examined patterns of habitat partitioning among wintering wading birds at three different scales at two sites , Matagorda Island National Wildlife Refuge (MINWR ) and Laguna Atascosa National Wildlife Refuge (LANWR ) . At the macrohabitat level , wintering wading birds showed interspecific differences in macrohabitat use of both open water habitats and vegetated flats . At the mesohabitat level all species at MINWR used the category nearest the edge most often , alternatively , at LANWR wading birds were most often in the mesohabitat category of 8 .1 - 12 m . from the edge . In both locations wading birds partitioned habitat based on water depth . Finally , I found that Great Egrets and Snowy Egrets participated more often in flock foraging and derived more benefits from feeding in flocks than other species . Great Egrets feeding in flocks had a higher mean strike rate than those foraging alone , whereas Snowy Egrets had a higher success rate foraging in flocks than those foraging alone . In the case of the darkercolored species (e .g . , Great Blue Herons , etc . ) they either showed no difference in behaviors between birds foraging in flocks versus those foraging alone or they actually did worse when they foraged in flocks .
URI: http : / /hdl .handle .net /1969 .1 /4657
Date: 2007-04-25

Citation

Foraging ecology of wintering wading birds along the Gulf of Mexico coast. Available electronically from http : / /hdl .handle .net /1969 .1 /4657 .

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