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1 October 2011 Dynamic Habitat Selection by Two Wading Bird Species with Divergent Foraging Strategies in a Seasonally Fluctuating Wetland
James M. Beerens, Dale E. Gawlik, Garth Herring, Mark I. Cook
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Abstract

Seasonal and annual variation in food availability during the breeding season plays an influential role in the population dynamics of many avian species. In highly dynamic ecosystems like wetlands, finding and exploiting food resources requires a flexible behavioral response that may produce different population trends that vary with a species' foraging strategy. We quantified dynamic foraging-habitat selection by breeding and radiotagged White Ibises (Eudocimus albus) and Great Egrets (Ardea alba) in the Florida Everglades, where fluctuation in food resources is pronounced because of seasonal drying and flooding. The White Ibis is a tactile “searcher” species in population decline that specializes on highly concentrated prey, whereas the Great Egret, in a growing population, is a visual “exploiter” species that requires lower prey concentrations. In a year with high food availability, resource-selection functions for both species included variables that changed over multiannual time scales and were associated with increased prey production. In a year with low food availability, resource-selection functions included short-term variables that concentrated prey (e.g., water recession rates and reversals in drying pattern), which suggests an adaptive response to poor foraging conditions. In both years, the White Ibis was more restricted in its use of habitats than the Great Egret. Real-time species—habitat suitability models were developed to monitor and assess the daily availability and quality of spatially explicit habitat resources for both species. The models, evaluated through hindcasting using independent observations, demonstrated that habitat use of the more specialized White Ibis was more accurately predicted than that of the more generalist Great Egret.

© 2011 by The American Ornithologists' Union. All rights reserved. Please direct all requests for permission to photocopy or reproduce article content through the University of California Press's Rights and Permissions website, http://www.ucpressjournals.com/reprintInfo.asp.
James M. Beerens, Dale E. Gawlik, Garth Herring, and Mark I. Cook "Dynamic Habitat Selection by Two Wading Bird Species with Divergent Foraging Strategies in a Seasonally Fluctuating Wetland," The Auk 128(4), 651-662, (1 October 2011). https://doi.org/10.1525/auk.2011.10165
Received: 6 July 2010; Accepted: 2 July 2011; Published: 1 October 2011
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KEYWORDS
Ardea alba
Eudocimus albus
Florida Everglades
foraging strategies
habitat selection
prey availability
resource selection functions
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