Habitat Characteristics Affecting Wading Bird Use of Geographically Isolated Wetlands in the U.S. Southeastern Coastal P
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GENERAL WETLAND SCIENCE
Habitat Characteristics Affecting Wading Bird Use of Geographically Isolated Wetlands in the U.S. Southeastern Coastal Plain Camille E. Herteux 1,2
&
Dale E. Gawlik 1 & Lora L. Smith 2
Received: 25 June 2019 / Accepted: 13 November 2019 # Society of Wetland Scientists 2019
Abstract Geographically isolated wetlands (GIWs) have been increasingly recognized for their importance in providing ecosystem services, including support of regional biodiversity. These wetlands serve as valuable foraging and breeding habitat for wetland-dependent species, including wading birds. In certain regions of the U.S. Southeastern Coastal Plain approximately two-thirds of GIWs are impacted by adjacent human land use. We quantified wading bird density in agricultural and natural GIWs to determine the factors influencing their use of these habitats. Using monthly transect surveys, we found that wetlandspecific variables, including prey abundance and size, wetland surface area, and dry-down rate, were better predictors of wading bird density than landscape level variables such as wetland density and distance to breeding colony. Bird density was highest in agricultural wetlands early in the hydroperiod, but as GIWs dried down, density dropped in agricultural wetlands and rose in natural wetlands. Collectively, these results suggest that wading birds in the Coastal Plain rely on a matrix of both agricultural and natural wetlands, and their use of wetlands varies temporally, peaking in late spring, to maximize prey availability. The seasonal process of receding water levels in GIWs and subsequent concentration of aquatic fauna provides important food resources for nesting wading birds. Keywords Wading birds . Habitat selection . Isolated wetlands . Agriculture . Foraging
Introduction Wading birds (orders Ciconiiformes and Pelecaniformes) are widespread and conspicuous apex predators in wetlands (Davis and Ogden 1994). To forage successfully, they require both suitable prey densities and shallow water (< 40 cm for most species; Powell 1987) that facilitates prey capture. These essential foraging conditions are often short-lived, causing birds to change foraging locations frequently and therefore Electronic supplementary material The online version of this article (https://doi.org/10.1007/s13157-019-01250-y) contains supplementary material, which is available to authorized users. * Camille E. Herteux [email protected] 1
Environmental Science Program, Florida Atlantic University, Boca Raton, Florida 33443, USA
2
Joseph W. Jones Ecological Research Center, Newton, Georgia 39870, USA
have large home ranges (Hafner et al. 1982; Erwin 1983). Due to their high position in aquatic food webs and considerable mobility, wading birds are important functional components in wetland ecosystems (Frederick and Ogden 2003). Because of their trophic status, they are also considered good indicators of wetland quality (Kushlan 1993; Frederick et al. 2009). Wetlands in much of the U.S. tend to be unevenly distributed across land
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