Wading birds have been observed foraging in agricultural wetlands worldwide where natural wetlands have become lost, degraded, or seasonally dry, yet the ability of wading birds to satisfy daily energy requirements in agricultural wetlands has been little studied. The ability to meet daily energy requirements for Little Blue Herons (Egretta caerulea) and Great Egrets (Ardea alba) foraging in flooded rice and fallow fields of the Everglades Agricultural Area (EAA) was evaluated during April-June 2008 and 2009. Focal samples were used to measure capture rates (captures/min), identify prey and estimate captured prey size, and calculate energy budgets for both species. Within flooded fields prey density was measured and foraging sites and random locations were compared. Habitat variables did not differ between foraging sites and random locations. Vegetation cover and prey abundance increased in rice fields over time and were greater in rice than fallow fields. Small prey, dominated by fish, were captured by both species and corresponded to prey sampled. Most wading birds in June were observed in newly flooded fallow fields despite lower prey densities. Little Blue Herons met daily energy requirements for both years; but Great Egrets did not, likely due to predominantly small prey, increasing vegetative cover in rice fields, and lower prey densities in newly flooded fallow fields. Although Great Egrets did not meet daily caloric requirements, the EAA may still function as an important transitional habitat at a time when foraging resources in the region are limited.
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1 September 2012
Quality of Flooded Rice and Fallow Fields as Foraging Habitat for Little Blue Herons and Great Egrets in the Everglades Agricultural Area, USA
Grant C. Sizemore,
Martin B. Main
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Waterbirds
Vol. 35 • No. 3
September 2012
Vol. 35 • No. 3
September 2012
agricultural wetland
Ciconiiformes
Great Egret
little blue heron
rice