Foraging habitat selection of nesting Great Egrets (
Ardea alba
) and Snowy Egrets (
Egretta thula
) was
investigated within an estuary with extensive impounded salt marsh habitat. Using a geographic information system,
available habitat was partitioned into concentric bands at five, ten, and 15 km radius from nesting colonies to assess
the relative effects of habitat composition and distance on habitat selection. Snowy Egrets were more likely than
Great Egrets to depart colonies and travel to foraging sites in groups, but both species usually arrived at sites that
were occupied by other wading birds. Mean flight distances were 6.2 km (SE = 0.4, N = 28, range 1.8-10.7 km) for
Great Egrets and 4.7 km (SE = 0.48, N = 31, range 0.7-12.5 km) for Snowy Egrets. At the broadest spatial scale both
species used impounded (mostly salt marsh) and estuarine edge habitat more than expected based on availability
while avoiding unimpounded (mostly fresh water wetland) habitat. At more local scales habitat use matched availability.
Interpretation of habitat preference differed with the types of habitat that were included and the maximum
distance that habitat was considered available. These results illustrate that caution is needed when interpreting the
results of habitat preference studies when individuals are constrained in their choice of habitats, such as for central
place foragers