Vol. 49 No. 3, 2010
Foraging Guilds of Waterbirds Wintering in a Mediterranean Coastal Wetland
Hellenic Forest Service, 12 Minoas str., GR-19100 Megara, Attiki, Greece
Vasilios Liordos (2010)
The foraging behavior of the waterbird assemblage of a small
Mediterranean coastal wetland at Vourkari inlet, Saronikos Gulf,
Greece, was studied during the wintering season of 2007-2008. The
foraging habitat types and feeding techniques used by each individual
of 14 species were recorded during 30 sessions, each involving 4
observation points from which the entire wetland could be
scanned. Seven habitat types and 11 feeding techniques were used
by waterbirds during the study period. The waterbird assemblage
was classified into 5 foraging guilds: stalking ardeids (1 egret and 1
heron), shallow-water divers (1 cormorant and 1 grebe), shallow-water
generalists (2 ducks and 4 gulls), shallow-water plunge-divers (1
tern), and mudpeckers (3 small shorebirds). The low bidimensional
niche breadth of most species, except gulls, and the low niche overlap
among species of different guilds suggested a relatively high degree of
specialization within this waterbird assemblage. In contrast, the
overlap between species of the same guild was high, although variations
in the use of habitats and mainly feeding techniques did occur.
Intra-guild habitat partitioning was also observed, with diving and
gull species using different zones of shallow-water areas. The 2
main habitats, shallow waters and intertidal mudflats, were the most
important for waterbirds, with halophytic vegetation being important
only for Little Egrets Egretta garzetta.
The information provided herein is useful for a better understanding of
birds’ habitat requirements and the future management and conservation
of coastal wetlands.
Key words: Foraging habitat, Feeding techniques, Bidimensional niche, Community structure, Vourkari inlet.
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