Zoological Studies

Vol. 49 No. 3, 2010

Foraging Guilds of Waterbirds Wintering in a Mediterranean Coastal Wetland

Vasilios Liordos*

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.

*Correspondence: Tel: 30-22960-83651.  Fax: 30-22960-83652.  E-mail:liordos@yahoo.com