Foraging Habitat Selection of Glossy Ibis (Plegadis falcinellus) on an Australian Temporary Wetland

• Published in: Waterbirds (De Leon Springs, Fla.) Vol. 38; no. 4; pp. 364 - 372
• Main Authors: Taylor, Iain R, Taylor, Sarah G
• Format: Journal Article
• Language: English
• Published: Waterbirds Society 01.12.2015
• Subjects: cattle; Coleoptera; diet; drying; Eleocharis; Elymus repens subsp. repens; floodplains; foraging; grazing; habitat preferences; habitats; Hemiptera; herbivores; irrigated farming; macroinvertebrates; Paspalum distichum; Paspalum scrobiculatum; Plegadis falcinellus; population; rivers; roosting behavior; stocking rate; summer; swamps; Typha; wet season; New South Wales
• ISSN: 1524-4695; 1938-5390
• DOI: 10.1675/063.038.0413

Glossy Ibis (Plegadis falcinellus) populations have declined over much of their global range over the past 30 years and in Australia numbers fell by almost 40% between 1977–1981 and 1998–2002. In Australia, loss of wetland area and quality in relation to river regulation for irrigated agriculture are the main suggested causes. The species' diet has been quantified in many areas, but there have been no detailed studies of its foraging habitat requirements upon which to base conservation measures. This study quantified foraging habitat selection at Fivebough Swamp, New South Wales, an internationally important feeding and roosting site for non-breeding Glossy Ibis. Typical of many floodplain wetlands in southeastern Australia, Fivebough Swamp is temporary, flooding during the wet season and drying during the hot summer. Glossy Ibis showed a strong preference for feeding in areas of water couch grass (Paspalum distichum) less than 10 cm tall interspersed among open water, and avoidance of areas dominated by bulrush (Typha spp.), common spike rush (Eleocharis acuta) and open non-vegetated water. Water couch grass supported significantly higher densities of aquatic macroinvertebrate prey for Glossy Ibis than did the other habitats, including Gastrodpoda, Hemiptera and Coleoptera. Water couch grass can form dense contiguous mats of up to 50 cm in height above water level, which would be too high and dense for Glossy Ibis to probe through. In the absence of natural herbivores, livestock grazing by cattle (Bos taurus) at low stocking rates can be used to suppress this growth and maintain suitable conditions for Glossy Ibis.