Resumen

OLGUIN, Pamela Fernanda et al. Feeding Biology of Syrigma sibilatrix (Birds: Ardeidae) in a wetland of the Middle Parana River, Argentina. Cuadernos de Investigación UNED [online]. 2017, vol.9, n.1, pp.91-96. ISSN 1659-4266.

The whistling heron (Syrigma sibilatrix) is a neotropical species that inhabits aquatic environments, rural areas and groves. We studied the diet of 19 birds in Carabajal Island (31°39´S, 60°42´W) from 1999 to 2003. The trophic spectrum was composed of 14 taxonomic units of animal taxa. Trophic diversity ranged between 0.23 and 2.15. Index of relative importance was of 10 780 for insects, 1 800 for arachnids and crustaceans, and 1 750 for vertebrates. Most of the prey were represented by individuals included in the 0-20 mm (45%) and 21-40 mm (35%) size intervals. Trophic niche breadth was of 1.98 in spring, 2.34 in summer, 2.21 in autumn, and 1.99 in winter; standardized values were of 0.075 in spring, 0.10 in summer, 0.09 in autumn, and 0.076 in winter. Feeding efficiency was 96.01% in spring, 98.3% in summer, 89.9% in autumn and 92.34% in winter. No evidence was found of food selectivity. The highest percentage of site fidelity (69%) corresponded to the grassland environment. In the floodplain of the Middle Parana River, S. sibilatrix primarily feeds on insects from grasslands.

Palabras clave : Feeding ecology; waterbirds; floodplain.

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