Feeding Biology of Pectoral Sandpiper Calidris Melanotos (Birds: Scolopacidae) In the Floodplain of the Paraná River, Argentina

This study focuses upon the nourishing biology of the Pectoral Sandpiper at the floodplain of the Paraná river during  spring and summer. Trophic spectrum, feeding selectivity and efficiency, extent of the trophic niche, circadian rhythm of feeding activity, size of preys and habitat preference were evaluated. Twenty eight stomachs were analyzed Containing twenty-seven taxonomic entities: 12 were vegetal 15 animal. The highest index’s values of relative importance were for seeds and coleoptera; showing this a generalist diet. The amplitude of the trophic niche remined constant along the studied periodFeeding was more active during early morning hours. The more frequent prey size were between 1.5 and 5 mm .The habitat preference index was registered only for the beach (Pi=0.7). This work constitutes the first contribution to knowledge of this species feeding ecology in this region.Fil: Bagnarol, Mónica. Universidad Nacional del Litoral. Facultad de Humanidades y Ciencias; ArgentinaFil: Beltzer, Adolfo Hector. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto Nacional de Limnología. Universidad Nacional del Litoral. Instituto Nacional de Limnología; ArgentinaFil: Quiroga, Martin Anibal. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto Nacional de Limnología. Universidad Nacional del Litoral. Instituto Nacional de Limnología; ArgentinaFil: Ducommun, Maria de la Paz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto Nacional de Limnología. Universidad Nacional del Litoral. Instituto Nacional de Limnología; ArgentinaFil: Ronchi Virgolini, Ana Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto Nacional de Limnología. Universidad Nacional del Litoral. Instituto Nacional de Limnología; Argentin

Diet of Cocoi Heron (Ardea cocoi) in the Flood Valley of the Paraná River

We analysed the feeding ecology of Ardea cocoi based on twenty nine individuals captured on the Carabajal island (Santa Fe, 31º39’S, 60º42’W), determining the minimum sample, index of relative importance (IRI), size of prey, feeding efficiency, dietary selectivity, amplitude of the trophic niche, standardization, circadian rhythm of feeding activity and habitat preference. The trophic spectrum was made up of 17 taxonomic entities, mainly fishes (IRI = 16,000), followed by mammals and amphibians (IRI = 8,000). The highest percentage of prey size was found in the interval 151 -> 200 mm. The amplitude of the trophic niche ranged between 1.98 and 4.21, and the feeding efficiency between 89.9% and 99.9%. In relation to dietary selectivity, the correlation between abundance of prey in stomachs and abundance of prey in the study area yielded no significant results (rs = 0.078, P > 0.001). The rhythm of feeding activity responded to the bell-shaped model. Aquatic vegetation was the unit of vegetation and environment selected more frequently.Fil: Ducommun, Maria de la Paz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto Nacional de Limnología. Universidad Nacional del Litoral. Instituto Nacional de Limnología; ArgentinaFil: Beltzer, Adolfo Hector. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto Nacional de Limnología. Universidad Nacional del Litoral. Instituto Nacional de Limnología; ArgentinaFil: Ronchi Virgolini, Ana Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto Nacional de Limnología. Universidad Nacional del Litoral. Instituto Nacional de Limnología; ArgentinaFil: Quiroga, Martin Anibal. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto Nacional de Limnología. Universidad Nacional del Litoral. Instituto Nacional de Limnología; Argentin