Summer feeding ecology of Great Pampa-finches, Embernagra platensis at Laguna de Guaminí, Buenos Aires, Argentina

Abstract

The aim of this study was to assemble data on the summer feeding ecology of the Great Pampa-finch, Embernagra platensis at the Laguna de Guaminí, Buenos Aires, Argentina, and to explore the differences related to the dietary patterns for each sex between winter and summer when possible. The stomach contents of 43 birds were analyzed. The animal fraction was composed of Hymenoptera (45.1%), Coleoptera (32.4%), Lepidoptera (6.0%), Araneae (5%) and Orthoptera (3.2%). The application of the index of relative importance (IRI) resulted in 1490.4 for Coleoptera, 428.5 for Hymenoptera and 162.5 for Lepidoptera caterpillars. The vegetal fraction consisted of Triticum aestivum (26.9%), Cyperaceous (25%), Poaceae (Gramineae) (19.3%) and Panicum sp. (11.2%). The IRI values were 893.8 for Triticum aestivum, 174.5 for Gramineae, 126.5 for Panicum sp. and 112.8 for Scirpus sp. The food niche width was 0.33 for both sexes; the diversity index resulted in 1.06 for females and 1.33 for males and specific diversity ranged from 1.87 to 2.84. A canonical component analysis (CCA) was performed on environmental and morphometric variables, and a Monte Carlo test confirmed the canonical correlations. A t-test showed that some birds harmonized with a logarithmic model and some with a geometric curve. During the summer, Embernagra platensis ingests Hymenoptera and Coleoptera more often than seeds, suggesting that two biological mechanisms could be taking place in this bird.

Diversity and Habitat Distribution of Birds in Coastal Marshes and Comparisons with Surrounding Upland Habitats in Southeastern South America

“…A factor contributing to partial migration may be the marked decrease in arthropod abundance during winter, as arthropods are an important food resource for most birds (furnarids, tyranids, and icterids) in SESA coastal marshes (Canepuccia et al 2009). Arthropods are also a major resource for emberizid species such as great Pampa-finch (Ferman and Montalti 2010;Montalti et al 2005). Seeds are not important food resources for coastal marsh birds, but some natural (i.e., burrowing crab bioturbation; Cardoni et al 2007) and/or anthropogenic disturbances (i.e., sewage discharge; Cardoni et al 2011) Estuaries and Coasts eating birds (Cardoni et al 2007(Cardoni et al , 2011.…”

<b>Dieta e conteúdo calórico de aves atropeladas na região central do estado do Paraná, Brasil</b><br>DOI:10.5007/2175-7925.2011v24n4p153

“…As cinco espécies aqui consideradas insetívoro/ frugívoras revelaram tendência oposta à esperada na proporção quantitativa dos itens alimentares, pois foi constatada para as mesmas uma dieta frugívoro/ insetívora. Esta constatação pode ser exclusivamente devido ao baixo n (1) de cada uma dessas espécies, pois a dieta dessas espécies pode variar sazonalmente (LÓPEZ-CALLEJA, 1995;PIRATELLI;PEREIRA, 2002;GOMES et al, 2008;FERMAN;MONTALTI, 2010). No entanto, o fato de serem espécies de borda de fl oresta ou de hábitat aberto pode ser determinante para que a alteração da paisagem, causada pela fragmentação do hábitat e substituição de áreas naturais por agropastoris, juntamente com o impacto da rodovia estejam afetando a disponibilidade de alimento para as mesmas.…”

“…Embernagra platensis foi a espécie pertencente ao grupo dos insetívoro/frugívoros com a dieta mais diversifi cada e com mais itens diferentes ingeridos. Destaca-se a ingestão de aranhas por esta espécie, que sugere que esta ave pode alimentar-se cavando o chão, removendo folhas, cascas de árvore e superfícies de solo explorado (FERMAN;MONTALTI, 2010).…”