Ecología alimentaria de dos especies simpátricas del género Basileuterus en el noreste de Argentina

we studied the feeding ecology of two species of sympatric warblers, basileuterus leucoblepharus and basileuterus culicivorus, in the province of chaco, argentina, by analyzing their diet, foraging techniques and vertical distribution. sampling was conducted between december 2001 and september 2002 in the riparian forest of the paraná river floodplain. basileuterus leucoblepharus captured their prey mainly gleaning on the ground and in the herbaceous layer, and rarely over 1 m high. basileuterus culicivorus, on the contrary, captured prey in the undercanopy and shrub strata, mainly between 1.5-2 m high, using several foraging techniques (mainly reach-out, reach-up and hang-sideways). we recorded 9 prey items for basileuterus leucoblepharus and 12 for basileuterus culicivorus. stomachs of basileuterus leucoblepharus showed a numerical and volumetric predominance of curculionidae, followed in importance by other unidentified coleoptera. in basileuterus culicivorus, bruchidae and curculionidae were numerically important, while lepidoptera was volumetrically important. we found some diet overlap in these species, although their coexistence would be possible by their differences in the use of foraging techniques and in the vertical distribution within the riparian forest.