Abstract

D´HIRIART, Sofía; ORTIZ, Pablo E; GONZALEZ, F. Rodrigo  and  JAYAT, J. Pablo. Trophic ecology of the barn owl (Tyto furcata) in the Yungas of northwestern Argentina. Ecol. austral [online]. 2017, vol.27, n.3, pp.364-374. ISSN 1667-782X.

There is few information on the trophic habits of Tyto furcata in northwestern Argentina, and none in Yungas ecoregion. From pellets analyses, we characterized the diet of this raptor in six localities from Yungas of Argentina. We documented the diversity and composition of the prey-items and analyzed trophic parameters in the context of different degrees of natural cover transformation. The study includes a general characterization and a seasonal analysis. Rodents constituted 98% of the total preys and were the prey items which contributed the most to the diet in terms of biomass. The values for food niche breadth (FNB) and the standardized food niche breadth were higher in comparison with those observed in other areas of Argentina. We observed key seasonal changes in species composition in each locality. FNB was higher during the wet season and the trophic overlap among seasons was relatively high. The relationship between the degree of anthropic modification and trophic parameters was weak. Our results agree with those reported for South America, with a relatively broad spectrum of prey and a marked selectivity for cricetid rodents. Some localities exhibited a trend towards the reduction of FNB during the dry season, which might reflect the seasonal variation in the abundance of small mammals, with higher population sizes in the dry season. This would force the barn owl to adopt a more generalist diet in summer. In the studied localities, the proportion of land use does not seem to be relevant on the trophic parameters assessed, at least at this scale of analysis. Although our results constitute an important starting point for the study of the food niche of Tyto furcata in the Yungas, is evident the need for additional studies to elucidate many aspects related to the ecology of this raptor.

Keywords : Yungas ecoregion; Strigiformes; Diet; Small mammals; Food-niche breadth.