ABSTRACT: The Burrowing Owl (Athene cunicularia Molina 1782) has a wide distribution in Peru. In the present work, the feeding habits and dietary selectivity of A. cunicularia were studied in two contrasting geographical areas, the coastal area of Lomas de Yuta, Islay province and in the Andes, in the Chiguata district, Arequipa province, Peru. In both areas, six Classes, se r ven Orders, 13 families were identified, being the Insecta class the one with the highest representation with seven Coleoptera and one Hymenoptera families. Although no differences were detected between the frequency and biomass of prey, variations in the amplitude of the trophic niche were detected, being greater in the Andes (B = 4.52) than in the coast (B = 2.07). In addition, a differential dietary selectivity was recorded depending on the area, with a greater preference in the Sierra for Bothriuridae and Carabidae, while on the coast there was a greater preference for Bothriuridae, Tenebrionidae, Calosoma sp. and Carabidae.

RESUMEN: La lechucita de los arenales (Athene cunicularia Molina 1782) tiene amplia distribución en Perú. En este trabajo se estudian los hábitos alimenticios y selectividad dietaria de A. cunicularia en dos áreas geográficas contrastantes: la zona costera de Lomas de Yuta, provincia de Islay, y en ambiente de sierra, en el distrito de Chiguata, provincia de Arequipa, Perú. En ambas zonas se identificaron seis clases, siete órdenes y 13 familias. La clase Insecta es la de mayor representación con siete familias de Coleóptera y una de Hymenoptera. Si bien no se detectaron diferencias entre la frecuencia y biomasa de presas, sí se observaron variaciones en la amplitud de nicho trófico, la cual es mayor en sierra (B = 4,52) que en costa (B = 2,07). Además, se registró una selectividad dietaria diferencial dependiendo del área, con mayor preferencia en sierra por Bothriuridae y Carabidae, mientras que en costa se observó mayor preferencia por Bothriuridae, Tenebrionidae, Calosoma sp. y Carabidae.

ABSTRACT A paradigm in ornithology argues that in suboscine Passerines (suborder Tyranni) songs are genetically inherited and usually do not show evidence of vocal learning and individual or geographic variation. In this work, we evaluated the individual and geographic variation in the territorial songs of five populations of Scelorchilus rubecula, a suboscine bird endemic of the temperate forests of southern Argentina and Chile. Three complementary methods were used (1) sonograms cross-correlation, (2) coefficient of variation and (3) non-metric multi-dimensional scaling (MDS). The results suggest individually consistency in songs and vocal variation among individuals of S. rubecula. This high consistency of individual songs (66 - 91 %) in comparison with songs of other individuals of the same population (17 - 50 %) indicate that some variables (i.e., duration of phrase 1, FMA start phrase 1 and FMA end phrase 2) of S. rubecula territorial song can be used for individual identification. At geographical/population-level the MDS analysis did not show a clear structured pattern, distant geographic areas were grouped in the MDS arrangements.

RESUMEN Un paradigma en ornitología sostiene que en los Passeriformes subóscinos (suborden Tyranni) los cantos son heredados genéticamente y, generalmente, no muestran ninguna evidencia de aprendizaje vocal y variación individual o geográfica. En este trabajo se evalúa la variación individual y geográfica en las vocalizaciones territoriales de cinco poblaciones de Scelorchilus rubecula, un ave suboscina endémica de los bosques templados del sur de Argentina y Chile. Se utilizaron tres métodos complementarios (1) correlación cruzada de sonogramas, (2) coeficiente de variación y (3) ordenamiento multidimensional (MDS). Los resultados sugieren consistencia en las vocalizaciones a nivel individual y variación vocal entre individuos de S. rubecula. Esta alta consistencia de las vocalizaciones individuales (66 - 91 %) en relación con las vocalizaciones de otros individuos de la misma población (17 - 50 %), indican que algunas variables (i.e., duración frase 1, FMA inicio frase 1, FMA final frase 2) de la vocalización territorial de S. rubecula pueden ser utilizadas para la identificación individual, mientras que a nivel geográfico/poblacional no se obtuvo una clara estructuración, áreas geográficas distantes se agruparon en los arreglos MDS.

ABSTRACT Geranoaetus polyosoma (Quoy & Gaimard, 1824) is a diurnal raptor widely distributed in South America. Although the trophic ecology of this bird has been more studied in the southern extreme of its range, little information is available on its dietary response to prey supply in desert environments. In the present study, we report on the trophic ecology of G. polyosoma in a sub-urban desert zone in northern Chile, with the following objectives: (1) to quantitatively describe its diet and (2) to determine its dietary selectivity in response to prey supply in the study area. The diet of G. polyosoma consisted mainly of rodents (97.2%). A greater preference (p < 0.05) was observed for the following large prey items (> 19.5 g): two native rodent species, Phyllotis xanthopygus (Waterhouse, 1837) and Eligmodontia puerulus (Philippi, 1896); and two introduced rodent species: Rattus rattus (Linnaeus, 1769) and R. norvegicus (Berkenhout, 1769).