Analía Andrade

Diet of the Burrowing Owl (Athene cunicularia) and its seasonal variation in Patagonian steppes: implications for biodiversity assessments in the Somuncurá Plateau Protected Area, Argentina

A wide literature exists on the food habits of the Burrowing Owl (Athene cunicularia) in South America. However, this information is scarce for the arid lands of Argentina. Owls diet composition in the Somuncurá Plateau and its seasonal variations were estimated. The Somuncurá landscape is a volcanic plateau conformed by superimposed layers of basalt flows. The climate is arid and cold and the vegetation is characterized by a grassy steppe of the Patagonian Phytogeographical Province. Pellets were collected during late spring and late summer around two lagoons from upper elevations (41°25′35″S, 66°57′27″W, 1412 m a.s.l.). These were measured, dissected and prey were identified and quantified. Sample richness, biomass and food-niche breadth were calculated as dietary parameters. Small mammals availability was estimated by trapping. The Burrowing Owl showed a generalist diet, including a wide variety of prey from invertebrates to vertebrates. Coleopterans were dominant in the spring diet, while rodents and arachnids became important in the late summer diet. The high species richness detected in this study through the analysis of raptor pellets is valuable for biodiversity assessments of unexplored areas such as Somuncurá.

Mammalia, Chiroptera, Molossidae, Tadarida brasiliensis I. Geoffroy, 1824: distribution extension

Tadarida brasiliensis is one of the most widely distributed mammalian species in America. We report the southernmost continental record for this species in Rada Tilly, province of Chubut, Argentina, extending its range ca. 390 km to the south.

Mammalia, Rodentia, Sigmodontinae, Akodon molinae Contreras, 1968: new locality records and filling gaps

Akodon molinae Contreras, 1968 is a large (holotype: 42.5 g), diurnal species with long and hispid fur, the dorsum is dark grey and the belly is whitish. The tail is shorter (holotype: 78 mm) than head and body (holotype: 108 mm), black dorsally and white in its centrally proximal third. The skull is large and strong, the zygomatic plate is wide and its edge is slightly convex and directed obliquely backwards and down (type description, Contreras 1968). The mandible has a short and robust coronoid process and an anteromedian flexus/flexid on the first upper and lower molars respectively, like other species in the genus Akodon. Cranial and dental remains of A. molinae are shown in Figure 1. The holotype was collected in vivero del Ministerio de Asuntos Agrarios, Laguna Chasicó, Buenos Aires province, Argentina, in grasslands near water bodies (Contreras 1968). Near the Atlantic coast, it lives in shrub steppes and halophilic plant communities (Daciuk 1974). Its distribution in northern Patagonia was associated with the Monte Phytogeographical Province (Pardiñas et al. 2003).

Comments on the status of Calomys callosus (Rengger) and new data on the distribution of mammals in the northwest Corrientes province (Argentina)

From cytogenetic and morphologic data, correspondence between Calomys callosus and C. callidus is discussed. The karyotypes described here for specimens of C. callosus from the province of Corrientes are almost identical with those described by other authors for specimens from the province of Entre Rios (ascribed to C. callidus ). Known data restrict the geographic range of Calomys callosus to the neighbourhood of the flood valley of the Paraguay River and the Argentine Mesopotamia. Furthermore, new distributional records of 16 species of small mammals (Marsupialia, Chiroptera, Rodentia) are presented from two localities in the northwest of the province of Corrientes: El Sombrero (27o 70’S - 58o 58’ W), department of Empedrado, and El Ponton (27o 56’S - 58o 45’ W), department of San Luis del Palmar. At both localities bone remains, mainly hemimandibles and cranial fragments, were recovered from Barn Owl pellets. The samples are largely dominated by Holochilus sp. , with low frequencies of Akodon cf. A. azarae , Akodon montensis , Calomys callosus , Gracilinanus agilis , Necromys temchuki , Oligoryzomys sp. cf. O. flavescens - O. microtis , Oligoryzomys nigripes , Scapteromys aquaticus and Oxymycterus rufus .