Daily feeding site selection of cattle and sheep co-grazing a heterogeneous subtropical grassland Estanislao Martín Díaz Falú a,b,n , Miguel Ángel Brizuela b,c , María Silvia Cid b , Andrés Francisco Cibils d , María Gabriela Cendoya b , Diego Bendersky e a Institute of Animal Production in the Tropics and Subtropics, University of Hohenheim, Germany b Facultad de Ciencias Agrarias, Universidad Nacional de Mar del Plata, Argentina c CIC Buenos Aires, Argentina d Department of Animal and Range Sciences, New Mexico State University, USA e Instituto Nacional de Tecnología Agropecuaria, EEA Mercedes, Argentina article info Article history: Received 21 June 2013 Received in revised form 12 November 2013 Accepted 14 November 2013 Keywords: Foraging behavior Grazing distribution k-select analysis Grazing management Rangelands abstract Effective management of livestock grazing on heterogeneous subtropical grasslands requires understanding the relative role played by factors that determine spatial distribution patterns of animals. We conducted a 2 year study at a site in Corrientes, Argentina, to characterize seasonal patterns of feeding site selection of cattle and sheep co-grazing the same pastures. Livestock were fitted with GPS collars and monitored for 2 weeks in fall, winter, spring, and summer of two consecutive years beginning in 2009. Maps of vegetation units, topography, and facilities were included as layers in a GIS of our study site which, in addition to livestock location data, were used to analyze daily feeding site selection patterns of both livestock species. The k-select multivariate method used for this analysis suggested that 21% of the variation in daily feeding site selection of both cattle and sheep could be explained by vegetation-related variables. Lesser amounts of variation were explained by weather-related variables, topography, and distance to drinking water and shade. In general, cattle tended to select lower elevation sites dominated by taller grasses, whereas sheep tended to select higher elevation sites with steeper slopes dominated by short grasses. Both cattle and sheep appeared to adapt to year-to-year changes in vegetation and rainfall by adjusting their feeding site selection and either expanding or contracting the area explored while grazing in a day. Spatial overlap between species remained low throughout the study. Cattle and sheep appeared to exhibit complementary adaptive feeding strategies at this site. Subtropical grassland areas with heterogeneous vegetation cover could be utilized more efficiently with co-grazing of livestock species with contrasting body size and dietary habits. & 2014 Published by Elsevier B.V. 1. Introduction Understanding the relative role played by factors that determine spatial distribution patterns of domestic ungulates is critical for the sustainable management of grazed ecosystems. The extension and heterogeneity that characterize native grasslands allow ungulates to express their selection ability at several spatial and temporal scales, a process that usually results in uneven spatial dis- tribution of grazing (Parsons and Dumont, 2003; Laca, 2008). Since spatial patterns of herbivory affect critical aspects of vegetation structure and function (Hobbs, 1996; Marriot and Carrère, 1998; Adler et al., 2001; Cid et al., 2008), Contents lists available at ScienceDirect journal homepage: www.elsevier.com/locate/livsci Livestock Science 1871-1413/$ - see front matter & 2014 Published by Elsevier B.V. http://dx.doi.org/10.1016/j.livsci.2013.11.010 n Corresponding author at: University of Hohenheim, Institute of Animal Production in the Tropics and Subtropics, Fruwirthstraße 31, 70599 Stuttgart, Germany. Tel.: þ49 711 459 23641. E-mail address: diazfalu@gmail.com (E.M. Díaz Falú). Livestock Science 161 (2014) 147–157