The Enhanced Vegetation Index (EVI) as a proxy for diet quality and composition in a mountain ungulate

In recent years, the use of satellite-derived vegetation indices has become a powerful tool to collect information on vegetation dynamics in a broad range of ecosystems worldwide. However, the utility of these indices as indicators of the diet composition and quality of herbivore mammals has not yet been established. This work focuses on exploring such relationships analysing four years of records of monthly Enhanced Vegetation Index (EVI, a MOD13 satellite-derived index) and diet composition and quality of two populations of chamois (Rupicapra pyrenaica pyrenaica) in the Eastern Pyrenees (Spain). Our results revealed that 68.4% and 53.3% of diet composition and quality of chamois can be explained by EVI values in the green-up season (spring) and green senescence (winter season), respectively. In both periods, EVI was related mainly to diets low in fibre (cellulose, hemicellulose and lignin) and heather (Calluna vulgaris) and high in nitrogen due to the consumption of Festuca, Forbs and Trifolium. During the summer season however, the EVI was not significantly related to diet components of chamois. A significant inter-year variability in the diets of the chamois was also observed. To conclude, remote sensing is appropriate to assess temporal variations in dietary components of mountain ungulates, and could be used as a component of monitoring large herbivore populations in management programmes.

A. Gálvez-Cerón was supported by an Erasmus Mundus programme from the European Commission, N. Fernández by the Excellence Programme of Junta de Andalucía (RNM-6685), and E. Serrano by the postdoctoral programme (SFRH/BPD/96637/2013) of the Fundação para a Ciência ea Tecnologia, Portugal. This study was partly funded by the CGL2009-11631 research project of the Spanish MICINN, the National Foundation for Science and Technology, through CESAM: UID/AMB/50017/2013, and the scientific programme “Approche Intégrée de la Démographie des Populations d’Isard” sponsored by the ONCFS and the SEFaS.