Consumption of aquatic plants is rare among cervids, despite the common occurrence of this form of vegetation. However, the paucity of literature reporting on this feeding behaviour suggests that Na (but also other minerals), protein, and the ubiquitous availability of aquatic vegetation may play a role in its consumption. We present results quantifying those factors that regulate the consumption of aquatic plants in the Iberian red deer. We focussed our study primarily on two questions: (i) what nutritional values are red deer seeking in the aquatic plants?; and (ii) why do red deer primarily use aquatic plants during the summer? A comparison of the seasonal variations in Na content between terrestrial vs. aquatic vegetation did not fully support the hypothesis that aquatic plants are being consumed more in summer because of any seasonal variation in Na availability. The Na content in the aquatic vegetation was adequate all the year-round; whereas, the Na content in the terrestrial vegetation was consistently deficient. However, a greater summer content of essential minerals and protein in the aquatic vegetation may be the cause for their consumption exclusively during the summer. We suggest that seasonal variations in the consumption of aquatic vegetation by cervids is primarily driven by temporal variations in the nutrient content, combined with seasonal variations in the physiological demands for these nutrients.

Centre for African Ecology School of Animal Plant and Environmental Sciences University of the Witwatersrand Private Bag 3 Wits 2050 South Africa

Departamento de Ciencia y Tecnología Agroforestal y Genética Universidad de Castilla La Mancha 02071 Albacete Spain

Department of Animal Science and Food Processing Faculty of Tropical AgriSciences Czech University of Life Sciences Kamýcka 129 165 21 Prague 6 Suchdol Czech Republic

Laboratorio de Ciencia e Ingeniería de Materiales 02071 Albacete Spain

References provided by Crossref.org

Evaluation of factors inducing variability of faecal nutrients in captive red deer under variable demands

Avoiding toxic levels of essential minerals: a forgotten factor in deer diet preferences