REGIONAL VARIATION IN MINERAL CONTENTS OF PLANTS AND ITS SIGNIFICANCE FOR MIGRATION BY ARCTIC REINDEER AND CARIBOU
Ten minerals, 6 macro (Na, K, Ca, P, Mg, Cl) and 4 trace elements (Co, Cu, Mo, Mn), were analysed in 13 forage plants of reindeer and caribou (Rangifer tarandus) to compare differences between coastal and interior areas. Samples were collected in northern Norway (coastal and interior regions), southern Norway (interior), and Alaska, USA (interior). We tested the hypothesis that the domestic herding practice of moving reindeer to spring-summer pasture on the coast is to allow reindeer to make up mineral balances that are negative during winter. This hypothesis was supported by data for Na and Cl, which were higher in 12 of 13 forage plants from the coastal region compared with inland areas. Analyses of other minerals, however, indicated a higher variability among plants than between regions. Aquatic plants from the coast and inland were higher in Na and Cl that terrestrial species. A high concentration of Co in willows was independent of region. Graminoids were low in Na and Cl, independent of region. Lichens were low in all macro minerals but were high in trace minerals. This study supported hypotheses based on salt hunger; namely, that the primary reason to move in coastal regions was to compensate for Na deficiency in winter. We suggest this movement also would maximize milk synthesis, which would otherwise be limited because of high Na content of reindeer milk. Selective foraging within coastal vegetation allows animals to meet requirements of macrominerals. Selective use of willows not only supports the high protein requirements of lactation and growth, but an adequate Co intake is required for synthesis of vitamin B12, critical for animal growth and rapid development of rumen function in young reindeer and caribou.
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