Determinants of blood water δ18O variation in a population of experimental sheep: Implications for paleoclimate reconstruction

We investigate controls on blood water δ18O values in population of large herbivores. We find that seasonal δ18O variation and fractionated water loss scale with ambient temperature. With constant inputs, population blood δ18O values vary by 0.40‰ at a single time point, and by 0.72‰ (1 s.d.) for single sheep over time. These results set a baseline for expected variation in fossil herbivore populations, impacting δ18O -based physiological, hydrological and temperature reconstructions.245