Show Me Your Rump Hair and I Will Tell You What You Ate – The Dietary History of Muskoxen (Ovibos moschatus) Revealed by Sequential Stable Isotope Analysis of Guard Hairs

摘要

The nutritional state of animals is tightly linked to the ambient environment, and for northernungulates the state strongly influences vital population demographics, such as pregnancyrates. Continuously growing tissues, such as hair, can be viewed as dietary records of animalsover longer temporal scales. Using sequential data on nitrogen stable isotopes (δ15N)in muskox guard hairs from ten individuals in high arctic Northeast Greenland, we were ableto reconstruct the dietary history of muskoxen over approximately 2.5 years with a high temporalresolution of app. 9 days. The dietary chronology included almost three full summerand winter periods. The diet showed strong intra- and inter-annual seasonality, and was significantlylinked to changes in local environmental conditions (temperature and snowdepth). The summer diets were highly similar across years, reflecting a graminoid-dominateddiet. In contrast, winter diets were markedly different between years, a pattern apparentlylinked to snow conditions. Snow-rich winters had markedly higher δ15N values thansnow-poor winters, indicating that muskoxen had limited access to forage, and relied moreheavily on their body stores. Due to the close link between body stores and calf productionin northern ungulates, the dietary winter signals could eventually serve as an indicator ofcalf production the following spring. Our study opens the field for further studies and longerchronologies to test such links. The method of sequential stable isotope analysis of guardhairs thus constitutes a promising candidate for population-level monitoring of animals inremote, arctic areas.