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.
The nutritional state of animals is tightly linked to the ambient environment, and for northern ungulates the state strongly influences vital population demographics, such as pregnancy rates. Continuously growing tissues, such as hair, can be viewed as dietary records of animals over 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 able to reconstruct the dietary history of muskoxen over approximately 2.5 years with a high temporal resolution of app. 9 days. The dietary chronology included almost three full summer and winter periods. The diet showed strong intra- and inter-annual seasonality, and was significantly linked to changes in local environmental conditions (temperature and snow depth). The summer diets were highly similar across years, reflecting a graminoid-dominated diet. In contrast, winter diets were markedly different between years, a pattern apparently linked to snow conditions. Snow-rich winters had markedly higher δ15N values than snow-poor winters, indicating that muskoxen had limited access to forage, and relied more heavily on their body stores. Due to the close link between body stores and calf production in northern ungulates, the dietary winter signals could eventually serve as an indicator of calf production the following spring. Our study opens the field for further studies and longer chronologies to test such links. The method of sequential stable isotope analysis of guard hairs thus constitutes a promising candidate for population-level monitoring of animals in remote, arctic areas.
Arctic Research Centre, Department of Bioscience, Aarhus University, Frederiksborgvej 399, DK-4000 Roskilde, Denmark.
Jesper Bruun
JB
Mosbacher
Department of Biology, University of Copenhagen, Universitetsparken 15, DK-2100 Copenhagen Ø, Denmark.|Center for Permafrost, University of Copenhagen, Øster Voldgade 10, DK-1350 Copenhagen K, Denmark.
Anders
A
Michelsen
Copenhagen Zoo, Roskildevej 38, DK-2000 Frederiksberg, Denmark.
Mikkel
M
Stelvig
Norwegian Institute of Nature Research, Høgskoleringen 9, NO-7034 Trondheim, Norway.
Ditte Katrine
DK
Hendrichsen
Arctic Research Centre, Department of Bioscience, Aarhus University, Frederiksborgvej 399, DK-4000 Roskilde, Denmark.
Niels Martin
NM
Schmidt
D000818:Animals; D001188:Artiodactyla; D002081:Buttocks; D004032:Diet; D006197:Hair / Q000737:chemistry*; D009587:Nitrogen Isotopes / Q000032:analysis; D012621:Seasons
D009587:Nitrogen Isotopes