Muskoxen rump hairs
from muskoxen reveal winter shortage of forage. A new study in the open-access journal PLoS ONE demonstrates through analysis of hairs from muskoxen that these large herbivores in the arctic tundra had limited amounts of forage available and relied heavily on body stores during snow-heavy winters
In collaboration between scientists from CENPERM, Aarhus University, Norwegian Institute of Nature Research and Copenhagen Zoo, guard hair samples were clipped from the rumps of 10 muskoxen in Zackenberg, Northeast Greenland, and isotope analysis was used to reconstruct their diets over the previous two and a half years, with a resolution of about nine days.
Continuously growing tissues, like hair, provide a long-term record of animal diets in the form of δ15N, a nitrogen isotope that may vary depending upon the food source, and muskoxen guard hairs grow continuously for several years. Muskoxen feed mainly on grasses and willows, which have different isotopic signatures, and while grasses are more available during summer, willow twigs is the main food source in winter.
The diets of muskoxen were closely linked to changes in the temperature and snow depth. While summer diets were similar from year to year, winter diets varied widely, likely caused by large variations in the snow depth between winters. In particular, increased δ15N values were seen in muskoxen guard hair in winters with heavy snowfall. This indicated that the muskoxen had very limited access to forage and relied more heavily on their body stores to get through these extreme winters.
The study shows that isotope levels in hair may be used as an indicator of winter diet quality and body condition. Due to the close link between body condition and the production of calves, this method may help in the monitoring of difficult-to-access animal populations, particularly in areas undergoing marked changes in climate.
The study is part of Jesper Mosbacher’s PhD thesis at Aarhus University. The work was done under guidance by senior scientists Niels M Schmidt, Aarhus University, and Professor Anders Michelsen, CENPERM, with the stable isotope analysis done at Department of Biology, University of Copenhagen
Link to scientific paper in PloS ONE here:
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Link to Videnskab.dk here (in Danish):
Link to dr.dk here (in Danish): http://www.dr.dk/nyheder/viden/miljoe/ny-teori-plantevaekst-i-arktiske-egne-kan-haemme-global-opvarmning