Svalbard reindeer diet-switch from moss to grass supports reindeer population growth in the face of dramatic winter and summer climate changes in the High Arctic

UArctic Research Chair, Professor Jeff Welker, PhD student Tamara Hiltunen and colleagues have discovered the potential mechanism behind the surprising increase in High Arctic Svalbard Reindeer populations published recently in Global Change Biology.
Svalbard reindeer female and calf
Svalbard reindeer female and calf. Photo: Erik Ropstad

On Svalbard, a group of islands in the Barents Sea, with some of the worlds northerly most land and icescapes (~78-80 degrees north), climate warming has been occurring at 4 times the planetary averages, as the High Arctic switches to becoming more and more a rain dominated in winter system with warmer summers. These winter-rain, or rain on snow events (ROS) have historically been the demise of caribou and reindeer across the Arctic. However, the combination of summer and winter warming has led to vegetation shifts on Svalbard whereby erect grasses, as opposed to flat patches of moss are becoming increasingly dominate.

Using a long-term set of Svalbard reindeer blood samples collected at the end of winter by Norwegian colleagues from the Nature Institute of Norway, University of Oulu Finland PhD student Tamara Hiltunen and Professor Welker have documented a Svalbard reindeer winter-diet switch from moss to grass. This diet switch appears to have coincided with a growth in the populations even as icing (ROS) of a few cm covers the low growing moss but the erect stems and leaves of grasses are protruding above the ice layer and being eaten by the reindeer in winter.

These findings depict the complexity of the High Arctic, the interactions between winter and summer climate changes, vegetation responses to a new Arctic and the foraging ecology adaptation of one of the world’s most iconic Arctic species, the Svalbard Reindeer.

Welker says that these findings on Svalbard have relevance to Lapland reindeer: "Forage biodiversity on the landscape reindeer graze, may provide a buffer to negative effects of climate change in Northern Finland. While some forage species may decline, others forage species or lifeforms may flourish and become a larger part of reindeer diets, facilitating the sustainability of reindeer populations in the future."

Other coauthors of this research are: Professor Jouni Aspi and Dr. Maria Väisänen from the University of Oulu; Professor Audun Stien, UiT The Arctic University of Norway; & Dr. Erik Ropstad, Norwegian University of Life Sciences. Research article: Svalbard reindeer winter diets: Long-term dietary shifts to graminoids in response to a changing climate. Global Change Biology, 00, 1–14.

The new research publication is part of a larger research project led by Professor Welker, "Interacting processes in Arctic reindeer systems experiencing rapid climate change" funded by the University of Oulu's Kvantum Institute. The interdisciplinary research will investigate the impacts of climate change on reindeer and caribou ecology, greenhouse gas emissions from reindeer herding and reindeer husbandry.

This research is supported in part by Professor Welker’s UArctic (University of the Arctic) Chairship that involves a joint appointment between the University of Oulu and the University of Alaska Anchorage.

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Last updated: 19.6.2024