Reindeer Nutrition

Reindeer (Rangifer tarandus tarandus) and Forest Reindeer (Rangifer tarandus fennicus) are unique northern ruminants. They have distinctive and prominent adaptations for surviving in harsh, seasonal environment. Even in captivity, far away from their native habitats, they show physiological changes aimed to respond to seasonal changes. Because of this they need appropriate, seasonal diets in captivity. In this article we will cover the basics of reindeer nutrition. In next articles we will dive more deeply in to summer and winter diets and finally we will look at how this can be managed in captivity to have healthy animals.

Reindeer and forest reindeer side by side
Reindeer and forest reindeer side by side, can you tell them apart? Ähtäri Zoo, 2017.

R.t.tarandus and R.t.fennicus are subspecies of the reindeer Rangifer tarandus. They differ in appearance in that the forest reindeer has longer legs and narrower antlers. Their diet is thought to be similar, though there is insufficient data on forest reindeer’s natural diet. Some estimation can be made based on what type of forage is available in Finnish forests and wetlands. In captivity both subspecies seem to thrive on the same diet. In this article we talk about reindeer nutrition, but this can be applied to both subspecies equally.

How do they eat?

Before we can address the diet of reindeer, we need to look at their digestive system and strategies. So far, we have established that reindeer is a ruminant, meaning that it relies most of its digestion on microbes living in its forestomaches. When we feed a ruminant, we are feeding its gut microbiota, which turn feed they eat into units the ruminant can use. Most important ones are volatile fatty acids (VFA’s) for energy and microbial protein what basically means dead microbes that leave the forestomaches and get digested and absorbed by the ruminant.

Nutritional strategies of ruminants

Ruminants can be classified as browsers, intermediates or grazers. Instead of individual boxes these classifications are more like a spectrum where a ruminant species is placed based on its diet and some physical characteristics of its digestive tract. Many of the intermediate ruminant species can move along this spectrum to adapt to changes in food availability in their habitat. Species in each extreme are more fixed to their strategy. Reindeer is one of these intermediate ruminants that can travel along the spectrum. This makes it an adaptable survivor of the north.

Rangifer tarandus fennicus female and calf in Helsinki Zoo

Seasonal changes

Rangifer tarandus has an almost circumpolar distribution across the northern countries. Seasons are very distinctive in these areas: winter is long, dark and cold where as summer is short, light and warmer. In the summer the vegetation is plentiful, fresh and nutritious. In the winter there isn’t nothing much to eat, so reindeer has adapted to eat lichen that can be uncovered from snow. Reindeer move in large heard that can have tens of thousands of individuals. They move between winter pastures and summer calving grounds/summer pastures.

Metabolic changes

In order to survive on changing diet the reindeer has to be able to conserve energy and protein in the winter and accumulate body reserves during the summer. Physiological changes in metabolism that happen to facilitate survival need to happen before the amount of food starts to decrease in the late autumn. If decreasing food would be the trigger to start the process of moving to winter metabolism, it would be too late and energy would be lost. For this reason, the metabolic changes are regulated by hormonal cascade that is regulated by melatonin. Melatonin production is regulated by the amount of light, and in the north the changing amount of light is a big and visible indicator of changing season.


In the winter the reindeer eat less, spend less time foraging for food and their energy balance is negative through the winter. Reindeer start to mobilize body reserves accumulated during summer and autumn. The calves growth arrests during winter, because just the maintenance of body functions takes all the energy available. They continue growing when the energy balance is turned to positive again. In the winter there is little food available and digging it up from snow can take a lot of energy. Especially late winter is a time of famine.


When winter turns to spring and summer the amount of light begins to increase. Food intake and foraging increase and the reindeer start a migration to their summer pastures. In the summer they eat more food that is more nutritious than in the winter. During summer and autumn they accumulate body reserves to help them make through next winter.

What’s next?

Now we have covered the basic idea of reindeer nutrition. Most important things to remember are:

  • Reindeer is an intermediate ruminant
  • Reindeer’s habitat changes tremendously between seasons
  • To survive in changing environment the reindeer has to change its diet
  • Physiological changes happen whether or not the diet changes
  • Summer is nutritionally important because body reserves determine survival in winter

Next we will dig in to summer and winter diets in the wild. See you there!

P.s. If you have questions or comments don’t be afraid to shoot me a message! Contact me here or email aino [a]

References & further reading

Barboza, P. & Parker, K. 2006, Body Protein Stores and Isotopic Indicators of N Balance in Female Reindeer (Rangifer tarandus) during Winter, Physiological and Biochemical Zoology, 79 (3), s. 628-644.

Boertje, R.D. 1990, Diet Quality and Intake Requirements of Adult Female Caribou of the Denali Herd, Alaska, Journal of Applied Ecology, 27 (2), s. 420-434.

Case, R.L. 1997, Adaptations of northern ungulates to seasonal cycles in nitrogen intake., dissertation, University of Alberta.

Clauss, M., Hofmann, R.R., Streich, W.J., Fickel, J. & Hummel, J. 2010, Convergence in the macroscopic anatomy of the reticulum in wild ruminant species of different feeding types and a new resulting hypothesis on reticular function, Journal of Zoology, 281 (1), s. 26-38.

Clauss, M., Hofmann, R.R., Fickel, J., Streich, W.J. & Hummel, J. 2009, The intraruminal papillation gradient in wild ruminants of different feeding types: Implications for rumen physiology, Journal of morphology, 270 (8), s. 929-942.

Danell, K., Utsi, P.M., Palo, R.T. & Eriksson, O. 1994, Food Plant Selection by Reindeer during Winter in Relation to Plant Quality, Ecography, 17 (2), s. 153-158.

Heggberget, T.M., Gaare, E. & Ball, J.P. 2002, Reindeer (Rangifer tarandus) and climate change: Importance of winter forage, Rangifer, 22 (1), s. 13-31.

Heiskari, U. & Nieminen, M. 1992, The effect of the diet on the digestive organ size of reindeer, Rangifer, 12 (3), s. 167-168.

Hofmann, R.R. 2011, Functional and comparative digestive system anatomy of Arctic ungulates, Rangifer, 20 (2-3), s. 71-81.

Hofmann, R.R. 1989, Evolutionary Steps of Ecophysiological Adaptation and Diversification of Ruminants: A Comparative View of Their Digestive System, Oecologia, 78 (4), s. 443-457.

Joly, K., Wasser, S.K. & Booth, R. 2015, Non-invasive assessment of the interrelationships of diet, pregnancy rate, group composition, and physiological and nutritional stress of barren-ground caribou in late winter, PLoS ONE, 10 (6).

Josefsen, T.D., Aagnes, T.H. & Mathiesen, S.D. 1996, Influence of diet on the morphology of the ruminal papillae in reindeer calves (Rangifer tarandus tarandus L.), Rangifer, 16 (3), s. 119-128.

Klein, D.R. 1990, Variation in quality of caribou and reindeer forage plants associated with season, plant part, and phenology, Rangifer, 10 (3), s. 123-130.

Maijala, V., Heiskari, U. & Nieminen, M. 2004, The adaptation of the digestive system of a reindeer to a yearly additional feeding, Finnish Game and Fisheries Research Institute, Helsinki.

Mathiesen, S.D., Vader, M.A., Raedergård, V.B., Sørmo, W., Haga, O.E., Tyler, N.J. & Hofmann, R.R. 2000a, Functional anatomy of the omasum in high Arctic Svalbard reindeer (Rangifer tarandus platyrhynchus) and Norwegian reindeer (Rangifer tarandus tarandus). Acta Vet Scand, 41 (1), s. 25-40.

Mathiesen, S.D., Haga, ØE., Kaino, T. & Tyler, N.J.C. 2000b, Diet composition, rumen papillation and maintenance of carcass mass in female Norwegian reindeer (Rangifer tarandus tarandus) in winter, Journal of Zoology, 251 (1), s. 129-138.

Nieminen, M. 1980, Nutritional and seasonal effects on the haematology and blood chemistry in reindeer (Rangifer tarandus tarandus L.), Comparative Biochemistry and Physiology — Part A: Physiology, 66 (3), s. 399-413.

Nieminen, M. & Heiskari, U. 1989, Diets of freely grazing and captive reindeer during summer and winter, Rangifer, 9 (1), s. 17-34.

Ophof, A.A., Oldeboer, K.W. & Kumpula, J. 2013, Intake and chemical composition of winter and spring forage plants consumed by semi-domesticated reindeer (Rangifer tarandus tarandus) in Northern Finland, Animal Feed Science and Technology, 185 (3-4), s. 190.

Podterob, A. 2008, Chemical composition of lichens and their medical applications, Pharmaceutical Chemistry Journal, 42 (10), s. 582-588.

Pösö, A.R., Heiskari, U., Lindström, M., Nieminen, M. & Soveri, T. 2001, Muscle fibre growth in undernourished reindeer calves (Rangifer tarandus tarandus L.) during winter, Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, 129 (2), s. 495-500.

Rankama, T. & Ukkonen, P. 2001, On the early history of the wild reindeer (Rangifer tarandus L.) in Finland 30, Blackwell Publishing Ltd, s. 131-147.

Säkkinen, H., Timisjärvi, J., Eloranta, E., Heiskari, U., Nieminen, M. & Puukka, M. 1999, Nutrition-induced changes in blood chemical parameters of pregnant reindeer hinds (Rangifer tarandus tarandus), Small Ruminant Research, 32 (3), s. 211-221.

Sjaastad, ØV., Hove, K. & Sand, O. 2010, Physiology of domestic animals, 2nd ed. p., Scandinavian Veterinary Press, Oslo.

Sørmo, W. & Mathiesen, S.D. 1993, Bacteria in the small intestine of lichen-fed Norwegian reindeer (Rangifer tarandus tarandus), Letters in Applied Microbiology, 16 (3), s. 170-172.

Soveri, T. & Nieminen, M. 2007, Papillar Morphology of the Rumen of Forest Reindeer (Rangifer tarandus fennicus) and Semidomesticated Reindeer (R. t. tarandus), Anantomia Histologia Embryologia, 36 (5), Blackwell Publishing Ltd, s. 366-370.

Soveri, T., Sankari, S. & Nieminen, M. 1992, Blood chemistry of reindeer calves (Rangifer tarandus) during the winter season, Comparative Biochemistry and Physiology — Part A: Physiology, 102 (1), s. 191-196.

Staaland, H., Jacobsen, E. & White, R.G. 1979, Comparison of the Digestive Tract in Svalbard and Norwegian Reindeer, Arctic and Alpine Research, 11 (4), s. 457-466.

Thompson, D.P. & Barboza, P.S. 2017, Seasonal energy and protein requirements for Siberian reindeer (Rangifer tarandus), Journal of Mammalogy, 98 (6), s. 1558-1567.

Thompson, D.p. & Barboza, P.s. 2013, Responses of caribou and reindeer ( Rangifer tarandus) to acute food shortages in spring, Canadian Journal of Zoology, 91 (9), s. 610-618.

Valtonen, M. 1979, Renal responses of reindeer to high and low protein diet and sodium supplement, University of Helsinki.

Warenberg, K., Dannel, Ö, Gaare, E. & Nieminen, M. 1997, Porolaidunten kasvillisuus, Pohjoismainen Porontutkimuselin (NOR), Landbruksforlaget.

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White, R.G., Jacobsen, E. & Staaland, H. 1984, Secretion and absorption of nutrients in the alimentary tract of reindeer fed lichens or concentrates during the winter, Canadian Journal of Zoology, 62 (12), s. 2364-2376.

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