Reindeer, also known as caribou in North America, are fascinating creatures uniquely adapted to survive in the harsh Arctic and subarctic environments. Their diet plays a crucial role in their survival, influencing their weight, health, and reproductive success. This article delves into the intricate details of the reindeer diet, exploring what they eat, how their diet changes with the seasons, and the challenges they face in a changing climate.
Reindeer and Caribou: Same Species, Different Names
Before diving into the specifics of their diet, it's essential to clarify the terminology. Reindeer and caribou belong to the same species, Rangifer tarandus. In Europe, they are commonly referred to as reindeer, while in North America, the term caribou is typically used for wild populations, and reindeer for domesticated ones.
Seasonal Weight Fluctuations
Reindeer weight fluctuates throughout the year in accordance with the seasons. Once spring comes along in the tundra (around April) and plant life returns, herbivorous reindeer can graze to their hearts' content. As vegetarians, reindeer and caribou get their fill from the grasses and shrubs that grow in the tundra. Males reach their peak weight of around 220 pounds (100 kilograms) in August. At this point, they go "in rut," which means they begin mating. During the rut, males undergo significant physical changes, including neck swelling and mane growth, and may lose up to 25% of their body weight due to the stress of competition.
Antlers: A Defining Characteristic
Antlers are the reindeer’s most memorable characteristic. In comparison to body size, reindeer have the largest and heaviest antlers of all living deer species. A male’s antlers can measure up to 51 inches (130 centimeters) long, and a female’s antlers can reach 20 inches (50 centimeters). Just as a tree has a trunk, so all antlers have a main beam and several branches or tines that grow from the frontal bones of the skull. Sometimes little branchlets or snags are also present. The tip of each antler is called a point. Unlike horns, antlers fall off and grow back larger every year. As new antlers grow, the reindeer is said to be in velvet, because skin, blood vessels, and soft fur cover the developing antlers. Males begin to grow antlers in February and females in May. They both finish growing their antlers at the same time but shed their antlers at different times of the year. A male drops his in November, leaving him without antlers until the following spring, while female reindeer keep their antlers through the winter until their calves are born in May.
Summer Diet: A Diverse Menu
During the warmer months, when vegetation is abundant, reindeer enjoy a diverse diet. When available, they eat mosses, herbs, ferns, grasses, and the shoots and leaves of shrubs and trees, especially willow and birch. Soft juicy vegetation is preferred during the summer. Reindeer nibble, selecting the best when they can pick and choose. Leafy weeds, such as dandelions, seem to be a favourite of reindeer. The more dandelions, chickweed and such you have in your pasture, the more they thrive. They also do well in treed areas where they can browse a lot. They will eat leaves from willows, birch, poplar, maple and saskatoon bushes as well as many more. Reindeer are selective feeders and, if conditions permit, eat only the top portion of plants. Top-cropping plants, grasses, sedges, herbs and shrubs, the mainstays of their summer diet, stimulate annual growth therefore increasing pasture productivity. An adult caribou can eat as much as five kilograms of food each day.
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Winter Diet: The Lichen Staple
Once winter sets in and snow covers the tundra, the reindeer diet narrows down to one food: lichen. Lichen survives the cold winters because of its unique biological combination of algae and fungus. Reindeer sniff out lichen beneath the snow and use their curved hooves or antlers to uncover it. During this time, reindeer maintain more sedentary habits to preserve their energy. The lichen-only regimen is the reverse of the Atkins Diet. The plant contains high amounts of carbohydrates, but no protein. Consequently, the carbs provide the reindeer a source of quick-burning energy that carries them through winter. However, lichen isn't a particularly hearty food, and for that reason, reindeer will eat 4 to 11 pounds (1.8 to 4.9 kilograms) of reindeer moss each day. That's why reindeer pack on the pounds in the warmer months when there's more to choose from.
Lichens are “survival” food for reindeer and caribou in the winter. Alaska and Northern Canada lichens make up the bulk of the winter diet and without them, reindeer would starve. A special enzyme in their stomach breaks down lichen, an energy-rich food.
Adaptation to Cold Climates
Reindeer are built for staying warm in freezing temperatures. They originally inhabited the tundra and forests of Scandinavia and northern Russia, and were then introduced into Iceland, Greenland, Alaska, and Canada. Reindeer come in a variety of colors, depending on the subspecies, the region, the sex, and even the season. They range from dark brown in woodland subspecies to nearly white in Greenland. A reindeer’s coat is usually a bit darker in summer and lighter in winter. Reindeer have two coat layers: an undercoat of fine, soft wool that stays right next to their skin, and a top layer of long, hollow guard hairs. The air trapped inside the guard hairs holds in body heat to keep a reindeer warm against wind and cold. Having hairy hooves may look funny, but they give reindeer a good grip when walking on frozen ground, ice, mud, or snow. Spongy footpads help them walk in marshy fields, and in winter, their hooves harden so they can dig into the ice or snow and keep from slipping. Being broad, flat, and having two toes, a reindeer’s hooves also allow it to push water aside when it swims. The hooves are even used to scrape at snow while looking for food. Another outstanding feature is right under the reindeer’s nose-actually, it IS its nose! The specialized nose helps to warm incoming cold air before it enters the lungs, and it also works as a super sniffer! Its sense of smell helps the reindeer find food hidden under snow, locate danger, and recognize direction.
The Ruminant Advantage: Four Stomachs for Efficient Digestion
Caribou fall under the suborder of Ruminantia, a group of mammals with two-toed feet and four-chambered stomachs. Giraffes, deer, cattle, antelopes, sheep, and goats are also ruminants. These four separate stomach chambers help them digest the plant material they eat. A lot of this material contains cellulose, a complex carbohydrate that ruminants can’t break down and digest. Instead, when they first ingest food, it travels to the first chamber of their stomach and stays there for a while to soften. Later on, they regurgitate the food back into their mouths and chew it again to break down the cellulose content. Finally, they swallow it again and finish the process in the other three chambers of their stomachs, where microorganisms assist in digestion.
Nutritional Needs in Captivity
In captivity, limited information would indicate that reindeer thrive on a standard ruminant diet of good quality hay and supplement with pellets and grain in moderation. Outlined in the following is a basic view of the requirements of reindeer. Each producer has their own formulations of feed and what works for one may not work for another. It seems that this variance comes from the different types of soil and the different climate, even within the same province. You can normally feed 6-10 reindeer on what it takes to feed one beef cow. Reindeer will require 2.1% of their body weight in dry matter, rising to 4.7% during growing periods and lactation times. Nutrients in the feed are very important.
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The average crude protein content in a supplement is usually around 14%. Too much protein can cause problems, as can too little. This is based on the type of pasture you have for summer grazing and the type of hay fed in the winter months. In pastures that are in clover/alfalfas, deer will usually do well with a 14% crude protein supplement. Pastures that are in a poorer grass type (not as much protein as an alfalfa/clover mix) may want to up the supplement t0 15%. Pastures of different types and supplements of varying crude protein percent are being used with varying results.
Grains are also being used in the supplement part of their diet. The grains are mixed in with the supplement pellets and fed once or twice daily, depending on each producer. When using grain as an additive with the supplement pellets, it should be noted that too much grain is not good for reindeer. Studies in Sweden have showed that reindeer fed too much (or mainly) grains have had very thin rumens.
During mid-winter to early spring, reindeer will use their body reserves and lose considerable weight if no good pasture is readily available. Reindeer diets may be altered as the availability and costs of foodstuffs change. It must be remembered that any rapid change in diet can lead to digestive problems. The use of a probiotic may be useful to you in diet changing or simply weaning them into a new diet slowly.
Reindeer newly introduced to the farm should have hay or alfalfa made available to them on the ground. They are used to pawing for food and over concentrates in winter can cause the animal to become fat which may result in weak calves or calving problems. Reindeer do not readily eat hay from feeders, such as those used for round or square bales, because they cannot paw the feed. However, they will eat supplements and grains from feeders. They will still try to occasionally paw at the supplement and even in their water tanks.
Challenges to Reindeer Survival
Despite their adaptations, reindeer face numerous challenges, especially due to climate change and human activities.
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Climate Change
Recently, the changing climate has threatened the reindeer and caribou populations. Hotter temperatures have led to more rain and snow melt in the tundra regions. That, in turn, results in sheets of ice forming on top of the snow, once the water refreezes. With their seasonally influenced diet, the survival of reindeer depends on the balance of nature. If the weather is cold, freezing rains can create an impenetrable ice layer over vegetation so the deer cannot feed.
Warmer summers also mean more insect activity. In the hot summer, reindeer are harassed by warble flies, mosquitoes, black flies and other unpleasant insects which are so bothersome that they cause the deer to move constantly. Consequently, if not moved to or provided with an “insect free” area, the deer will loose weight because they will not stop to eat. TO get away from insects, reindeer will go to the most unprotected areas of pasture where the winds are the highest or to fully shaded areas where the insects are lower. Insect harassment begins to taper off in late July, allowing the herd to regain the weight they lost over the winter.
Human Activities
People are changing the tundra, too. Expanding oil exploration, industrial development, and increased disturbance from aircraft and snowmobiles are just some examples. So far, reindeer have been able to adapt to the presence of people and machines.
Habitat loss, degradation, and fragmentation, caused by human activity and climate change, pose a significant threat. Habitat changes impact vegetation, species distribution, hunting success rates, breeding habits, food availability, diseases, viruses, and more.
Predation and Disease
Depending on where they live, reindeer have to watch out for golden eagles, gray wolves, brown bears, Arctic foxes, mountain lions, coyotes, lynx, and dholes. A healthy adult reindeer is usually safe from predators, especially in a large herd, where many individuals can watch for danger. It is the youngest reindeer calves that are most susceptible to predation. Old, weak, ill, and injured reindeer are also vulnerable.
As temperatures rise, white-tailed deer move into areas occupied by reindeer. These deer carry a worm parasite that is fatal to moose and reindeer populations.
Conservation Efforts
Despite strict anti-hunting measures, poaching is still a major threat in Russia. In Finland, logging and winter sporting activities may disturb reindeer habitat. The conservation of reindeer emerges as a cultural imperative for Indigenous communities and a crucial climate solution for the broader global ecosystem. Their grazing habits help maintain the Arctic tundra ecosystem, preventing the release of stored carbon in the permafrost. Additionally, their presence promotes biodiversity, contributing to a resilient and balanced environment that can better withstand climate change impacts. Lastly, Indigenous communities’ traditional reindeer herding practices offer sustainable alternatives to more environmentally harmful land-use practices, fostering a harmonious coexistence between human activities and the fragile Arctic ecosystem.