Wolves, often admired and feared, play a vital role in maintaining healthy ecosystems. While folklore often portrays them as cunning villains, wolves are intelligent, social animals with complex emotions and a flexible diet that has allowed them to thrive across the Northern Hemisphere. This article explores the multifaceted diet of wolves, examining their preferred prey, adaptive eating habits, and the ecological implications of their food choices.
Wolves as Keystone Predators
Wolves are the largest members of the dog family, classified as carnivores. Their historical range covered a significant portion of the United States, making it inaccurate to limit their diet to a single animal. Federal conservation projects have helped ensure that these awe-inspiring creatures did not go the way of the Dodo. Wolves are a keystone species whose hunting and eating patterns play a crucial role in maintaining a healthy ecosystem.
Primary Prey: Ungulates
Despite popular belief, wolves do not solely hunt small animals like snowshoe hares or beavers. Their primary food source and preferred meat are ungulates, hoofed mammals such as deer, elk, moose, or bison. Wolves, being “coursing carnivores,” run long distances after their prey. A pack’s hunting territory can often be as large as 50 square miles. The type and abundance of wild ungulate species vary across the Northern Hemisphere, influencing wolf diets accordingly. Arctic wolves hunt caribou and musk-oxen, while elk, moose, deer, bighorn sheep, and mountain goats are the mainstays for wolf packs in Idaho, Montana, and Wyoming. The Mexican gray wolf favors elk and deer, while the red wolf in North Carolina hunts white-tailed deer. In parts of Spain and Italy, wolves feast on red deer, roe deer, and wild boar, while in Central Asia, the ibex, argali sheep, and wild goats are their primary prey.
Hunting large ungulates such as elk, moose, caribou, and musk-oxen is much easier and safer for wolves that hunt in packs, although records exist of single wolves killing prey animals. Hunting and killing a large ungulate takes skill, energy, and luck, and though wolves are skilled hunters, they are not always successful.
Dietary Flexibility and Opportunistic Predation
Unlike obligate carnivores, such as felines, wolves possess the digestive capabilities needed to synthesize plant-based food. These creatures are known to eat berries, apples, carrots, and melons, with about 20% to 30% of their overall diet consisting of vegetarian fare. These fruits and vegetables supply wolves with valuable nutrients missing in meat, such as Vitamin C, carbohydrates, and flavonoids.
Read also: The Hoxsey Diet
Another reason why wolves are so resilient is that they are opportunistic predators. This trait means that they will eat any creature that crosses their path. No animal is too large or too small for it. That is why it is hard to identify a wolf's main prey. This can vary from a mighty 1000-pound bison (that's over 400 kilograms of food) to a humble 3-pound rabbit and anything in between. This versatile and all-inclusive diet is not because they are the gastronomes of the wild. Rather, it is the result of factors such as weather conditions and seasonal availability. Given a choice, wolves would gorge on ungulates 365 days a year.
Wildlife biologists and paleontologists credit the wolf’s flexible diet, in part, for its success as a species, allowing it to survive and thrive in a range of ecosystems across the Northern Hemisphere, from grasslands to the vast, dry Arctic tundra.
Over half a century of research on wolves reveals that they also prey on smaller animals such as beavers, hares, marmots, and rodents, along with fish and even birds. Wolves scavenge, too, eating carrion and garbage.
Seasonal Variations in Diet
What wolves eat depends on the type of prey available, its size, and its vulnerability. Wolves' diets are heavily influenced by seasonal changes.
While many animals struggle to negotiate the travails of winter, wolves thrive during this season. There are several reasons this is so. For one, as the temperature drops, they develop a double layer of thick fur. This protective double layer helps them survive frigid temperatures as low as -35⁰ F. For another; they have large, wide feet that act akin to snowshoes, allowing them to traverse uninhibited even in deep snow. Conversely, ungulates have smaller, hooved feet that make navigating deep or crusty snow a cumbersome process. Wolves, being the intelligent creatures that they are, will often work to trap their prey in a pocket of deep snow, thereby increasing their chances of catching it exponentially. Not only that, due to the sparse grazing opportunities, the prey is also usually at their weakest during the more severe winter months. This combination of weak prey and superior winter biology work out in the wolves’ favor more often than not.
Read also: Walnut Keto Guide
Late winter and early spring bring with it the wolves’ mating and reproduction seasons. Alpha females typically give birth to pups in April inside a den. This family den becomes an anchor that keeps the wolf pack tied to an area. Consequently, they are restricted to eating whatever prey is available within their territory. Spring also brings with it fruits and vegetables. During this time, wolves will eat everything from squirrels and gophers to insects and berries and any ungulates they can find. They are even known to hunt for freshwater fish.
As summer rolls around, the mother and young pups emerge from the den. The wolf pack is hence free to move away from their focal point and can now explore and hunt the full length and breadth of their territory. However, as any parent will tell you, traveling with young ‘uns is never easy. They tire easily, need frequent breaks, and are prone to wandering off on a whim. This behavior is no different for the wolf family. The adults in the pack now shoulder more responsibility. Compounding this, they no longer hold any biological advantage over their prey as they did in the wintertime. Despite a wolf’s much-touted status as a premier hunter, most of their prey can easily outrun them. You would then think that a wolf's primary prey is a somewhat slow animal but in actuality, wolves have a success rate of only 3% to about 14% when they give chase. Fortunately for them, summertime is also the time when ungulates breed and give birth to their young.
Come fall, wolves look to fatten themselves up once again for the upcoming winter season. Wanting to stay close to their prey, a lot of wolf packs migrate along with their prey, picking off the weak and elderly among them along the way. Those close to streams are also known to hunt for salmon as and when they come upstream. There are several reasons that wolves switch from their preferred prey of hoofed animals to catching salmon. First, catching fish is a lot less risky than hunting ungulates and takes up only a fraction of the energy needed too. Second, being fatty, salmon is a good way for the pups to put on some weight before winter hits.
The Diet of Wolf Pups
Wolf pups, which are born after a gestation period of just over two months, come into this world completely and utterly helpless. They weigh a measly 1 pound at birth, are blind and deaf, and have little sense of smell. As such, they are wholly dependent on their mother. During this time, their eyes and ears open, and they stumble and bumble their way around the den, getting stronger and more coordinated with every passing day. Wolf pups gain weight rapidly at a rate of 2.5 to 3.5 pounds every week. At five weeks of age, though, their jaws and digestive system have not yet developed enough to chew and digest raw meat. So, a pup’s first taste of meat comes in the form of regurgitated meat brought back by the adults in the pack. So wolves don't bring back their prey to the den: the adult pack members swallow meat and when they come back from a hunt, the pups instinctively ‘ask’ for food. They do this by adopting a completely different body language, whining, pawing, and licking the adult’s mouth. This behavior causes the older wolves to regurgitate or throw up portions of the food already present in their stomach. As disgusting as this may sound to us, it is a foolproof way for the wolves to bring back food to the pups safely. For the next 3 to 4 weeks, wolf pups alternate between eating regurgitated meat and drinking their mother’s milk. The mother wolf fully weans her pups only when they are 8 to 10 weeks old. Once weaned, the pups can move on to eating raw meat by themselves. This period is when the pack moves away from the den, and the pups start going on short hunting trips with the rest of their family.
Hunting Strategies and Teamwork
Though they usually sit at the top of the food chain in any given area, wolves have some biological limitations restricting their hunting capabilities. Deer have a top speed of about 50 miles per hour. In comparison, the wolves’ shorter limbs mean they peak at about 40 miles per hour. Ungulates are also almost always bigger than wolves. But what the wolves lack in pace and size, they make for up with stamina and teamwork. The wolf pack works together collaboratively to, first, identify their prey. Given that there is a high chance of getting injured or simply being outrun if they pick a healthy ungulate, wolves tend to go for the weaker, easier to ambush animals. They will then patiently isolate and hound their target if they need to, sometimes following them for miles, until the prey eventually tires out. This time is when they move in for the kill. What is extraordinary is that this coordinated effort takes place with little to no verbal communication or signals.
Read also: Weight Loss with Low-FODMAP
Wolves can survive on 2.5 to 3.7 pounds of meat daily, but they require 5 to 7 pounds per day for successful reproduction. Yet wolves typically do not eat every day. Instead, they live a feast-or-famine lifestyle. To survive, adult wolves need a minimum of around 2 to 3 pounds of meat every day. However, for growing and reproducing wolves, this minimum amount increases twofold due to their advanced nutritional requirements. That said, wolves very rarely eat every day. They have a feast-or-famine style of consumption. Conversely, they can consume a whopping 20 to 22 pounds of meat in one sitting! Quite different from a dog's diet, right? Their stomachs can hold a massive amount of food, allowing them to gorge when necessary. If push comes to shove, wolves will scavenge and eat carrion, though they prefer not to.
The Impact of Wolves on Ecosystems
When it comes to creating a balanced ecosystem, wolves play a starring role. Wolf predation may represent compensatory or additive mortality. Their habit of picking off the weaker members of the ungulate population acts as a form of natural selection. It ensures that only the healthy among them survive. Besides, the very presence of a wolf pack causes the ungulate population to move away in search of safer pastures, thereby allowing the vegetation in that area a chance to flourish. Sensing the fierce predators’ presence, the deer population moved to the periphery of the park, allowing the vegetation to grow lush. This, in turn, saw the population of everything from birds and beavers to berry-loving bears increase. Even though their numbers were small, the reintroduced wolves had a cascading effect on the Yellowstone ecosystem, causing it to thrive and become more diverse.
Case Studies of Wolf Diets in Different Regions
Several studies highlight the diverse diets of wolves in different regions and their adaptability to changing prey availability.
- Isle Royale: For over half a century, Isle Royale has been the focus of the longest-running predator-prey study on wolves. From 1959 to 1980, the moose and wolf populations of Isle Royale tended to reflect each other. When the moose numbers were high, there was more food for the wolves, meaning better nutrition, higher pup survival rates, and an increase in the wolf population. More wolves eventually led to a decline in moose and less food for wolves, meaning fewer wolves survived. As wolf numbers declined, they put less pressure on the moose populations, which in turn helped moose numbers rebound, and the cycle repeats.
- Minnesota: In the east-central Superior National Forest in northeastern Minnesota, white-tailed deer, moose, and beavers are the top menu items for wolves. From 2006 to 2016, the moose population declined by more than half. A study tracked and counted radio-collared wolves, showed that as the moose population declined, the wolf population, instead of decreasing, almost doubled. Wolf scat revealed that wolves supplemented their diets by hunting white-tailed deer. They also continued to prey on moose calves, contributing to the continuing decline of the moose population.
- Alexander Archipelago, Alaska: A recent study focused on what the wolves of the Alexander Archipelago and the southeastern mainland of Alaska eat when ungulates became scarce or absent. From 2012 to 2018, researchers collected 860 wolf scats from twelve study sites. DNA analysis of the wolf scat identified 55 food sources in the wolves’ diet. Although the study confirmed that ungulates represented roughly 65% of the wolves’ diet on a regional level, it also revealed that the kind and proportion of ungulates in their diets varied from one location to another. For instance, on the mainland, wolves’ main prey were moose and mountain goats, while on several of the islands, Sitka black-tailed deer were the main prey. As in other studies, when one of these ungulates went into decline or became scarce, wolves changed the prey that they hunted or scavenged. In several other locations ungulates were not the main items on the wolf’s menu. For instance, the wolves who inhabit the area near Gustavus, on the shores of mainland Alaska, had the most varied diet. Here, moose comprised only 28% of the wolves’ diet, while sea mammals (mostly sea otters) comprised 22%. Black bears represented another 11% of their food while seasonally salmon made up 10% of their diet. The researchers suggest that the wolves opt for these other species because they are less dangerous and easier to hunt than moose. Southeast of Gustavus, in the Icy Straits, lies Pleasant Island where both Sitka black-tail deer and moose are found. Wolves arrived on Pleasant Island in 2013, and moose and deer numbers went into decline. Yet, despite the scarcity of these ungulates, wolves remained on the island. Scat analysis revealed that moose and deer made up only 13% of the wolves’ diet.
- Human-Related Food Sources: Where wild prey is unavailable, one of the food sources that wolves turn to is domestic livestock, bringing them into direct conflict with humans. Garbage represents another human-related food source for wolves. Scat analysis of wolves in Israel reveals that wolves consume not only meat scraps and fruit, but in the process also incidentally down non-food trash items such as human hair, plastic containers, cigarettes and eggshells. Dave Mech once found shards of broken glass in wolf scats. In Italy, prior to the restoration of large prey species, wolves often relied on town garbage dumps. A more recent study studied the diets of wolves in the Hamadan province of Western Iran, where livestock (sheep and goats) and agriculture are the main sources of income. It is also a region where medium-to-large wild prey are extremely scarce. Using GPS collars, researchers tracked and identified 312 wolf feeding sites, most of which were garbage dumps and poultry farms near villages. Of these, 142 kill sites and 170 other sites contained evidence of scavenging.
- Fruits: Fruit is yet another food for wolves. Various studies of scat from the 1970s through the 1990s revealed fruit such as cherries, berries, apples, pears, figs, plums, grapes and melon in wolves’ diets across southern Europe (Italy, Greece, Spain and Portugal), Eastern Europe (Czech and Russia) and China.