Who Is Really the Top Dog

Most predators are solitary individuals. Leopards, tigers, grizzly bears, bald eagles, etc. But then there are those that are not. Lions are one example. African wild dogs are another. And then there is the wolf.

At first glance, working as a team doesn’t make a whole lot of sense for an apex predator. You can take down and kill all on your own. Sure, this is an easier task when you can work with others. But every mathematical equation ever conjured up to study the economy of calories in predators points to the same thing: any number greater that 2 predators working together produces a net loss.

This makes sense, of course.

More animals and a group mean more mouths to feed.

Two wolves are more efficient at taking down an elk, for instance, than one. There is less effort. Less calories spent. Less chance of being killed by that elk – and yes, wolves are routinely killed while attempting to hunt.

But here in Yellowstone, there are packs of wolves with over 20 members in the pack.

This is a conundrum that researchers have puzzled over for many years. Of course, in nature, very little happens on accident. With all of the selective pressures and hardships of life in the wild, a pack of wolves doesn’t just “accidentally” swell to such great numbers.

This isn’t a Yellowstone thing though either. Wolves live in packs. We all know that. Just like we know that lions live in prides.

And then one day, a couple researchers working in Michigan’s Isle Royal studying wolf – moose dynamics tried to reframe the way they were looking at the bigger pictured and wondered if it was actually the presence of other animals that drove this behavior.

Lions, for instance, benefit from living in larger groups not just because it makes life easier trying to take down big prey. A large pride more importantly stands a better chance at also defending their kill from hyenas.

Bernd Heinrich, a biologist at the University of Vermont, and author of the best-selling book, Mind of the Raven, has studied ravens for a longtime. When it comes to the lives and times of these giant black birds, Heinrich is the world authority. And in his studies, at places such as Isle Royal and Yellowstone, he has documented that ravens are present at wolf kills 99.7% of the time.

So, John Vucetich and Rolf Peterson, the two researchers from Isle Royal, began to question whether or not the ever-present ravens themselves might be playing some other roll than we realized. And to start, they began looking at meant consumption.

A wolf can consume up to 13lbs of meat a day from a carcass. A raven, on the other hand, can only consume about 2lbs of meat, but they also typically cache an additional 2lbs a day to be able to come back to – equally about 4lbs of meat a day.

This is all simple math. Obviously, the wolf consumes far more meat than a raven does.

However, when we take into consideration that there is sometimes more than 100 ravens lingering around wolves and their kill, this changes things considerably.

With a hypothetical 100 ravens disappearing 4lbs of meat a day, that’s 400lbs of meat that go missing from a single carcass in a 24hr period of time thanks to those ravens.

This is more than what 30 wolves can consume in a single day!

So, given the difficulty of taking down a large animal to begin with, the risks to life and limb, the calories spent, etc. And given the fact that a flock of ravens truly consumes the “lion’s share” of any wolf kill, the larger the pack of wolves the more meat the pack itself gets from the buffet before it’s all gone.

This still doesn’t benefit an individual wolf. Or a mated pair (the alphas). Now, not only do they have to give up most of their meat to ravens, they also have to give up the rest of the meat to pack members.

But the other side of the equation here is that the larger the pack, the more easily they can hunt together. The faster they can ultimately kill again. And the larger the prey they can take down by working in unison together.

So, a large pack of wolves, such as the Wapiti Pack featured in the photograph above, can kill and elk, “wolf” down as much meat as possible in 1 – 2 days before the ravens take it all, then move on to kill another elk within the next few days. Sure, each individual wolf gets less per kill. But because they can be more efficient at finding the next meal, their caloric needs are met.

In other words, ravens are actually responsible for the creation of wolf packs.

All of this is a wintertime game.

During the summer months, like all other predators in this ecosystem, wolves spend more time going after the low hanging fruit and superabundant easy pickings in the form of ground squirrels. As the saying goes, it’s summertime, and the living’s easy.

But come winter, come the descent back into the throes of the Pleistocene, when ground squirrels and other small mammals are sound asleep in their hibernaculum, the menu changes to large animals such as elk and moose and bison. And if wolves want to stand a chance at surviving the RAVENous ravens, they must live and hunt in large social groups to survive.

Of all the many stories of the animals I am so fortunate to spend my life observing and photographing, it’s this relationship between ravens and wolves that fascinates me above all. The fact that ravens lead wolves to sick and injured animals is extraordinary enough in its own right. But add to this that ravens are actually the ones who eat the majority of the meat and are single handedly responsible for the social evolution of wolves simply blows my mind.