Jun 15
Lamar Canyon Pack

Male Gray Wolves Protect Family Members from Rival Packs

Since their reintroduction in 1995-96, Yellowstone National Park has become an important place to study wolf behavior and the species’ impact on the ecosystem. Kira Cassidy—a research associate with the Yellowstone Wolf Project—shares her newest findings on male wolf behavior in Yellowstone, and how it connects to the social interactions of humans.

My mom makes a delicious venison chili. But at about seven years old I decided that lima beans were my enemy and by association kidney beans were highly suspect. Something had to be done and good thing my younger sister loved beans. We swapped spoonfuls back and forth until she had a bowl full of beans and mine was mostly venison and tomatoes. Decent problem-solving and teamwork for a pair of little curly-haired kids intent on avoiding slightly unsavory foods.

Nowadays it is clear that cooperation and teamwork are at the center of success in everything from business to sports, innovation to education (and avoiding undesirable legumes?). But this isn’t a new phenomenon; for millennia humans lived in small groups of hunter-gatherers where each person had certain responsibilities—hunt large game, tend the fires, make weapons, raise the children, protect the group from invaders, train the dogs and horses. The division of labor eventually morphed into distinctive occupations as societies became larger. But teamwork doesn’t require a Homo sapiens-sized brain, or bipedalism, or a younger sister who doesn’t yet hate lima beans; a few other species use the same strategy.

8 Mile pack pupsGray wolves have figured out how to succeed by sharing the group’s tasks and responsibilities amongst all pack members. The dominant, breeding females choose den sites that are safe for the new pups and well-placed to be the pack’s summer hub of activity. Wolves between one and three years old are the fast hunters, selecting prey and tiring it out while the large adult males use their weight to bring down ungulates five to ten times larger than any one of them.

Recent studies in Yellowstone have found that male wolves specialize in protecting their own family by fighting off rival packs. Males are about 20% larger than females in size so they are physically built for the task, too—biting, pushing, grappling, sometimes killing their enemies. Male wolves do this to eliminate competition and also to protect their family. This may be why older males become even more aggressive—breeding opportunities are dwindling and they’ve put a lot of effort into raising and looking after their current offspring. Some old male wolves have many family members to protect, such as the former alpha male of the Mollie’s pack who, at six and a half years old, lived in a pack with his mate and their 16 offspring.

Living in such a large pack can also affect an individual wolf’s behavior. A wolf is more likely to chase a rival if they know they have strength in numbers. But females are still more conservative, only chasing if their pack outnumbers the enemy by 1.5 wolves. A male will still chase the rivals even if he’s outnumbered by 3.5 wolves.

Lamar Canyon PackCooperative, family-living carnivores, like gray wolves, are fairly rare. Cooperative siblings sharing vegetables may be particularly uncommon…. But it’s no surprise that gray wolves and humans are so alike in their behavior. They live in family units, they cooperate to accomplish complex goals and everyone is safer and healthier because of teamwork. Specific tasks are taken on by certain family members, just like a male gray wolf will protect the pack from rival groups. It is, after all, a responsibility that evolution has written into his DNA for tens of thousands of years. Protect the family with your life, family lives, genes are passed on, repeat.

This research, using 16 years of data from Yellowstone National Park’s gray wolves, was published in 2017 in Behavioral Processes under the title “Sexually dimorphic aggression indicates male gray wolves specialize in pack defense against conspecific groups.” Contact Kira for a copy of the article at [email protected].

Yellowstone Forever is a proud contributor to the Yellowstone Wolf Project, supporting key elements of the project’s research and monitoring activities including collaring and aerial monitoring. Learn more about the project and how you can get involved.

8 Mile Pack