Wolf Packs Suffer When Humans Kill Their Leaders

Wolves are amazing and magnificent carnivores. They are highly social, pack-living animals whose numbers have been decimated globally because of their predatory ways.

While it's been known that human intrusions into their lives can affect their behavior, a new, landmark study–called "one of the most important papers to come out of Yellowstone in his 28 years with the park" by Doug Smith, one of the world's leading wolf experts who led Yellowstone's wolf reintroduction for many years–shows that when people kill wolves their pack becomes less stable and can disband and cease to exist.¹

Details of this seminal research can be found in an open-access essay by Kira Cassidy, a research associate with the Yellowstone Wolf Project, and her colleagues, called "Human-Caused Mortality Triggers Pack Instability in Gray Wolves."^2,3 Not only do groups suffer, but individuals do as well.

Source: patrice schoefolt/Pexels.

The database for this new study is massive: the researchers analyzed more than 118 years of cumulative data from five national parks, all within the historical and current gray wolf range in the United States. The parks included Yellowstone, Grand Teton, Voyageurs National Parks, Denali National Park Preserve, and Yukon-Charley Rivers National Preserve.

Data from 193 packs (with 2 to 37 wolves) over 864 pack years were analyzed and included 978 wolf mortalities from 1986 to 2021. Each year, an average of 5.3 percent of each pack died from a human-related cause.

Here is a brief summary of what the researchers learned.

Human-caused mortality accounted for 36 percent of collared wolf mortalities and had a detrimental effect on both pack persistence and reproduction. The human-caused mortality of any wolf decreased the predicted odds of pack persistence to the end of the biological year by 27 percent and reproduction the following year by 22 percent.

Packs with no reported human-caused mortalities persisted to the end of the biological year 91.6 percent of the time, while packs that experienced at least one reported human-caused mortality persisted 76.3 percent of the time."

Packs with no reported human-caused mortalities reproduced the following year 79.0 percent of the time, whereas packs with at least one reported human-caused mortality reproduced the following year only 65.6 percent of the time.

Larger packs were better to recover from human-caused intrusions than smaller packs.

Why this study is so important.

Paul Paquet, Senior Scientist at the Raincoast Conservation Foundation in Canada and a wolf expert, noted,

The foundation of good conservation and management of wildlife is science buttressed by persuasive moral arguments and ethics. Accordingly, this seminal study has important implications regarding the conservation of gray wolves and the contentious public debate surrounding their future.¹

All in all, while it's known that wolf packs come and go and wolves leave their groups for a wide variety of reasons, human intrusions increase the frequency of occurrence of pack instability and disbandment and reduce reproductive output so that fewer wolf children are produced. It's not known how removing wolves from packs in one location and moving them to another location, as is done in reintroduction or repatriation studies, influences the packs from which wolves were removed, and it is extremely important to know a lot more about the effects of these types of human intrusions on packs and on the well-being of individual wolves and other species who are affected by these experiments.⁴

Sentience, emotions, and conservation. Wolves, like dogs, are sentient, feeling animals, and it's also important to consider what they're thinking and feeling during translocation efforts, from the time they're pursued and trapped to when they're transferred and then put out in a new, unfamiliar place where they're not always welcomed.⁵ Welcomed or not, I'm sure they they'd be feeling incredibly scared and stressed. It's also perfectly okay to factor in our own feelings and the principles of compassionate conservation into decisions about what we're doing to wolves and other animals–their and our emotions matter.⁶ For more discussion of the daunting practical on-the-ground aspects and the serious ethical issues involved in doing these sorts of projects, many of which do not meet the eye, see "The Hidden Slippery Slopes of Animal Reintroduction Programs."

While common sense tells us that we all "know" that humans can seriously disrupt the natural behavior of many wild animals, it's essential to have data such as those reported in this study. The researchers call for more analyses of the ways in which humans influence the behavior and mortality of wolves, along with more science-based management plans. These include how to minimize the effects of people who understandably want to see these magnificent social beings in their natural homes.

Philosopher Martha Nussbaum has argued that justice for animals means the freedom to do what comes naturally. I agree, and when animals can do what they've evolved to do in the presence of humans, it's a win-win for all–the humans get to see these wild animals in action as they would behave when the humans aren't around.

I look forward to future studies on other animals who people want to observe so that their desires can be fulfilled and so that they hopefully will come to respect and appreciate these amazing nonhumans and at the same time, the well-being of individual animals and their groups will be closely and vigorously protected so that they can continue to live their natural lives and do what they're supposed to do as members of their respective species.