How humans break up wolf packs

A new study explores how packs change when activities like hunting and car accidents kill wolves.

 

A wolf stands in the road at Yellowstone National Park. Data collected by researchers shows just over a third of the collared wolves living primarily in five protected national parks died of human-causes.
Jacob W. Frank/National Park Service

Packs are to wolves as families are to humans: They’re the species’ most essential social structure. The dynamics of a wolf pack — who its leaders are, how the members raise pups, how they hunt their prey, and how they respond to threats — determine the group’s survival.  

But so far, the majority of wolf research has focused on the species’ population as a whole, rather than individual packs. Wolf populations tend to stay pretty steady despite human-caused mortality. But we also know that some wolves avoid busy roads, that heavily hunted wolves have high stress hormones, and that human development fractures wolf habitat. This gap in understanding led a group of National Park Service employees and biologists to ask: How does human activity alter individual wolf packs?

That question inspired a new study, recently published in the journal Frontiers in Ecology and Environment. The research analyzed how human-caused deaths — from hunting and poaching to car accidents and research captures — have affected nearly 193 wolf packs in five national parks and preserves. The researchers used data collected in those parks between the late 1980s and the present. Just over a third of the collared wolves living primarily in those protected national parks died of human-causes, and those deaths had negative consequences for some of the packs.

Packs affected by human-caused wolf deaths were less likely to reproduce, while losing a pack leader decreased the chances that the pack stayed together or had pups the next year. The researchers also found that pack size matters: Packs that were smaller to begin with were more likely to dissolve, while bigger packs proved more resilient. “If human families have to deal with the death of family members — like two in a row, or the leader of the family — that would be much more disruptive and harder to get through,” said lead author Kira Cassidy, a research associate with the National Park Service’s Yellowstone Wolf Project. Larger packs have more members waiting in the wings to take over any responsibilities and duties that a sudden void in the pack may leave unfilled.

Packs affected by human-caused wolf deaths were less likely to reproduce, while losing a pack leader decreased the chances that the pack stayed together or had pups the next year. 

Cassidy said she recently observed this in Yellowstone. In late 2021, before hunting season, the park’s Junction Butte Pack had 28 members, making it a relatively large group. Hunters outside the park legally killed eight wolves, all of them young. The group rebounded quickly; In the spring of 2022, the pack had four litters of pups, and now has 25 members. A smaller pack may have broken up and dispersed, or not reproduced to that extent. “Socially, they’re fragile,” said co-author Doug Smith, the recently retired Yellowstone senior wolf biologist.

The study shows the importance of tracking wolf packs, rather than just population numbers, said Mark Hebblewhite, a University of Montana professor not involved in the research who studies wolves and ungulates. This new understanding shows wildlife managers that human boundaries can’t always protect wildlife. “This paper recognizes that national park animals like wolves and bison are vulnerable to harvest when they leave the park,” Hebblewhite said. “They spent all summer seeing hundreds of cars and thousands of people, and those people don’t do anything bad to them. And then they leave the park, walk right in front of an outfitter camp, and get hammered by somebody shooting them.”

The authors hope the study spurs more collaboration between national parks and neighboring states to limit humans’ effect on wolves living near the edge of protected areas. “This paper may be useful not only to point out how important packs are, (but also) how important it is for us to understand how we are responsible for impacting another species,” Cassidy said. “I’m pretty proud that this study gives people the information to say, ‘This is our impact.’”

Kylie Mohr is an editorial fellow for High Country News writing from Montana. Email her at [email protected] or submit a letter to the editor. See our letters to the editor policy

High Country News Classifieds
  • 2023 SEASONAL AND FULL-TIME POSITIONS AVAILABLE!
    Advance your career while completing vital forest and watershed restoration in wild and scenic northern Sierra!
  • CONSERVATION EASEMENT PROGRAM MANAGER
    We are seeking a dedicated natural resources professional to lead FRLT's Conservation Easement Stewardship Program. This position is responsible for maintaining professional working relationships with...
  • PUBLIC PROGRAMS MANAGER
    We are looking for a hands-on leader to bring our public programs to life in Sierra Valley and across the Watershed. This role offers a...
  • MATADOR RANCH MANAGER
    The Matador Ranch Manager directs operations, communication, and maintenance for TNC Montana's Matador Ranch preserve with a focus on ecological management and restoration, grazing management,...
  • EXECUTIVE DIRECTOR - THRIVE HOOD RIVER (OREGON)
    Thrive Hood River (Oregon) is looking for a collaborative leader who cares deeply about Hood River's wild places, farmland and the quality of life in...
  • NORTHERN NEW MEXICO PROJECT MANAGER
    Seeking qualified Northern New Mexico Project Manager to provide expertise, leadership and support to the organization by planning, cultivating, implementing and managing land conservation activities....
  • NORTH FORK RECREATION DISTRICT ADMINISTRATOR
    The NFPPRD District Administrator provides leadership and managerial services associated with the Recreation District. Facilities include a seasonal pool, ballfields, bike trails, tennis/pickleball and skateboarding....
  • EXECUTIVE DIRECTOR, BADLANDS CONSERVATION ALLIANCE
    The Executive Director of the Badlands Conservation Alliance (BCA) builds and leads a premiere North Dakota advocacy group that serves to protect the ecology of...
  • CLIMATE FELLOW
    Application deadline: Monday, March 6th, 2023, at 5 p.m. MST. Anticipated start date: May 15, 2023 About the position Are you ready to craft an...
  • RISING LEADERS MANAGER
    Application deadline: Monday, March 27, 2023, at 5 p.m. MST Anticipated start date: May 22 or May 30, 2023 About the position Do you want...
  • SENIOR SPECIALIST, LANDSCAPE CONNECTIVITY YELLOWSTONE TO YUKON CONSERVATION INITIATIVE
    About the Organization Yellowstone to Yukon Conservation Initiative (Y2Y) is a joint Canada-U.S. not-for-profit organization with a mission to connect and protect wildlife habitat from...
  • VIRGINIA SPENCER DAVIS FELLOWSHIP
    High Country News, an award-winning magazine covering the communities and environment of the Western United States, seeks applicants for a Virginia Spencer Davis fellow. The...
  • GRANTS MANAGER
    The Grants Manager is a passionate information manager, fundraiser, and communicator versed in government and foundation grant and cooperative agreement writing and management, specifically to...
  • COMMUNICATIONS DIRECTOR
    The Communications Director is a passionate communications professional versed in conservation and regenerative agriculture, as well as nonprofit communications and data management across several program...
  • EDUCATION AND OUTREACH PROGRAM DIRECTOR
    The Education and Outreach Director is a people-oriented facilitator, communications wizard, and team leader who has experience designing, managing, and fundraising for land based educational...
  • ADOBE HOME FOR SALE
    Restored traditional adobe home in No. New Mexico on 1+ acre site, irrigation water, separate large shop/studio. Please email for photos/full description.
  • HIGH COUNTRY NEWS EDITORIAL INTERNS
    High Country News, an award-winning magazine covering the communities and environment of the Western United States, is looking for its next cohort of editorial interns....
  • DEVELOPMENT PROGRAM SPECIALIST
    hat We Can Achieve Together: If you are a detailed individual that takes pride in your accuracy, this position may be the perfect opportunity for...
  • ENVIRONMENTAL AND CONSTRUCTION GEOPHYSICS
    We characterize contaminated sites, identify buried drums, tanks, debris and also locate groundwater.
  • WESTERN NATIVE SEED
    Native plant seeds for the Western US. Trees, shrubs, grasses, wildflowers and regional mixes. Call or email for free price list. 719-942-3935. [email protected] or visit...