Wolves' return has had only small impact on deer populations in NE Washington, study shows

A new study shows that wolves in Washington state are not having much of an impact on white-tailed deer, one of their primary prey. In a paper published June 18, scientists report that the biggest factor shaping white-tailed deer populations in northeast Washington is the quality of habitat available. Cougars were second in their impact. Wolves were a distant third.


Newswise — Humans drove wolves to extinction in Washington state around the 1930s. Thanks to conservation efforts, by about 80 years later, wolves had returned — crossing first from the Canadian border into Washington around 2008 and later entering the state from Idaho. Since then, wolf numbers in Washington have been steadily growing, raising questions about what the return of this large predator species means for ecosystems and people alike.

In northeast Washington, where wolves have recovered most successfully, researchers from the University of Washington and the Washington Department of Fish and Wildlife tracked one of their primary prey — white-tailed deer — in part to see what impact wolf packs are having on deer populations. The answer? So far, wolves aren’t having as much of an impact on deer as other factors. In a paper published June 18 in Ecological Applications, the team reports that the biggest factors shaping white-tailed deer populations in northeast Washington are the quality of habitat available and a different, long-established large predator in the state: the cougar, also known as the mountain lion or puma.

Wolves were a distant third in their impact. “A big take-away from this study is that wolves are not returning to empty landscapes. These are places with humans and other carnivore species, like cougars, which will affect the impact that wolves can have,” said lead author Taylor Ganz , who conducted this research for her UW doctoral degree.