The survey found at least 51 wolves in nine packs in Washington state, including five successful breeding pairs. The 2011 study documented just 27 wolves, five wolf packs and three breeding pairs.
Wildlife wolf program director Nate Pamplin said the actual number of wolves is likely much higher, since lone wolves often go uncounted and those that roam Washington but do not den here are not included in the survey. Biologists already suspect there are two additional wolf packs in the state.
Using estimates of the average pack size in other western states, Pamplin said there could easily be as many as 100 wolves in Washington
"The survey shows that our state's wolf population is growing quickly," Pamplin said in a press release. "That growth appears to be the result of both natural reproduction and the continuing in-migration of wolves from Canada and neighboring states."
The recovery of wolves in Washington state is a heated topic. While many environmental groups hail the development, advocates for ranchers blame wolves for killing livestock. Several bills intended to improve wolf management are pending in the Legislature, including a tongue-in-cheek proposal to import wolves from rural parts of Eastern Washington to populous Western Washington.
A wolf pack is defined as two or more wolves traveling together. A successful breeding pair is defined as an adult male and female with at least two pups that survive until the end of the calendar year.
One of the nine packs represented in the survey is the infamous Wedge pack, which now has two confirmed members in northeastern Washington. Last summer, the Department of Fish and Wildlife killed most members of that pack to end a series of attacks on an area rancher's cattle that left at least six calves dead and 10 other animals injured.
Pamplin said biologists do not know whether the two wolves living near the Canadian border in Stevens County are members of the original Wedge pack or whether they are new arrivals from inside or outside the state.
"Either way, we were confident that wolves would repopulate that area," he said. "We really hope to prevent the kind of situation we faced with the Wedge pack last summer by working with ranchers to use non-lethal methods to protect their livestock."
The gray wolf is listed by the state as an endangered species throughout Washington and is federally listed as endangered in the western two-thirds of the state. Once common, wolves were eliminated in most western states during the past century because they preyed on livestock.
Under the state's Wolf Conservation and Management Plan, wolves can be removed from the state's endangered species list once 15 successful breeding pairs are documented for three consecutive years among three designated wolf-recovery regions.