FYI.

This story is over 5 years old.

Tech

The Rocky Mountain Wolf Population Declined After Losing Endangered Species Protection

801 wolves were killed last year.
A gray wolf chilling in the snow, by Tracy Brooks/Mission Wolf/USFWS

In 2012, after an incredible recovery, gray wolves in the Rocky Mountain region were taken off of the US Endangered Species Act, following the delisting of wolves in the Great Lakes region in 2011. That decision meant Rocky Mountain wolves, including those in Montana, Idaho, and Wyoming, could be hunted if their home states decided to allow it. Now, in the first year-long population report since hunting started, the Fish and Wildlife Service (FWS) has announced that the wolf population in the Rockies has declined seven percent since 2011.

This is the first decline in the Rocky Mountain wolf population, known as the Northern Rocky Mountain Distinct Population Segment, since they were reintroduced in the region in 1995, and it was expected. The 2012 count for the region, which along with the three aforementioned states also includes the eastern portions of Washington and Oregon and north-central Utah, stood at 1,674 individuals, down from 1,804 in 2011. That's not a huge loss after a year's worth of hunting, especially after projections put the sustainable floor of the population at around 1,000 individuals.

Advertisement

That population level, which Fish and Wildlife agreed upon with state management agencies, may still be reached at some point in the future. Mike Jimenez, wolf management and science coordinator for Fish and Wildlife, told the LA Times that the decline came as no surprise. “The states are very carefully bringing the population down," he said.

The range of the Northern Rocky Mountain wolf population, via FWS. Click to enlarge.

In total, 570 wolves were killed by hunting or trapping in 2012 across Montana, Idaho, and Wyoming, while an additional 231 "problem" wolves were killed because they had either attacked or posed a threat to livestock. (According to FWS, "total confirmed depredations by wolves in 2012 included 194 cattle, 470 sheep, six dogs, three horses, and one llama.")

All told, that's 801 individuals killed, including some very high profile collared wolves in Yellowstone. But assuming the data are correct, the total wolf population only declined by 130 in the region. That suggests that the region's wolf population is healthily reproducing, although it'll take more of a year's worth of data to get any long-term idea of how healthy the population is.

One theoretical example I can think of is that the 800 adult wolves killed were replaced by 670 pups (wolf litters average between five and six individuals, and there are 111 breeding pairs in the region, so 670 pups in 2012 isn't a crazy number), in order to get a total decline of just 130 or so.

Advertisement

But those pups have less of a chance of becoming healthy adult wolves than would a wolf that was already an adult. In other words, while those 670 pups make the population decline look fairly small this year, they're not all going to survive until adulthood when they can start reproducing again.

So in total numbers, an increase of 670 pups combined with the loss of 800 adults is only a difference of 130. But it will take time for those pups to mature to breeding age, during which the adult they replaced could have been producing more pups. As the years go on, the actual effects of the wolf hunts on its population may be greater than this year's decline suggests.

That theoretical problem does not appear to be as dire in actuality. According to FWS, the number of breeding pairs dropped from 111 to 103. If that's true, the reproductive ability of the total wolf population hasn't been impacted as much as the 801 dead wolves might suggest. Additionally, the number of total wolf packs rose, which could mean that more young wolves are splintering off to start their own packs/families, but that's semi-educated, semi-hopeful speculation on my part.

In any case, from a management standpoint, a 7 percent loss in the first year of hunts isn't horrible. From an ecological standpoint, losing predators like wolves can have problematic cascade effects, but again, this first year isn't a disaster. FWS and state management officials have to balance the needs/concerns of ranchers while maintaining a healthy natural population of wolves, and the population remains a ways away from that 1,000 individual floor. But while this year wasn't disastrous, it's the long term that's more important. Losing seven percent of the population every year will quickly add up.

@derektmead