HELENA, Mont. — Because it depends on heavy spring snowpack to excavate dens and safely raise its young near the top of mountain peaks high in the northern Rockies, the wolverine is on the front lines of battles over the effects of climate change.

There is less snow in the Rockies these days, and researchers forecast that in the coming decades, the wolverines in Idaho, Montana and Wyoming may disappear with the snowpack. Only about 300 of the animals are in the lower 48 states. In 2014, the United States Fish and Wildlife Service refused to list the animal for endangered species protection, calling the science inconclusive.

The debate over protection for the reclusive animal, the largest in the weasel family, has been going on for about 20 years, and it was revived this week by a federal court ruling here in Montana.

Chief Judge Dana L. Christensen of United States District Court for Montana on Monday rebuked the agency in a lengthy court decision, citing the “immense political pressure that was brought to bear” by Western states on the question of whether to list the wolverine, rather than relying on sound science. The states of Idaho, Montana and Wyoming, along with the petroleum industry and other groups, have opposed granting the wolverine the designation of a threatened species.