Any decline in the population of sage grouse, interestingly enough, is inversely proportional to the increase in the coyote population. When active fed programs aimed at coyote population control were stopped, their numbers ballooned. Grouse are on the menu. Losses of sheep, calves, and other small domestic stock are back up, too.
It is the nature of unmanaged populations to go through boom/bust cycles. When there are few predators, the prey species bloom. The predators have plenty to eat and multiply rapidly. When the predators become numerous, they run out of prey and starve. At that time, the prey population rebounds. And so on.
The decision to place a species on the endangered list should not be made based on the current phase of the predator/prey cycle. And data supporting (or not) the decision to list a species really should be public.
I suspect the endangered species act is used inappropriately more times than not, with the goal to prevent land use.
I bet wolves would chow down on grouse, too, just as soon as they are done shredding the elk.