The greater sage-grouse is the largest grouse in North America and one of the most ecologically embattled. Adults are obligate sagebrush specialists — they eat sage in winter, nest under sage in spring, and lek-display on bare ground inside sage country every March. No sagebrush, no sage-grouse. It's that direct.
Continental populations have fallen by roughly 80% since 1965 based on long-term lek-count data. The drivers are well-documented: conversion of sagebrush steppe to agriculture and energy development, invasive cheatgrass and the larger, hotter wildfires it carries, conifer encroachment into sage country, fragmentation by roads and fences, and on top of all of that, West Nile virus mortality in some populations. The species has been petitioned for federal listing under the Endangered Species Act multiple times. As of this writing it is not federally listed, but conservation status is closely tracked and the regulatory picture changes.
A limited number of western states — Colorado, Wyoming, Montana, Nevada, Idaho, Oregon, and a few others — still operate tightly regulated sage-grouse seasons under conservation-hunting frameworks: short seasons, low bag limits, permit-only access in many units, and harvest reporting. Read the state agency page carefully. In several historical states, sage-grouse hunting is closed entirely. Anyone hunting this species owes the bird a deep look at the habitat picture before they pick up the shotgun.