Unit 131 takes in Las Animas and southern Otero County country east of Trinidad along the Purgatoire River drainage and the Picketwire Canyonlands of the Comanche Grassland's Timpas Unit. Elevations 4,500 to 6,000 feet. The terrain layers from open shortgrass and sandsage prairie on the upper benches into the dramatic canyon-and-rim country where the Purgatoire and its tributaries have cut deep into volcanic and sandstone bedrock. The Picketwire Canyon itself is one of Colorado's true geological surprises—deep, steep-walled, with cottonwood gallery bottoms, juniper-studded rims, and a famous dinosaur trackway accessible only by foot, mountain bike, or guided wagon tour from the trailhead off CR-2185. Mule deer hold the canyon rims and juniper benches in real numbers and grow big where access is genuinely tough; pronghorn cover the open uplands; wild turkey haunt the cottonwood bottoms; the rare elk has been showing up. The Timpas Unit of Comanche Grassland and the Picketwire trailheads provide the headline public ground—tens of thousands of acres, but motorized access is restricted in the canyon proper, so plan to walk in or take a bike. US-350 (the historic Santa Fe Trail corridor) runs from La Junta southwest toward Trinidad and is the paved spine; FS roads and county routes branch off into the Grassland. The rest of the unit is deeded private ranchland. Trinidad has full services—gas, motels, processors, hospital. Cell service is fair on US-350 and gone in the canyons. Mule deer in the Picketwire is one of the most overlooked DIY public-land hunts in eastern Colorado—the country looks like it shouldn't produce big bucks, and it absolutely does for hunters who do the boot-leather work.