GMU 851 GMU 851 — Costilla/Las Animas Co.
Rugged, hard-private mountain unit from oak-brush foothills to Culebra Peak's 14ers, with limited-draw elk and a sliver of public ground
South-central Colorado — Sangre de Cristo high country west of Trinidad · Last reviewed 2026-07-12
Area
439
sq mi
Public land
10%
approx.
Elevation
6,025–14,049
feet
Motorized
limited
access
Overview
GMU 851 climbs from the piñon-oak foothills west of Trinidad up the east face of the Sangre de Cristo Range to the crest at Culebra Peak (14,047 ft), bounded by I-25 on the east, the Purgatoire River drainage on the north, New Mexico on the south, and the Sangre de Cristo divide on the west. It is heavily forested mountain country — scrub-oak breaks, aspen and mixed conifer, and sharp canyons rising to alpine tundra. Elk lead the unit in harvest but success runs modest because the great majority of the ground is deeded ranchland (Culebra/Cielo Vista and neighboring holdings), and all big game here is limited-draw — this is not over-the-counter elk country. Drawing a tag and getting on huntable ground are two separate problems.
Terrain
East flank of the Sangre de Cristo Range — scrub-oak and juniper foothills and canyon breaks climbing through aspen and dark timber to steep alpine peaks along the crest at Culebra.
Cover: Roughly evergreen forest over half the unit, with big-sagebrush and Gambel oak shrublands on the lower breaks, grassland parks, aspen and mixed conifer on the mid-slopes, and alpine tundra above timberline.
Landmarks: Culebra Peak (14,047 ft) · Purgatoire River canyons · Bosque del Oso State Wildlife Area · Sangre de Cristo crest / divide · scrub-oak foothills above Trinidad
Access
There is very little public land in 851. The main huntable public ground is Bosque del Oso SWA on the north side of the unit, plus small strips of national forest near the crest and along the north boundary. The Sangre de Cristo high country and the best mid-elevation elk timber sit almost entirely behind large private ranches (Culebra/Cielo Vista and neighbors). State Trust sections are generally closed unless enrolled in CPW's Public Access Program. Realistic public hunting centers on Bosque del Oso and demands early scouting; many tags here are hunted through ranch access, leases, or landowner programs.
Managers: private ranch, Bosque del Oso State Wildlife Area (CPW), San Isabel / Carson National Forest (small tracts on the north and crest), Colorado State Trust Land (generally closed unless in CPW Public Access Program)
Access points: I-25 / Trinidad and CO-12 (Highway of Legends) corridor · Bosque del Oso SWA access off CO-12 · county and forest roads on the north boundary · Purgatoire drainage road network
Species notes
Rocky Mountain Elk
common qualityThe unit's top-harvested big game. Elk hold in the aspen and dark timber of the Sangre de Cristo mid-slopes and drop to feed in the oak breaks and parks. Limited-draw only — no OTC — and modest success reflects how much of the herd lives on inaccessible private ground rather than any shortage of animals; ranch-managed bulls can be very good.
- →Hunt aspen benches and timbered draws on the mid-slopes where elk bed
- →Glass oak-brush breaks and grassy parks at first and last light
- →During the rut, work timbered canyon heads with calling
- →Pin down Bosque del Oso and forest access first — access is the whole game here
Mule Deer
common qualityMule deer use the oak-brush foothills, juniper breaks, and canyon country throughout the unit, with bucks moving into higher timber and rims. Limited-draw. Better-than-average success reflects good habitat, though private ownership dictates where you can actually hunt.
- →Glass oak brush and juniper edges at dawn and dusk
- →Bucks hold in canyon-head thickets and shaded rims through midday
- →Hunt the transition between foothill breaks and higher timber
- →Concentrate on Bosque del Oso and any accessible forest edges
Pronghorn
limited opportunityA small number of pronghorn use the open grassland benches and sage flats on the lower, eastern side of the unit near the I-25 corridor. Harvest is tiny — this is a mountain unit with only marginal antelope range on its fringe.
- →Glass the open lower benches and sage flats east toward the interstate
- →Hunt near water in dry early-season conditions
- →Verify huntable ground before committing — most open flats are private
Black Bear
common opportunityBlack bears are well distributed through the oak-brush, aspen, and timber, drawing on acorn and berry crops in the foothill breaks. Good habitat, though access again limits where you can hunt them.
- →Focus on oak-brush and berry pockets when mast is on
- →Work aspen and drainage edges in the mornings and evenings
- →Glass south-facing scrub-oak slopes in early fall
Moose
transient opportunityThe Sangre de Cristo range holds a small, expanding moose population, and stray animals occur in the willow drainages and high basins of 851. Numbers are low and any hunting is a rare limited draw.
- →Look in willow-choked drainage bottoms and beaver complexes
- →Check high timbered basins near the crest
- →Treat as an incidental, low-density presence
Pro tips
- →Treat access, not the tag, as the hard problem — Bosque del Oso SWA is the anchor public tract, scout it early
- →This is a limited-draw, not OTC, unit — build points and plan the draw accordingly
- →State Trust sections are generally closed; verify any parcel is truly open before hunting
- →Elk shift with snow — early seasons hunt higher timber, later hunts follow animals down to private edges
- →Wet or snowy forest and clay roads get impassable fast at elevation
Watch out for
- !Overwhelmingly private land — large ranches lock up most elk and deer range
- !State Trust Land generally closed to hunting unless in CPW's Public Access Program
- !Steep, rugged Sangre de Cristo terrain with real avalanche and exposure hazard up high
- !Early snow can close access and strand vehicles
- !Wildfire risk and possible closures in dry oak-brush and timber country
Logistics
Trinidad on I-25 is the hub for fuel, lodging, groceries, and processing, with CO-12 (the Highway of Legends) the main artery west into the unit. Backcountry travel is on forest and ranch roads that turn slick when wet and can hold early snow at elevation — carry recovery gear and chains. Cell coverage fades quickly off the interstate and CO-12 corridor.
Nearest towns: Trinidad, Aguilar, Stonewall, Raton, NM (services, ~30 min south)
Seasons & regulations
This page carries no season dates or regulations. Get current rules from the official Colorado sources:
Research sources: CPW Big Game Hunting Statistics · CPW GMU boundary descriptions · USFS San Isabel National Forest
FAQ
- How big is GMU 851 in Colorado?
- GMU 851 (GMU 851 — Costilla/Las Animas Co.) covers about 439 square miles, ranging from roughly 6,025 to 14,049 feet in elevation. Area is computed from the unit boundary polygon.
- How much public land is in GMU 851?
- Approximately 10% of the unit is public land. Primary managers: private ranch, Bosque del Oso State Wildlife Area (CPW), San Isabel / Carson National Forest (small tracts on the north and crest), Colorado State Trust Land (generally closed unless in CPW Public Access Program). Always verify ownership boundaries on the ground.
- What species does the catalog list for GMU 851?
- Rocky Mountain Elk, Mule Deer, Pronghorn, Black Bear, Moose. For seasons, tags, and regulations, use the official Colorado agency resources linked on this page — this page carries no regulatory information.
Put GMU 851 on your map.
Boundary lines, public/private ownership, topo, and offline maps for this unit — in Baseline Maps, free for 14 days.