Colorado GMU 431 Mule Deer Hunting
Pitkin County, northwest Colorado · 220 sq mi
Based on the EASIEST unit-wide buck or either-sex hunt code available to adult Colorado residents in the 2026 primary draw — the lowest preference-point tier that drew reliably. Private-land-only and Ranching for Wildlife hunts are excluded because neither is a unit-wide public-land opportunity — NOT because the public cannot draw them. A private-land-only license requires the hunter's own permission to hunt private ground; a Ranching for Wildlife license is valid on the participating ranches enrolled in that program. They are separate systems. Other weapons, seasons and nonresident applicants can require substantially more points. The band is a floor, not a target: even the easiest qualifying hunt here sits in that range.
What hunting GMU 431 is like
GMU 431 is a 220-square-mile unit in the northwest region spanning from 6,800 feet to 14,300 feet, with a typical elevation near 10,400 feet. The terrain is steep and broken, with 36% of the unit steep and 10% rugged by area, offset by 16% gentle and 38% moderate slopes. Access to hunting ground is distributed across a range of elevations and exposures throughout the unit.
About 73% of the unit, roughly 160 square miles, is generally open to public hunting on National Forest and BLM land. The National Forest comprises 72% of the unit's total area, while BLM makes up 1.3%. Private land covers approximately 24% of the unit, and roughly 2.4% is unclassified ownership. Hunters planning to work public ground need to account for the presence of private inholdings and should verify access before heading into the field.
Mule deer occupy summer range across the full unit through early fall, then concentrate on about 10% of the unit during the winter period, with 3% mapped as a winter concentration layer where deer cluster. As fall progresses and temperatures drop—September highs average 58.5°F at mid-elevation, October highs average 47.8°F, and November highs average 37.5°F with snowfall reaching 27.7 inches—bucks shift through early migration and pre-rut phases before the primary rut peaks in mid-to-late November. Hunters should expect deer distribution to change as the season advances, with timing and extent influenced by weather and snow.
The unit offers multiple seasons across different weapons. Archery runs September 2–30 for either-sex hunting, falling in the velvet-shed phase when bucks are still in bachelor groups. Muzzleloader is September 12–20, also during velvet-shed conditions. Early rifle is a buck-only hunt September 12–20 in the same phase. The 2nd, 3rd, and 4th numbered rifle seasons run October 24 through November 22 (2nd Rifle: October 24–November 1; 3rd Rifle: November 7–15; 4th Rifle: November 18–22), spanning the transition from early migration through the primary rut. A private-land-only season runs October 24–November 15. Youth-only hunts (muzzleloader and rifle) exist for applicants under the specified age and are not open to general applicants. The unit draws as easy, often at zero preference points, for the most accessible buck or either-sex code available to adult Colorado residents. Hunter pressure remains low across the unit.
Terrain & elevation
- Elevation
- 6,800–14,300 ft, typically around 10,400 ft
- Steepness
- Rugged — mean slope 23.9°
- Slope breakdown
- 16% gentle · 38% moderate · 36% steep · 10% rugged
- Ground you can count on
- ~160 sq mi
Land & access
About 73% of GMU 431 is public land a hunter can count on — National Forest and BLM.
- National Forest72%
- BLM1%
- State Trust Land<1%
- Unclassified ownership2%
- Private24%
“Ownership unclassified” means the source dataset does not record an owner for that acreage. It is not known to be public or private.
Where mule deer live in the unit
Colorado Parks & Wildlife maps mule deer seasonal ranges statewide. This is how much of GMU 431 each range covers — the single best clue to whether mule deer are here in September, in November, or only passing through. The layers overlap, so they do not add to 100%.
- Summer Range100%used in summer
- Overall Range100%the full extent of range CPW maps for mule deer — near 100% on most units, and not a statement about when mule deer are present
- Winter Range10%used in winter
- Winter Concentration3%where mule deer bunch up in winter
- Migration Corridors<1%movement between ranges, not residence
Mule Deer seasons & weapons (2026)
| Season | Dates | Tags offered |
|---|---|---|
| Archery | September 2 – September 30 | Either-sex |
| Muzzleloader | September 12 – September 20 | Doe, Buck |
| 2nd Rifle | October 24 – November 1 | Doe, Buck |
| 3rd Rifle | November 7 – November 15 | Doe, Buck |
| 4th Rifle | November 18 – November 22 | Buck |
| Early Rifle | September 12 – September 20 | Buck |
| Youth only (Muzzleloader) | September 12 – September 20 | Doe |
| Youth only (Rifle) | October 24 – November 15 | Doe |
| Private-land only | October 24 – November 15 | Either-sex |
Dates span every hunt code of that type in this unit and can differ by code. Confirm the current brochure with Colorado Parks & Wildlife before applying.
Fall weather
- September — highs around 59°F, lows around 35°F, about 0.5 in of snow (mid-elevation normals)
- October — highs around 48°F, lows around 26°F, about 9.2 in of snow (mid-elevation normals)
- November — highs around 38°F, lows around 15°F, about 27.7 in of snow (mid-elevation normals)
GMU 431 mule deer hunting FAQ
Is this unit realistic for an applicant with no preference points?
Yes. The unit draws as easy for the most accessible buck or either-sex code available to adult Colorado residents, and preference points are often zero for those hunts. Other weapons, seasons, and nonresident applicants can require substantially more points. An applicant with no points should verify which specific hunt tier qualifies at zero before submitting.
How much public land can a hunter actually count on hunting here?
About 73% of the unit, or roughly 160 square miles, is generally open to public hunting on National Forest and BLM land. Private ground covers 24% of the unit, and an additional 2.4% is unclassified ownership. Hunters should scout beforehand, as roads, trailheads, seasonal closures, and private inholdings all affect where and how ground can be accessed.
Does this unit favor early or late season hunting?
Early hunts (archery and muzzleloader in early September, plus early rifle through September 20) occur during the velvet-shed phase when bucks are still grouped in bachelor patterns. Later rifle seasons (October 24 through November 22) span the transition into pre-rut and primary-rut phases, when buck behavior shifts toward seeking does and movement increases. The choice depends on whether a hunter prefers predictable bachelor-phase hunting or the more variable rut window.
How does terrain affect what a hunter on foot can cover?
Steep and broken ground makes up the majority of the unit, with 36% steep and 10% rugged terrain. Moderate slopes cover 38% and gentle slopes 16%, so terrain varies significantly by location. Hunters should expect mixed conditions and plan accordingly for the elevation span, which ranges from 6,800 to 14,300 feet.
Where should a hunter expect deer to be as fall progresses?
Early in the season, mule deer occupy summer range across the full unit. As fall advances and temperatures drop—especially with November snowfall averaging 27.7 inches at mid-elevation—deer consolidate onto a smaller portion of ground. About 10% of the unit holds winter range, with 3% mapped as a winter concentration layer where deer cluster during that period. Timing and extent of the consolidation vary with weather and snow.
What draws this unit as and how does that compare to other elk opportunities?
This is a mule deer unit, not an elk unit. The unit draws as easy for the most accessible buck or either-sex code available to adult Colorado residents, often at zero preference points. However, the unit holds at least one premium buck season that requires substantially more preference points than the easiest hunts.
Data sources & methodology
- Colorado Parks & Wildlife — Big Game hunting — seasons, weapons, hunt codes and license types
- CPW — Primary Draw rules — how preference points and the hybrid draw work
- CPW — Deer statistics, draw recap and Drawn Out At reports — the point levels behind the draw-difficulty bands
- CPW — Secondary Draw — licenses remaining after the primary draw
- CPW — Maps and GIS (Species Activity Mapping) — mule deer seasonal range
- CPW — State Trust Land Finder — which State Trust acreage is enrolled and open to public hunting
- Federal and state land-ownership datasets — land ownership and access
- NOAA climate normals — fall weather
Draw difficulty is a qualitative band, not published odds — the note under the summary above states exactly which hunt code it describes. Land shares are separate, non-overlapping categories: publicly owned is not the same as open to hunting, and State Trust Land is huntable only where CPW has enrolled it. Unit data last updated August 31, 2026.