Unit 43A (Dome Rock Mountains and Trigo Peaks)

The primary concentration of bighorn in 43A is the north end of the Dome Rock Mountains, on the north side of Interstate 10. A second herd lives south of the Dome Rocks in the North and South Trigo Peaks, on the Yuma Proving Ground.

The boundary that is not marked

Take this seriously before anything else. The Dome Rock country is managed almost exclusively by BLM, but the Colorado River Indian Tribes reservation boundary lies to the northwest and is not clearly marked. La Paz Mountain lies mostly inside the reservation. Load that boundary into your GPS; you will not see it on the ground.

Into the north Dome Rocks

Access is through Quartzsite. From Main Street take Kofa Avenue, opposite the Pilot gas station, and run north about 1.5 miles until a road leads off left into the desert. Numerous wildcat roads branch off — stay on the main one. Four miles in you start climbing into Middle Camp Mountain at Marquetta Pass. Access through Marquetta has become limited because a small parcel of private property has been fenced and gated across the road.

The alternatives to Marquetta

Diablo Pass, just east of Marquetta, gets you into the range — a very rough road needing four-wheel drive. Marquetta can also be reached from the north through Boyer Gap: take the dirt road west at milepost 114 off Highway 95 north of Quartzsite, continue west out of Tyson Wash to Boyer Gap, then take roads south to Marquetta. Those roads are very rough, need four-wheel drive, and the trip takes a few hours. There's a lot of active private mining through here — don't disturb operations or property.

The Trigo Peaks

Take Highway 95 south from Quartzsite to milepost 82, the Cibola Road, and travel west about 30 miles to the base of the South Trigo Peaks. Several unmarked roads run back around the peaks; the agency suggests buying a BLM map to find them. Once you're there, expect legwork — hiking to the tops of the peaks and glassing is how this country is hunted.

These sheep move

The guide makes the point explicitly: bighorn here are migratory and will shift from one mountain range to another, so make several trips to locate animals before the hunt begins. One scouting weekend is not enough in 43A.

Rifle success on these tags runs about 75 percent. The guide says pre-hunt scouting is very important here, and it gives a specific reason rather than a generic one.

Scout more than once

These sheep migrate between ranges. A ram located in September may be in a different mountain in December. So plan several trips rather than one, and build a picture of which ranges hold animals at which time of year rather than a single pin.

Put the reservation line in your GPS

The CRIT boundary northwest of the Dome Rocks is unmarked on the ground and La Paz Mountain is mostly inside it. That's the single highest-consequence navigation problem on this unit. Load it, and check it before you glass a new face.

Expect to hike the Trigo Peaks

Once you've reached the base off Cibola Road, the hunt is legwork: climb a peak, glass from the top, and work the country below and around you. Buy the BLM map for the unmarked roads around the peaks, and remember this ground is Yuma Proving Ground — confirm access requirements before you go.

Prepare the vehicle, not just the rifle

Diablo Pass and the Boyer Gap route are described as very rough and need four-wheel drive; the Boyer Gap approach takes a few hours each way. Two spares, recovery gear, and more water than the day needs. The gate across Marquetta Pass is private property — don't force it, use Diablo or Boyer Gap.

Glass from the base, approach sideways

Ten or 20 power from the bottom before climbing, stay in the lower two-thirds once you're up, and stop often to sit, glass and listen. Move indirectly and avoid eye contact when you close — curious sheep will often let you come.

Mining country manners

There's a lot of active private mining in the Dome Rocks. Keep clear of operations and equipment, don't block roads, and treat the gates as what they are. Access here has already narrowed once.