If you go

Highlights: Raptors, prairie dogs, wetlands, views, working ranch

Distance: 3.8 miles one-way

Difficulty: Easy to moderate

Access: Leave one car at Boulder Valley Ranch Trailhead on Longhorn Road, 1 mile east of U.S. 36 and about 2 miles north of the intersection of U.S. 36 and North Broadway. Leave another car at Eagle Trailhead, on the west side of 51st Street, half a mile north of the entrance gate to Boulder Reservoir.

Snow splotches the rolling tan grasslands at Boulder Valley Ranch now.

But one summer-like day, a small rattlesnake slithered across the trail to disappear into the brush at the intersection of Eagle and Sage trails. We like to think a nearby hibernaculum may be protecting a cluster of rattlers curled together under the frozen ground.

Many prairie dogs remain active all winter providing food for hawks, golden and bald eagles, and coyotes. Prairie dog burrows also provide dens for many creatures — including cottontails and rattlesnakes.

Eagle and Cobalt trails connect 51st Street and Boulder Valley Ranch. Starting at the Eagle Trailhead and walking west gives you views of the foothills and glimpses of the Indian Peaks with Boulder Reservoir and the plains behind.

In half a mile there's a junction with Sage Trail. If you turn right, you can make a 3.7-mile loop back to Eagle Trailhead or a 1.6-mile one-way hike to Boulder Valley Ranch Trailhead, shorter than the Eagle/Cobalt route.

We prefer to stay on Eagle Trail, which skirts the lower end of a shallow pond where ducks, geese and other water birds congregate if the ice is thawed. If the pond is frozen, listen to the ice grumbling to itself. That eerie sound is not a bird in the cattails as we first thought.

In one mile there is a second junction with Sage Trail that follows Farmers Ditch or 0.7 miles back to Boulder Valley Ranch. The more scenic route continues on Eagle Trail. Just beyond the intersection with Sage, the path becomes a bit steep and may be icy. At the top of the mesa your reward is a long, level stretch and good views.

In a short distance you join Mesa Reservoir Trail. The reservoir, which was iced over in late January, lies left of the trail. A closure in effect around the wetlands protects wildlife.

Continue walking on the mesa top to a junction with Cobalt Trail. Eagle Trail continues another 0.4 miles to end at Foothills Trailhead. Cobalt Trail drops down and passes below the ruins of an old smelter used in the 1930s and '40s to end at the Boulder Valley Ranch Trailhead.

In spring, evening primrose, false mallow and several species of cactus, mustard, vetch and penstemon bloom on the shale cliffs and along Cobalt Trail. In winter, a few rose hips persist and black seeds in the yucca pods rattle when you shake them.

Because there is little shade, we prefer hiking here in winter, and we sometimes do a car shuttle between the trailheads. The network of trails (mostly old farm roads) allows you to make various loops and permutations. In addition, Left Hand Trail connects Sage Trail to Neva Road, skirting Lefthand Valley Reservoir and the Beech Open Space picnic pavilion.

Farmers Irrigation Ditch, built in 1862, provided power for the Yount McKenzie Flour Mill near the mouth of Boulder Canyon and has provided water to area farmers for more than a century. Early in the 20th century, cattle ranchers W. W. Degge, W. W. Wolfe, Clinton Tyler, the Burger family and the Maxwell family sometimes ran cattle from here over Rollins Pass to Steamboat Springs to take advantage of nutritious mountain grasses.

The adobe brick building at the ranch, the oldest structure still in use, was built in the early 1900s.

Ruth Carol and Glenn Cushman are the authors of "Boulder Hiking Trails," published by Graphic Arts Books

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