After being closed for half a year, the trails at Walden Ponds Wildlife Habitat are again open, and spring migrants are arriving. On our first foray around the ponds since the closure, we watched great blue herons guarding nests just beyond the west end of the complex. An osprey flew overhead, a fish held lengthwise in its beak. Pelicans made a snow-white raft as they fished communally in Cottonwood Marsh. And, a great white egret stalked gracefully around a pond shoreline as a breeze ruffled its breeding plumage.

If you go early in the morning, you may see white-tailed deer, mink or muskrats or watch a snapping turtle laying eggs. Listen for the dawn chorus of birds as well as loudly chorusing frogs. Later in the day when temperatures rise, dragonflies, damselflies and butterflies abound, and painted turtles bask on logs. Orb weaving spiders often festoon the picnic gazebo, and after a rain, funnel spider webs on the boardwalk glitter with diamonds. Soon, attentive goose parents will be taking their fuzzy yellow chicks for a swim. This is one of our favorite places in all of Boulder for wildlife watching.

The 102-acre network of ponds, marshes and cottonwood groves is more conducive to wandering than linear hiking and lends itself to a variety of loops and figure eights. One of our favorite meanders is to start at Cottonwood Marsh, north of the parking lot, and take the one-way boardwalk through a stand of cattails where rails sometimes nest.

At the end of the boardwalk, turn right, head up to the gravel road and turn right again. Continue north to the sewage treatment plant intersection, and turn left. At the sign for the Ricky Weiser Wetlands, you can either turn left and walk between Bass Pond and Pelican Marsh to return to the gravel road leading back to the parking lot, or you can continue west and loop around the west end of the complex, stopping to watch herons nesting just west of a line of junipers. Continue following the trail to the fence dividing Walden from Sawhill Ponds. Head east to complete the loop.

Sawhill Ponds are slated to reopen May 23, weather permitting, and people can see the current status of the Sawhill Ponds closure on OSMPTrails.org. When the area does reopen, you can extend your meander into this adjacent wetland. Look for an osprey nesting platform on the southern edge of this section and for warblers and owls in the woods on the western edge.

Both Sawhill and Walden areas were mined for gravel from 1958 to the early 1970s, when wetlands were restored and the roads (now trails) were closed to vehicles. Walden Ponds are not named for Thoreau’s Walden, as many think, but for Walden Toevs, a former Boulder County commissioner who promoted open space preservation. Sawhill Ponds are named for the Sawhill family, early settlers and farmers in the Valmont area.

To reach Walden Ponds, drive north on 75th Street between Valmont and Jay roads and turn west at the sign. The entry to Sawhill Ponds (still closed) is just south of Walden.

Ruth Carol and Glenn Cushman are the authors of “Boulder Hiking Trails,” available from Amazon.