Walden Ponds/Sawhill Ponds Complex
- Boulder County
Aliases: Sawhill Ponds, Cottonwood Marsh
Description: This is one of Boulder's premier birding sites due to its wide variety of habitats. The Walden Ponds area is a Boulder County Open Space. The Sawhill Ponds area abuts it to the south, and the two are for all practical purposes the same, although they have different parking lots.
The largest and often the birdiest pond in the complex is Cottonwood Marsh, just north of the Walden Ponds parking lot. When water levels are low it can be excellent for shorebirds; when they are higher, for dabbling and diving ducks. Gulls, waders, cormorants, and other waterbirds are a good bet. During migration, swallows occasionally gather in enormous flocks over the water.
The marshy part of Cottonwood Marsh is traversed by a boardwalk just west of the Walden Ponds parking lot. Virginia Rail, Sora, and Wilson's Snipe breed here, and it can be a good spot for wintering sparrows possibly including a White-throated, Harris's or Swamp.
The numerous paths around the Walden/Sawhill complex provide access to a large number of ponds, each with its own water level and vegetative structure. Most of the regular waterbirds can be found here in season, though shorebird habitat outside Cottonwood Marsh is often limited. American Bittern is probably a regular summer resident, moving between the larger reedbeds, but it can be difficult to see or hear. Dawn and dusk may be your best bet, as with the Black-crowned Night-Herons that are more numerous and easier to see. The brush and trees around the ponds will produce all the typical birds of lowland woodland edge habitats, including some locally uncommon species like Eastern Kingbird and occasionally Orchard Oriole. Foothill birds like Rock Wren and Green-tailed Towhee can be common in migration.
The western edge of the main footpath loop gets close to the mature forests along the creek, skirting the best habitat for migrant and breeding landbirds. Great Horned Owl and Eastern Screech-Owl are resident in these woods. The creek, which runs to the west of the path, is your best bet for Wood Duck.
Habitat: Pond/Lake/Reservoir, Lowland Riparian, Marsh, Hedgerow/Shelterbelt, Stream
Directions: The Sawhill Ponds parking lot is at the end of a short, signed access road which heads west from 75th Street just north of the railroad crossing, about a half mile north of Valmont Drive east of Boulder. The Walden Ponds parking lot is at the end of its own short, signed access road which heads west from 75th Street a short distance north of the Sawhill Ponds access road.