Having just returned to Colorado, I saw the first western grebes of the season this morning; a pair of those slender divers was feeding on a lake in South Platte Park, in Littleton. Western grebes are generally found in the State from April through October and pair off soon after they arrive. They favor lakes and reservoirs with extensive open water for fishing and marsh-lined shores for nesting; common along the South Platte and Arkansas Valleys of eastern Colorado, western grebes also inhabit lakes of the mountain parklands and western Colorado valleys.
The renowned mating dance of these graceful birds is best observed in late April and early May. Nests are generally placed on mats of floating vegetation, anchored to reeds and hidden amidst the marsh plants. Three or four eggs are laid and, as with other grebes, the young ride on their parents backs after hatching; while the buoyant youngsters pick insects from the surface, the adults dive for fish and a variety of aquatic invertebrates.
Beyond Colorado, western grebes breed on freshwater lakes from the western Great Lakes region to the Pacific Coast and from southern Canada to Kansas, Colorado, the Colorado Plateau, the Great Basin and California; the very similar Clark's grebe inhabits the southwestern section of this range (including Colorado). By November, most have departed for bays and estuaries along the Pacific Coast, from southern Alaska to Mexico.