Should you ask Americans to list wildlife species native to Colorado, most would mention bighorn sheep, elk and mountain lions. Few would include pelicans, ibis, egrets and shorebirds on their list but these birds, usually associated with southern coasts, are common summer residents and migrants on Colorado's Eastern Plains.
Late summer is the best time to observe these aquatic birds as they gather at many of the large reservoirs along the South Platte Valley. By August, large mudflats are forming along the shrinking lakes, providing ideal feeding grounds for migrant shorebirds. Large flocks of gulls also begin to congregate on and along the reservoirs; these include California, ring-billed and Franklin's gulls. American white pelicans, double-crested cormorants and western grebes gather to rest and feed on the lakes prior to migration and smaller numbers of common, Forster's and Caspian terns may also be observed. Wetlands and shallows along the margin of the lakes attract snowy and cattle egrets, long-billed curlews, marbled godwits, American avocets and white-faced ibis.
Some of the better locations to visit include Barr Lake State Park, northeast of Denver, Jackson Lake State Wildlife Area, northwest of Ft. Morgan and the Prewitt Reservoir State Wildlife Area, southwest of Sterling. My favorite spot is Latham Reservoir, southeast of Greeley; the area along County Road 48, on the south side of the Reservoir, is especially interesting.