On 26 October 1975 we discovered an immature Sharp-tailed Sandpiper (Calidris acuminata) at Hiram Prince Lake II, a small pond 1 mile north of Lafayette, Boulder County, Colorado. It was observed foraging in a loose association with four Pectoral Sandpipers (C. melanotos). Nearby were eight Killdeer (Charadrius vociferus) and four Long-billed Dowitchers (Limnodromus scolopaceus). On 31 October we trapped and banded the Sharp-tailed and took a series of photographs, measurements and feather samples. Slide duplicates are on file at the Denver Museum of Natural History. Later that day we released it at the same pond, where it remained until 6 November 1975. During this 12-day period many other observers saw the bird. This is the only recorded occurrence of this species in Colorado.
The plumage description detailed below is taken from notes made on 31 October while the bird was in hand. Table 1 summarizes useful field characteristics of Sharp-tailed and Pectoral sandpipers.