Throughout the historical period, the Least Sandpiper was a steady and constant sight on migration, known to breed well to the north and to winter well to the south. For this reason, possibly no Confirmed breeding species in Massachusetts history is more exceptional than the Least Sandpiper found on Monomoy Island in 1979, the last year of Atlas 1 surveys. The single dead chick found there represented the first (and, to date, the only) known instance of the Least Sandpiper to ever breed in the lower 48 United States. Although the normal breeding range of the species is far to the north in Newfoundland and across Canada, considerable numbers of migrant Least Sandpipers pass our shores every spring and fall. The Monomoy nesting, which is as unlikely as a Snowy Owl nesting on Cape Cod, remains a bizarre and intriguing mystery. No breeding Least Sandpipers were found in Massachusetts during Atlas 2. The single Possible observation was recorded on the first day of the Safe Date period and was not recorded again, suggesting that it was probably only a late migrant.