Lesser Scaup

Greater and Lesser Scaup are notoriously difficult to tell apart. Important field marks include head shape and the extent of white in the wing (only visible when the wing is open), and caution and a good field guide are highly recommended. Both species occur in New Hampshire as non-breeding visitors, and during migration and winter habitat can be an important additional clue. Greater Scaup prefer larger bodies of water, and regularly use salt water, while Lessers are rare on salt water and more often seen in smaller, more vegetated ponds and wetlands. Each winter hundreds of Greater Scaup can be found on Great Bay, while Lesser is rare and localized between November and February. Sometimes the two occur in the same flock, providing an excellent opportunity to practice identification skills.

Scaup feed primarily on aquatic invertebrates, and some aquatic plant seeds, that are obtained by diving. They use their feet to propel them under water, and typically forage in water less than 20 feet deep. Both species nest in wetlands embedded in open habitats such as tundra or prairie, with Greaters across the north from Alaska to Labrador and Lessers in the west from Alaska to Oregon and Colorado.

Again because of the identification challenges, the two species are not distinguished on waterfowl population surveys. Available data indicate that populations of both are declining to some degree, with the largest declines in Greater Scaup. Where Lesser Scaup breeds in the Absence of Greater (e.g., the western United States) it appears to be increasing, although there are fewer birds here compared to the northern half of the range. How trends on the continental scale relate to birds in New Hampshire is difficult to determine, largely because both species are relatively rare here compared to other parts of their non-breeding ranges.