Lesser scaup that looks strongly curved or even angular due to the small crest. When the birds raise their heads, these differences are most easy to spot, and after observing the two species in direct comparison it usually becomes easy to recognize. In fact, in alternate plumage the lesser scaup drake may appear identical in shape and size to a drake of the ring-necked duck ("A. collaris"); the black back and wings of that species are hard to confuse with the light ones of the lesser scaup male though. Particularly in the case of vagrant birds in Europe, the identification is complicated
Lesser scaup not threatening in respect to the enormous overall numbers, the lesser scaup is classified as a Species of Least Concern by the IUCN. An increase of the decline is liable to result in an uplisting to Near Threatened or even Vulnerable status. The causes for this stark—though not threatening yet—decline remain unknown. There are indications that the breeding success is decreasing, but why this is so remains puzzling. On one hand, pollution and habitat destruction, especially in the wintering regions, has certainly increased since the early-mid 20th century. On the other hand, the narrow time frame in which lesser scaup