Lesser & Greater Scaups: Late March Spring Migration through Northrn Illinois

A sunset at Rock Cut State Park in Rockford; A great place to go birding in Northern Illinois; 4/9/11.

A mix of Greater Scaups and Lesser Scaups on Pierce Lake; Rock Cut State Park, Rockford, IL; 3/26/11.

By late March another wave of birds were making appearances throughout Northern Illinois. The vast majority of this group were waterbirds arriving on area ponds, lakes, and marshes. Within the last week of March, I have seen lots of new arrivals: Hooded Mergansers, Wood Ducks, Blue-winged Teals, Scaups* (both Greater & Lesser), Ruddy Ducks*, Canvasbacks*, Buffleheads*, Pied-billed Grebes, Horned Grebes*, Double-crested Cormorants*, Black-crowned Night Herons, and Red-breasted Mergansers*. Non-water birds also showing up were Ospreys*, Eastern Phoebes, Chipping Sparrows, and Turkey Vultures.

* These birds are migrating through, not making Northern IL their summer home.

In my series about birds migrating through Illinois (not spending the summer in N. IL) on their way to their summer haunts, this weekend and next weekend, I'll features photos of some of these birds*: Scaups, Canvasbacks, Ruddy Ducks, Horned Grebes, Buffleheads, Red-breasted Mergansers, and Ospreys.

A Lesser Scaup can be distiguished from its Greater cousin by its smaller size,
its smudgy flanks, and taller head, Suguaro Lake, AZ; 12/29/09.

Another look at the Lesser Scaup, Suguaro Lake, AZ; 12/29/09.

I am not exactly sure about making positive identifications between Greater and Lesser Scaup, as they look almost identicle, especially from a distance. Lesser Scaups are smaller at 16 1/2" long; whereas the Greater Scaups are larger at 18" long. Unless they were next to eachother for comparison, I would not be able to tell them apart. However, two other traits that one can look for is that the Lesser Scaup's flanks (Above) are smudgier and the barring is more coarse. The Greater Scaup's flanks are clean white with no marks.The Lesser's head is taller and narrower than the Greater's, which appear to be lower and a flatter arc. Otherwise both birds have blackish heads and breasts, bright yellow eyes, blue bills, and white flanks and belly. In flight the Lesser Scaup has less white on its wings (Below). Both female species (Below) also look similar with brownish/grayish bodies, darker brown breast, head and wings, blue-gray bill and white along the base of the bill.

A pair of Lesser Scaups (male on left, female on right),
Rock Cut State Park, Rockford, IL; 3/31/11.

Lesser Scaups in flight, Rock Cut State Park, Rockford, IL; 3/27/11.

Greater Scaups and a female Canvas Back, Nygren Wetlands, Rockton, IL; 4/10/11.

In the photo (Above), two traits make me think these are Greater Scaups and not Lesser's. The flanks of the Scaups are cleaner with no smudges on the white flanks, and the tops of their heads seem to be slightly flatter than the Lesser's head (2nd & 3rd pics from top). Plus the size of these Scaups is closer to the size of the Canvasback (which can grow to 21" long) that is swimming with them, so the Greater's length of 18" is more likely than the Lesser's 16.5" length.

Lesser Scaups are far more commonly seen than the Greater Scaups. During winter months, Lessers can be seen throughout most of the southern half of the U.S. as well as along both coasts. In summer they will be found throughout  most of  Alaska, Western and Central Canada, most of Ontario, and parts of extreme northern Quebec and Newfoundland. Greater Scaups can only be found along the Pacific and Atlantic Coasts in winter ( and a strange pocket along the southern Mississippi River in Arkansas). In summers they migrate to the very northern sectons of Canada (Yukon, Northwest Terrirorries, Nunavit) and Alaska. Greater Scaups are more likely to be found on saltwater than Lesser Scaups.