Wednesday, November 28, 2012
Yesterday we had a rather uncommon bird on the Refuge...a Greater Scaup. This diving duck spends its breeding season well north of us in Alaska in the west and northern Canada to the east. Then, come winter, the Greaters move south along the coastlines - rarely straying inland - but sometimes seen mixed in with other flocks of divers such as Redhead, Canvasback, Ring-necked duck and their cousins, Lesser Scaup. So - when our Biologist, Howard Browers, returned to the office after a bird survey reporting he had seen one female Greater Scaup, the buzz zipped around the birders like static on wool socks.
Luckily, as an avid and experienced birder, Howard asked me to try and go back out and confirm the sighting...and it just so happened I needed to get out and clean our Auto Loop restrooms as well, so the timing was perfect. After performing my watercloset duties, I drove to where the bird had been spotted and YES...she was still there - in bold browns, blacks and whites - to be confirmed and seen.
Greater Scaup are one of the very few circumpolar duck species, over 80% of the population wintering along the coasts in the Atlantic flyway, but small numbers do winter out here in the West. Preferring shallow water lakes and ponds in the summer - the Greaters switch to coastal, shallow, salt-water bays and brackish river inlets in the winter. In Utah, most sightings happen around the Great Salt Lake, so it was unique to find one in the fresh water wetlands of the Refuge. But then, in winter, scaup switch from their summer diet of insects, crustaceans and mollusks to a much more green diet of submerged plant matter, so the Refuge seems like a great place to stop for a snack.
Now, the scoop on differentiating between Greater and Lesser scaup is a bit tricky. But here are some key characteristics or field marks to look for: Head shape. Greater scaup are slightly larger than Lessers, with a noticeably larger and more rounded head. I like to think of it as a clear, curvy S shape from back up to bill on the Greater. Whereas, Lessers have a flatter back-of-the-head area that comes to almost a point at the back of the crown - much more like Ring-necked ducks. This shape - to my eye - always makes it look like the Lessers are looking down a bit, head tilting down toward the water. Another great clue, if you see a male, is the color of the head. Greaters tend to have a much more green irridescent wash on their head unlike a darker blue/black/purple on Lessers - but this is not always clear unless seen in the right light. And another way to differentiate between male scaup is the amount of white and quality of white/grey on the sides of the bird. Lessers are much more grey overall...contrasting shades of grey from sides to back, whereas the Greater males are very bright white to white-ish grey on the sides - a much bolder contrasting set of colors. Now of course, little of that helps in differentiating female scaup. Both have white cresents before their eyes and are mostly brown. Using the head size and shape helps, and female Greaters seems to be "brighter" or to have bolder, constrasting patters of browns/blacks and whites. And finally, bill size. Greaters have larger and slightly wider bill than Lessers. All of this is much easier seen when both species are present and comparisons can be made.
So, that's the scaup scoop for today. I hope you enjoyed and learned a little...but even more so, I hope you have the opportunity to observe these stately and handsome duck in the wild...if not here on the Refuge, perhaps along one of the coasts this winter.