I think it's safe to say that any relatively experienced birder who observes four life-listers while walking through a city park in the middle of winter would be absolutely thrilled, to say the least. Yesterday we enjoyed unseasonable temperatures and took our dog Sushi for a walk in Denver's City Park. Stopping to take in the scenery at Duck Lake, we were excited to find a diversity of waterfowl gathered on its waters. We kept Sushi on his leash and observed the diving and dabbling ducks from a distance, letting my camera do all the work.
Male Common Goldeneye (Bucephala clangula) in breeding plumage
The first duck that we observed was a Common Goldeneye (Bucephala clangula), who startled us with its shimmering yellow eye and dazzlingly colorful plumage. Despite occasionally disappearing to dive for invertebrates and fish, this duck didn't seem to mind our presence. Common Goldeneyes breed in the boreal forest of northern Canada and Alaska, where they find tree cavities up to 40 feet high in which they make their nests. Sometimes females will lay their eggs in the nests of other females and/or in the nest of other species of ducks like Barrow's Goldeneye. Hooded Mergansers and Wood Ducks are known for this odd behavior as well (Cornell University 2019).
Male Northern Shoveler (Spatula clypeata)
Female Northern Shoveler (Spatula clypeata)
The Northern Shoveler (Spatula clypeata) was by far the most common duck we saw. Aptly named, these dabbling ducks use fine comb-like projections called lamellae on their spatula-like bill to filter out crustaceans and aquatic invertebrates from the water. We saw them swimming in circles, with one often following another who had stirred up particulate matter. Northern Shovelers are cosmopolitan, found all around the world into Europe, Africa, and Asia (Cornell University 2019).
Male Hooded Merganser (Lophodytes cucullatus) in the foreground and a male Redhead (Aythya americana) behind him
Two of the most thrilling sightings for me were a male Hooded Merganser (Lophodytes cucullatus) and a male Redhead (Aythya americana). The Hooded Merganser is a sight to be seen, with stark chestnut, white, and black colors that seem to jump out at you, especially in the sunshine. Hooded Mergansers are gifted underwater hunters. They have great underwater eyesight and a transparent nictitating membrane that protects their eyes when hunting for fish and macroinvertebrates. Hooded Mergansers are our second smallest species of Merganser (after the Smew of Eurasia) and the only Merganser that is entirely restricted to North America (Cornell University 2019). The Redhead was also quite a jaw-dropper. This species is quite social, and we saw around 12 gathered together in a mixed-species flock at the far side of the pond. Rafts of up to 60,000 Redheads can be seen in the Gulf of Mexico during the winter. I mentioned the Common Goldeneye's brood parasitic behavior above; the Redhead is even more active in laying its eggs in other species' nests. Redhead eggs have been found in the nests of Mallards, Canvasbacks, Northern Pintail, Gadwall, Northern Shoveler, Ruddy Duck, and American Wigeon (Cornell University 2019).
Male Bufflehead (Bucephala albeola) with iridescent plumage
This afternoon's sunlight gave us a real appreciation for the iridescent violent and purple hues on the head of the male Bufflehead (Bucephala albeola). Another diving duck, the Bufflehead nests almost exclusively in holes excavated by Northern Flickers, and sometimes by Pileated Woodpeckers. Unlike many other ducks, they form monogamous relationships with mates (Cornell University 2019).
Male Ring-necked Ducks (Aythya collaris). Notice the peaked head and white ring around the bill
The last duck we saw that was new to us was the Ring-necked Duck (Aythya collaris). This species can be quickly identified by its peaked head and white ring around the bill. The chestnut collar around the black neck of the male is extremely difficult to see but was noted on dead specimens by the 19th century naturalists who identified the species. These diving ducks will use very shallow bodies of water and are known to congregate in giant flocks of several hundred thousand birds during migration on lakes in Minnesota.
Male Mallard (Anas platyrhynchos) glowing in the Colorado sunshine
And of course, we were graced by the presence of the ubiquitous Mallard (Anas platyrhynchos). I never grow tired of seeing the flashy plumage of a male Mallard duck, especially when the sun is shining. Mallards form monogamous pairs, but males are guilty of unsolicited extra-pair copulations, something not dissimilar to rape in the human world. Females encumber all parenting duties, incubating the eggs and raising the offspring on their own. It is also only the female that produces the quacking sound we associate with ducks. Males don't quack; they only make a softer rasping sound.
A Red-tailed Hawk (Buteo jamaicensis) alights on an Plains Cottonwood (Populus deltoides monilifera) dotted with Double-crested Cormorant (Phalacrocorax auritus) nests
High up in the canopy of a Plains Cottonwood (Populus deltoides monilifera) sat a Red-tailed Hawk (Buteo jamaicensis), looking down on the smorgasbord of waterfowl. Unfortunately, we did not see the raptor make any hunting attempts, but it looked plump and content, so maybe we missed it?
All in all, it was great day of unexpected novelties. As much of a bird nerd as I am, I still have many species to observe in the field, particularly among the waterfowl. I look forward to more birding adventures where learning and discovery are unending.
References
Cornell University. Guide. Accessed June 29, 2020. [https://www.allaboutbirds.org/guide]