Recent cold weather has resulted in many local bodies of water becoming frozen.  Some reservoirs still have a bit of open water due to slight currents of incoming water or some have aeration systems to help address low oxygen levels and potential algal blooms and their pumping helps keep the water open.  Some of the reservoirs at South Platte Park are largely frozen over currently with some daily shifts where a small area may open as the day progresses but then freeze again at night.  We found considerable open water at South Platte Reservoir, which has an aeration system; there was a bit of open water at the south end of Eaglewatch Lake, where there’s a slight inflow; Blackrock Lake was completely frozen (at least in the morning); and, the South Platte River had plenty of open water.

On Saturday morning we quickly determined that spending time along the South Platte suited our purposes best.  Many good close-range views were to be had of ducks on the river, and we recorded thirteen species for the day – five dabblers and six divers on the river and then two more divers on the reservoir.  As this was a Beginners’ Bird Walk we went over a lot of details on how to identify the species, the drake and hen of each species, and to even tell some of the first-year males from adult males.  

One of our first ducks was a male Green-winged Teal which had the usual dark cinnamon head with the green postorbital swoop.  However, the white vertical bar at the front of the sides was not quite as crisp as it would be on a full adult, the flanks were mottled brown instead of uniform gray, and the generally distinctive pale-yellow rump (above the black undertail coverts) was not to be seen.  

We also saw a “ton” of Hooded Mergansers.  Once we had sorted out that the male has a white hood bordered in black, warm cinnamon flanks, and two black “spurs” on the side of its breast; and that the female, though rather drab, has an incredible punked-out crest of her own; we noted that while the female has dull, beige-orange eyes the male has bright yellow eyes, and this includes first year males.  A good distinguishing trait to look for is that all females, regardless of age, have a dark upper mandible with orange edging and a dull orange lower mandible; young males can have a bit of orange edging on the upper mandible, but for the most part they will have an increasingly dark bill as they become adults.  Additionally, the longitudinal white striping that we see on the back of a Hooded Merganser while not in flight is actually part of the wing closest to the body (the tertials), and the white bands are more obvious in the male.

Finally, I have one additional cautionary note regarding these first-year males.  First-year male Buffleheads can be almost indistinguishable from adult females.  They too have a white oval cheek patch which can be a bit larger than the females’ or have a bit of a tailing swoop, but this is bordering on graduate-level birding.

We visited South Platte Reservoir at the end of our walk, which has much deeper water than the river, and here we picked up a couple of more diving ducks.  There were a good number of Ruddy Ducks which are small, often have their long tails cocked up, and the males have distinctive white cheeks.  We also had distant views of a pair of Red-breasted Mergansers – perhaps my favorite Colorado duck.  May you all be blessed with seeing some this winter.  

Good birding!  Chuck


South Platte Park, Feb 5, 2022 
32 taxa

30 Canada Goose
6 Northern Shoveler
15 Gadwall
13 American Wigeon
44 Mallard
20 Green-winged Teal
4 Ring-necked Duck
14 Lesser Scaup
38 Bufflehead
19 Common Goldeneye
30 Hooded Merganser
22 Common Merganser
2 Red-breasted Merganser
27 Ruddy Duck
3 Pied-billed Grebe
12 Rock Pigeon
5 American Coot
1 Killdeer
17 Ring-billed Gull
2 Herring Gull
1 Cooper’s Hawk
2 Bald Eagle
5 Red-tailed Hawk
2 Belted Kingfisher
2 Northern Flicker
1 American Kestrel
5 Black-billed Magpie
16 American Crow
2 Black-capped Chickadee
3 European Starling
2 House Finch
1 Song Sparrow