Birding Around Denver After A Snowstorm

November 11, 2019

Richard Stevens:

High temperature today reached a nippy 24 degrees.  Winds ranged from 9 to 12 mph with several gusts at 22 mph.

I left for Chatfield State Park (Jefferson/Douglas) around 4:30 am to beat traffic.  Target birds during a drive up and down Deer Creek Canyon Road were Northern Pygmy-Owl or Short-eared Owl; neither found this trip.

I scoped Chatfield Reservoir from above the dam.  Target birds were any Murrelets; none was found.

The two White-winged Scoters were swimming off the south marina.  Nothing else uncommon was found.

The Black Scoter was found when I scoped Bear Creek Lake (Jefferson).  Again, no other uncommon birds were found.

A brief stop at South Platte Park (Arapahoe) did not find the Nashville Warbler reported yesterday.  Perhaps last night's snowstorm encouraged it to move on to warmer places.

I took the toll road to Aurora Reservoir (Arapahoe).  Again, most gulls were at the shores of mile 2.0 or 4.5.  I could pick out an adult Lesser Black-backed Gull at mile 2.0 (from lower parking area pavilion).  Gulls were too far away to identify a Mew Gull (previously reported).

My final stop of the day was Cherry Creek Reservoir (Arapahoe).  I found a strange looking sparrow with a flock of American Tree Sparrows (14) along the Lake Loop at Cherry Creek Reservoir.

The face appeared similar to an adult Chipping Sparrow (gray face, blackish eye line, white supercilium) but had characteristics of an American Tree Sparrow (bicolor bill, rufous patch on sides, isolated dark spot on chest).

I spent an hour trying to photograph the bird.  My seven or eight photos were blurry because of fading light.  It seemed that every time the flock came down to the Lake Loop road, a car would come by.

I checked the "Handbook of Avian Hybrids of the World" and found no mention of a Chipping Sparrow/American Tree Sparrow hybrid.  Their breeding grounds are quite far apart.  It was interesting how many times Chipping Sparrows, Clay-colored Sparrows, Brewer's Sparrows and Field Sparrow interbred.

Will do additional research later.  The Yellow-billed Loon, one Common Loon and two Bonaparte's Gulls continue.  Dozens of American White Pelicans, a few Double-crested Cormorants, many Horned & Eared Grebes (no Red-necked Grebe) and Western Grebes are also still there. 

Since it was getting late anyway, I stayed around until after sunset to look for owls.  I found one Long-eared Owl, no Barn Owls.