Walden/Sawhill Ponds Complex, March 14th – with Stephen Chang

The Saturday of March 14th, I led a group of 7 on a chilly morning to Walden Ponds wildlife habitat for our monthly birdwalk. We won’t be having another walk until, at the earliest, May 9th (maybe later), but we made the most of our last walk by observing 31 different species! Highlights included at least four different Bald Eagles (two adults and two juveniles), the area’s winter resident Harlan’s Hawk, and a very cooperative Northern Shrike.

Northern Shrike (c) Sibylle Hechtel

 

Northern Shrikes are a winter visitor here to the front range, but they breed up in the arctic tundra/taiga. Shrikes are our only predatory songbird, and during the winter the Northern Shrike will eat mostly other small songbirds and small rodents. In arid, open habitats across the front range, the Northern Shrike is replaced by the Loggerhead Shrike in the summer. They will eat small birds, mammals, reptiles, and insects.

Loggerhead Shrike (c) Jamie Simo

 

Our full eBird checklist can be found here: https://ebird.org/checklist/S65787632 

 

There is still plenty of migration to be had, so be sure to get out and look at some birds. Spending time in our natural areas is a easy way to practice social distancing. Happy Spring and be well!

Best,

Stephen Chang

Wheat Ridge Greenbelt, March 7 – with Chuck Aid

Northern Shoveler (c) Bill Schmoker

Weather-wise we had a beautiful day at the Wheat Ridge Greenbelt.  Interestingly enough, it did not translate into a slew of birds.  We had a reasonable number of species – thirty, but the overall number of individual birds was not great.  And, I had a comparable birding day on Friday. It seems that with this good weather some birds may be feeling inclined to do a migratory step north and have left the area, e.g. Northern Shovelers who have been around in the hundreds, and perhaps other birds are not feeling too stressed about food so they’re less active. I’m curious to see if the next round of inclement weather will cause an increased surge in bird activity.  There’s always something to be learning more about with this avian world.  I just try not to get paranoid about a temporary decrease in numbers really reflecting the overall decline in birds that we know is going on.

Gadwall (c) Bill Schmoker

So, as for the birds we did see, they are all looking spectacular in their breeding plumage.  We had wonderful close looks at Gadwall, Green-winged Teal, and Hooded Merganser.  Glorious! And there were several hints as to the onset of breeding season – Gadwall and Mallards doing a bit of courtship behavior, Double-crested Cormorants starting to build and occupy their nests on the Tabor Lake island, and House Finches singing their wonderful song.

We also had a couple of interesting raptor observations.  Red-tailed Hawks are found in Colorado throughout the year and in recent weeks they’ve been busy finding mates, building nests, and in some cases even starting to incubate eggs.  We might start to see nests with young by the middle of April – the incubation period is roughly 30-33 days.  On our walk we had one pass right over us a couple of times so that we got excellent looks, and I want to reiterate some of the field marks we discussed. 

Red-tailed Hawk (c) Bill Schmoker

First of all, Red-tails belong to the group of hawks known as Buteos – these are the large soaring hawks and include Ferruginous and Swainson’s Hawks.  Buteos are medium to large robust hawks that hunt primarily while soaring.  Their wings are long and broad, and their tail is relatively short.  Red-tails have a huge variety of plumages but there are a few characteristics that are almost always present.  The wings tend to be more truncated and rounded than the other Buteos, and they have distinctive “bulging” secondaries causing the wings closer to the body to look even broader than those of the other Buteos.  Also, to varying degrees all Red-tails have a dark leading-edge of the wing (the patagium).  An interesting behavioral characteristic is that, when coming in to perch, Red-tails tend to fly in low and swoop up to the perch at the last moment.

Prairie Falcon (c) Rob Raker

Our other raptor of note was a Prairie Falcon which showed several characteristics leading to our being able to identify it.  It flew by going low and fast, the pointed wings flapped rapidly, stiffly, shallowly, and without pause.  It appeared only slightly smaller than a Red-tail but was more svelte (they weigh about two-thirds as much).  Finally, the real clincher was that it had black axillaries (armpits), which is diagnostic.

We are now only about a month out from the onslaught of Spring migration, and someone locally, as hard as it is to believe, has already reported a Broad-tailed Hummingbird. Also, Mountain Bluebirds are back in the area.

So, get your hummingbird feeders all set, and make sure you’ve got some binoculars that work.  Good optics make a world of difference!

Chuck

Wheat Ridge Greenbelt, Mar 7, 2020
30 species

Canada Goose  55
Northern Shoveler  18
Gadwall  50
American Wigeon  3
Mallard  35
Green-winged Teal  28
Redhead  1
Ring-necked Duck  2
Bufflehead  1
Common Goldeneye  3
Hooded Merganser  3
Rock Pigeon (Feral Pigeon)  8
Virginia Rail  2
American Coot  18
Killdeer  1
Ring-billed Gull  50
Double-crested Cormorant  30
Red-tailed Hawk  2
Belted Kingfisher  1
Downy Woodpecker  1
Northern Flicker  4
Prairie Falcon  1
Blue Jay  1
Black-billed Magpie  1
American Crow  2
Black-capped Chickadee  12
American Robin  3
House Finch  9
Song Sparrow  3
Red-winged Blackbird  11

Hudson Gardens, Feb 29 – with Chuck Aid

Green-winged Teal (c) Bill Schmoker

The weather forecast for Saturday said it should get up to about 62 degrees.  It may have eventually gotten that warm, but it was far from it at 8 AM. Fortunately, we had a fair amount of bird activity to help keep us warm.  We began by checking out the pond immediately behind the Welcome Center, and were rewarded by a pair of Gadwall, a few Mallards and Canada Geese, and four male Green-winged Teal.  Then, in the next pond over we could see a couple of male Northern Shovelers.  This brings me to an interesting aspect of our morning.  We ended up seeing nine species of ducks, six of these were heavily dominated by males. We saw no female Shovelers or Green-winged Teal, 90% of our Mallards were males, and all of our Lesser Scaup, Common Goldeneyes, and Hooded Mergansers were males.  The only species with a semblance of balance were the Gadwall, American Wigeon, and Bufflehead.  Not sure where the girls were but given the rough treatment one female Mallard was receiving, we can imagine that for good reason many of them were not ready to hang out with the boys.

Lesser Scaup (c) Bill Schmoker

There was also a single American Coot on the river which has a superficial resemblance to the ducks, but rather than having webbed feet, it has long lobed toes and a stout, conical bill. 

We had one mystery raptor flying low and fast behind some trees.  At the time I identified it as a Prairie Falcon, but upon further thought I think it was probably a Cooper’s Hawk.  Both of these birds have long tails and fly powerfully with shallow, stiff, wingbeats; however, the Prairie Falcon flaps more consistently, and the Cooper’s Hawk has a flap-flap-flap-glide pattern.  While I did not get a great look at our bird and even thought that it might have had the pointed wings of a falcon, I did see this classic Cooper’s Hawk flight pattern, and base my final identification largely on that.

Hairy Woodpecker (c) Bill Schmoker

We also had a nice mix of finches and sparrows, many of whom were singing.  This included many House Finches, a single American Goldfinch, a nice mix of Dark-eyed Juncos, a single White-crowned Sparrow, a single Song Sparrow, and a single Spotted Towhee.

Perhaps the highlight of the morning was the woodpeckers.  We ended up with six Downy Woodpeckers, getting great looks at almost all of them, and then we had a pair of Hairy Woodpeckers.  These last are primarily resident in the foothills and mountains and only rarely make it out onto the eastern plains or into urban areas.  So, it is rare to see one in the city, and even more rare to see a male and female together, and even exhibiting some obvious pair-bonding.

Good birding!
Chuck Aid

Hudson Gardens, Arapahoe, Colorado, US
Feb 29, 2020
33 species (+2 other taxa)

Canada Goose  90
Northern Shoveler  2
Gadwall  12
American Wigeon  2
Mallard  23
Green-winged Teal  4
Lesser Scaup  2
Bufflehead  6
Common Goldeneye  1
Hooded Merganser  1
Rock Pigeon (Feral Pigeon)  2
Eurasian Collared-Dove  4
American Coot  1
Ring-billed Gull  7
Cooper’s Hawk  1
Red-tailed Hawk  2
Downy Woodpecker  6
Hairy Woodpecker  2
Northern Flicker  5
Blue Jay  2
Black-billed Magpie  1
American Crow  1
Black-capped Chickadee  14
Bushtit  4
European Starling  2
American Robin  11
House Finch  14
American Goldfinch  1
Dark-eyed Junco  5
Dark-eyed Junco (Pink-sided)  2
Dark-eyed Junco (Gray-headed)  2
White-crowned Sparrow  1
Song Sparrow  1
Spotted Towhee  1
Red-winged Blackbird  7

South Platte Park, Feb 1 – with Chuck Aid

Belted Kingfisher – female (c) Nona Radin

Another fun-filled bird walk with mild winter weather! Yahoo!  We started at the pond immediately north of the Front Range Birding Company along Remmington Ave.  Here, we got good close looks at a slew of Cackling Geese, a variety of ducks, and two individuals that I want to spend a bit more time on.  First, we had a Belted Kingfisher, that I misidentified as a first-year bird.  There were two things wrong with that assessment.  First of all, there are no juvenile kingfishers in mid-winter as they have acquired their adult plumage by October – I just didn’t think it through properly. Second of all, I was wrong about what I thought I saw with regard to our bird’s plumage. 

 

 

Common Goldeneye x Hooded Merganser – hybrid (c) Nona Radin

So, let’s get straight about Belted Kingfishers.  The male has a single gray upper breast-band, the female has the same gray band as the male PLUS a second rusty-colored breast-band lower down and a bit of the same rusty coloring in the flanks, and the juvenile is just like the female except the rusty breast-band is broken in the middle and does not extend all the way across.  In looking at the photo you can see that our bird was an adult female.  The second bird I want to bring to your attention was a hybrid Common Goldeneye x Hooded Merganser.  Though rare, these guys do occur with some regularity.

Hooded Merganser pair (c) Nona Radin

We then spent the majority of the morning visiting various ponds in the vicinity of South Platte Park.  Among the highlights were several pods of Northern Shovelers swirling around and creating a vortex to bring food up to the surface of the water.  We also saw an interesting convocation of over forty Buffleheads in one group.  And, we had great looks at a male American Kestrel, our smallest falcon.

American Pipit – winter (c) Jeff Jaacks

Our group began to dissipate around eleven o’clock, and several folks missed out on one of the more interesting birds of the morning – an American Pipit.  These small, slender, migratory birds are rather inconspicuous looking, occurring throughout North America and as far south as El Salvador.  They belong to an elite group of ground-inhabiting songbirds that breed in both alpine and arctic tundra, and here in Colorado they can be a fairly common summer resident above timberline.  In the winter, though, they are rather uncommon, being found occasionally along sandy shorelines of ice-free rivers, which is exactly where our bird was on Saturday. 

American Pipit – summer Colorado (c) Bill Schmoker

Back to the appearance of the American Pipit. David Sibley, well-known ornithologist and author/illustrator of many bird fields guides, has described the American Pipit as possibly “the most variably-colored songbird on the continent.”  This does not mean a lot of bright colors, just that within their inconspicuous subtle coloring there is a lot of variation.  Some of this can be ascribed to differences between the four main subspecies of American Pipit, which can generally be distinguished from one another based on the amount of yellow vs pink on the breast and belly, the darkness vs lightness of the legs, the extensiveness and boldness of the breast streaking, and the whiteness of the supercilium (eyebrow) and maIar (whisker).  In looking at the two photos here, our Saturday bird had faint yellow on the belly, bold streaking on the breast, and strikingly white supercilium and malar, making it I believe a member of the eastern subspecies (Anthus rubescens rubescens), while the other picture shows a Colorado breeder with hardly any of the characteristics mentioned above, making it a member of the Rocky Mountain subspecies (Anthus rubescens alticola).  However, I’m getting way over my head here, and haven’t even mentioned seasonal molt differences.  Finally, Sibley contends that much of this variation could simply be due to differences between individual birds. 

What a nice engaging pastime it is trying to always learn just a little bit more about our avian friends. 

See you on another walk soon!
Chuck

South Platte Park, Feb 1, 2020
29 species

Cackling Goose  500
Canada Goose  30
Northern Shoveler  200
Gadwall  12
American Wigeon  8
Mallard  39
Green-winged Teal  26
Ring-necked Duck  17
Lesser Scaup  16
Bufflehead  60
Common Goldeneye  34
Hooded Merganser  17
Common Goldeneye x Hooded Merganser (hybrid) 1
Common Merganser  4
Pied-billed Grebe  1
Rock Pigeon 16
Killdeer  5
Ring-billed Gull  5
Great Blue Heron  1
Bald Eagle  1
Red-tailed Hawk  4
Belted Kingfisher  3
Northern Flicker  2
American Kestrel  1
Black-billed Magpie  1
American Crow  8
Black-capped Chickadee  2
American Pipit  1
House Finch  4
Red-winged Blackbird  2

Hudson Gardens, January 25 – with Chuck Aid

Great Blue Heron (c) Nona Radin

A chilly morning gradually changed over to a delightfully mild late morning, and we had a great walk going upstream from Hudson Gardens, even included a brief detour up Lee Gulch where an American Dipper had been recently reported.  We whiffed on the Dipper, but did get great views of a number of other birds.

Cackling Geese (c) Nona Radin

For starters, we had a nice mix of Cackling Geese and Canada Geese out on the South Platte.  Generally speaking, there are four main characteristics that can be used in differentiating these very similar “white-cheeked” geese.  However, complications arise because there are roughly six subspecies of Cackling Goose and eleven subspecies of Canada Goose, all of which vary slightly in size, coloration, and shape.  The first, and perhaps most import characteristic, is the bill size, its shape, and its length, as compared to the width of the side of the head.  Compared to Canada Geese the bills of Cackling Geese are shorter, closer to being an equilateral triangular shape, and their length is about 50% (or less) of the width of the side of the head.  Overall, Cacklers are smaller (3.1 – 6.6 lbs), while Canada Geese are bigger (5.7 14.3 lbs).  Cacklers tend to have shorter, thicker necks.  And, finally, there are some subtle differences in plumages, e.g. some Cackler subspecies have darker breasts, some have a white neck-ring, and some have a grayish sheen on their back.  On Saturday we got good looks at both species, and started to work towards getting a little more tuned in to all these differences.

Pied-billed Grebe (c) Bill Schmoker

Another waterbird of interest that we saw was a Pied-billed Grebe.  “Pied” means having two or more different colors, and the name derives from their bill, during breeding season, being white with a distinct black band. Grebes are not ducks, as they have lobed toes, not webbed feet, to assist them in diving.  However, for the most part they don’t have to dive to go under water; they can simply adjust their buoyancy such that they can float with differing amounts of their body above the water, or they can simply slowly submerge themselves with hardly a ripple.

Buffleheads (c) Nona Radin

We also had six species of ducks on the river, and we got to really delve into their identification – working on telling the males from the females, and what the main plumage characteristics were.  One of these challenges had to do with telling first-year male Buffleheads from adult females (get out your field guides).  In looking at the photo notice how much bigger the adult male is.  Males tend to be about 1-3″ longer than the females, and weigh about 4 ounces more, so I’m saying that what we saw were females, but I am not confident in doing so.  

Greater Scaup (c) Nona Radin

The highlight of the ducks was getting to see a small flock of twelve Greater Scaup fly in and land right in front of us on the river. This is a rare to uncommon species on the eastern plains near the foothills, and we were quite fortunate to get excellent looks.  On the males we were able to note their bright white flanks, thick neck, head sloping towards the rear and long from bill to nape and smoothly rounded (no hint of the peaky head that characterizes the Lesser Scaup – a far more common winter duck), broad black nail on the tip of bill, eye not centered in head – but higher and more forward, BIG jowls, and some green noted in the head coloring. On the females we noted the extensive white behind bills.  Also, fortunately, one of our participants, Nona Radin, took some great photos.

Greater Scaup (c) Nona Radin

Finally, some of us got good looks at a single Ruby-crowned Kinglet traveling with a little flock of Black-capped Chickadees.  This diminutive bird with its tiny bill is a common summer resident up in the mountains, but it is a rare to uncommon winter resident on the eastern plains near the foothills.

So, though we only recorded 23 species, we got great looks at some really special birds – not to mention three muskrats.  Hope you can join us on a future Hudson Gardens bird walk, or check out the walks being offered on the first Saturday of each month by the Front Range Birding Company – call 303-979-2473 for more info and to sign up for a walk.

Good birding,
Chuck

Hudson Gardens, Jan 25, 2020
23 species

Cackling Goose  80
Canada Goose  300
Gadwall  11
Mallard  35
Green-winged Teal  9
Greater Scaup  12
Bufflehead  13
Common Goldeneye  6
Pied-billed Grebe  1
Killdeer  1
Ring-billed Gull  1
Great Blue Heron  1
Belted Kingfisher  1
Northern Flicker  7
Blue Jay  1
Black-billed Magpie  3
American Crow  4
Black-capped Chickadee  8
Ruby-crowned Kinglet  1
Red-breasted Nuthatch  2
House Finch  14
Dark-eyed Junco (Oregon)  1
Red-winged Blackbird  4

Milavec Reservoir, Jan 11, 2020–with Jamie Simo

Cackling Goose (left) vs Canada Goose (right) (c) Jamie Simo

Milavec Reservoir in Frederick, CO is one of the best places along the Front Range to see all the possible (read: non-rare) interior goose species. Sometimes, like last year, it even plays host to some rarities like the Colorado-record Pink-footed Goose and Barnacle Goose. As hoped for, while we didn’t see any Colorado-record geese on this frigid, but sunny, Saturday morning, we did see all the usual goose suspects. We also had some great ducks and raptors.

Nearly all Coloradans are familiar with our only breeding goose species, the Canada Goose, but winter brings migrant Cackling, Greater White-fronted, Ross’s, and Snow Geese from the arctic to our lakes, reservoirs, and fields. The most similar to the Canada Goose, the Cackling Goose was only recognized as a species in its own right in 2004. There are 4 subspecies of Cackling Goose varying in size and color, but some of the common characteristics include smaller body size than the majority of Canada Geese (there may be some overlap with the smallest subspecies of Canada Goose), a shorter neck, and a bill that looks “stubby” because of a more rounded or square head shape. Because of the difficulty of distinguishing between the smallest subspecies of Canada Goose and the largest subspecies of Cackling Goose, small white-cheeked geese are sometimes referred to as “Cackling-ish.”

Ross’s Goose (foreground) vs Snow Goose (background) (c) Jamie Simo

Like the Canada Goose, the Snow Goose also has a “mini-me” doppleganger, the Ross’s Goose, but that doppleganger is much easier to pick out than the Cackling Goose. Firstly, Snow Geese come in either the expected white plumage with black wingtips or a darker, grey-blue body plumage with white head and neck. Both have pink bills and feet as adults. The latter is sometimes referred to as a “blue goose, “blue morph,” or “blue phase” Snow Goose. There are only 2 subspecies of Snow Goose, but both have a black “grin patch” that gives them a sneering appearance, and a sloping forehead. By contrast, the Ross’s Goose, which is usually white but also occurs rarely in a blue phase, has a steep forehead leading to a rounded crown and lacks the grin patch.

The final expected goose species in Colorado is the Greater White-fronted Goose. This goose is mostly brownish-grey with darker belly bands, orange legs and bill, and white feathers around the base of the bill from which is gets its name.

Other stand-out species were 2 adult Bald Eagles, a Northern Harrier, a Red-breasted Merganser, a female Canvasback, and even a coyote. Not bad for a cold, January morning!

Female Northern Harrier (c) Chris Friedman

Frederick Lake (Milavec Reservoir) & Recreation Area, Jan 11, 2020
25 species

8 Snow Goose
3 Ross’s Goose
1 Greater White-fronted Goose
2000 Cackling Goose
4000 Canada Goose
60 Northern Shoveler
10 Mallard
1 Canvasback
7 Lesser Scaup
3 Bufflehead
20 Common Goldeneye
7 Common Merganser
1 Red-breasted Merganser
1 Ruddy Duck
3 American Coot
1 Northern Harrier
2 Bald Eagle
1 Red-tailed Hawk
1 American Kestrel
1 Blue Jay
6 European Starling
6 American Tree Sparrow
1 White-crowned Sparrow (Gambel’s)
2 Song Sparrow
1 Red-winged Blackbird

Harriman Lake, Jan 4 – with Chuck Aid

Rough-legged Hawk topography (c) Bill Schmoker

Nice mild weather prevailed on Saturday as we enjoyed a 1.6-mile stroll around Harriman Lake.  It was more than half frozen over, but that was perfect as it concentrated all the ducks a bit more and provided a nice shelf of ice for a local immature Bald Eagle.  In order to talk a bit more about plumages of Bald Eagles we need to learn a bit more about bird topography.  If you will look at the diagram, you can see that the coverts are the smaller feathers that cover the bases of the larger flight feathers – the primaries and secondaries.  There are upper-wing coverts and underwing coverts.  There are also upper and lower tail coverts that cover the bases of the main flight feathers in the tail.  I’ve labeled two other parts because they can be important terms for the identification of other raptors.  The carpal is the “wrist” of the bird, and some birds, such as the Rough-legged Hawk in this photo have a distinct carpal patch.  The patagium is the leading edge of the wing, and this can be important because to varying degrees all Red-tailed Hawks have a dark patagium.

Bald Eagle – 2nd year (c) Bill Schmoker

So, back to our Bald Eagle. It takes Bald Eagles five years to obtain their full adult plumage with the white head and tail.  During their first year they have dark brown eyes, a dark bill, and are mostly brownish overall.  During subsequent years the eyes become light brown and eventually yellow, the bill too becomes increasingly yellow.  The plumage during the intermediate years can be quite variable but tends toward a brown and white mish-mash.  For example, a first-year bird tends to have a brown belly with white underwing coverts; most second-year birds develop a white belly with extensive white underwing coverts and some white in the underwing secondaries and tail; third-year birds tend to have darker bellies than second-year birds and the underwings, while still having some white blotchiness, are darker; fourth-year birds are tending towards full adulthood with a blackish-brown belly having some white flecking, and the hood and tail are mostly white but not completely. Our bird on Saturday was a second-year Bald Eagle, much like the bird in the photo but with more white above the eye. To cut to the chase, second-year birds have more white on the body and underwings than any other year.

Best of luck with all your upcoming raptor identifications!

Chuck

 

Harriman Lake, Jan 4, 2020
26 species

Canada Goose  125
American Wigeon  12
Mallard  7
Canvasback  2
Redhead  44
Ring-necked Duck  1
Lesser Scaup  2
Bufflehead  6
Common Goldeneye  4
Hooded Merganser  15
Common Merganser  1
Pied-billed Grebe  4
Eurasian Collared-Dove  1
American Coot  160
Ring-billed Gull  3
Bald Eagle  2 (1 adult and 1 2nd-year)
Red-tailed Hawk  2
Northern Flicker  4
Blue Jay  7
Black-billed Magpie  6
American Crow  4
Common Raven  1
Black-capped Chickadee  2
European Starling  7
Song Sparrow  3
Red-winged Blackbird  40

South Platte Park, Dec 7 – with Chuck Aid

Common Mwergansers (c) Bill Schmoker

On Saturday we visited two main destinations.  We started at South Platte Reservoir, famous in the local birding community for having a county line bisect it thus providing a potential opportunity to see whatever waterfowl are present in both Jefferson and Arapahoe Counties – that is if said waterfowl cooperate and swim from one side of the reservoir to the other. County listing has become quite the recreational sport, and instead of just “seeing” birds, the focus is to “get” them, i.e. be able to enter them on a specific list or lists (county, state, country, month, year, etc.).  A few of us don’t play this game as vigorously as others.  Our second destination was the four “lakes” (AKA old gravel pits) immediately north of C-470 along the South Platte River – Blackrock, Eaglewatch, Redtail, and Bufflehead Lakes.  This general area is a favorite destination and often has great birds.

Long-tailed Duck – female (c) Bill Schmoker

We had two uncommon sightings from the dike surrounding South Platte Reservoir.  First, a pair of Long-tailed Ducks was seen, but only at a distance so the views were not great.  This duck was formerly known as Oldsquaw in North America, but in 2000 the American Ornithologists’ Union changed the name to Long-tailed Duck, the name by which it is known in Europe.  It is primarily circumboreal in its distribution, breeding in the arctic, but with a few wandering south to the lower forty-eight each winter, primarily to New England and the Great Lakes region, but we’re fortunate to get some here in Colorado.

Harlan’s Red-tailed Hawk (c) Bill Schmoker

Our second good sighting from up on the dike was of a Harlan’s Red-tailed Hawk.  There are about 12 subspecies of Red-tails, adding a lot of fun to trying to properly identify them.  Harlan’s is among the darkest of these subspecies, being primarily black with a dusky white tail that lacks any hint of red.  They have a characteristic white streaking on the breast that can be helpful in their identification.  One of the real keys when seeing a bird in flight, as we did, is to be able to first identify it as a Red-tail, and its overall silhouette is a major key.  Red-tails, compared to other soaring hawks (the Buteos) are stocky, broad-winged even out to the tips of their wings (not pointed), and a real key is that they have bulging secondaries – that is the wing is widest where the secondary feathers are.  Once you have narrowed your soaring hawk down to it being a Red-tail, then you can start tuning in to which subspecies it might be.  One interesting aspect of Harlan’s is that about 99% of them are dark morph.  Almost all the other subspecies are only about 10% dark morph.  Get your field guides out and see if you can see what I’m talking about here.  Locally, our most common Red-tail is the light morph of the Western subspecies (Buteo jamaicensis calurus), noted for its pale breast, streaked belly band, white spotting on its scapulars, dark head, dark chin, and adults with a red tail. Finally, one last characteristic to be aware of is that ALLRed-tails have a dark patagial bar – the leading edge of the wing.  It’s less obvious in some subspecies than others, but it’s there.

Marsh Wren (c) Bill Schmoker

Our third great bird of the morning was a Marsh Wren.  These wrens breed in cattail marshes and have been recorded every month of the year in Colorado, though they are more uncommon in winter.  Their pattern of residency is a bit of a puzzle: some marshes have breeders, many evidently suitable marshes never have breeders, other marshes only have Marsh Wrens in the winter, and other sites have birds all year long.  Here’s a gross generalization – Most large marshes which tend to remain unfrozen throughout the winter generally will have some wintering populations, but there are no guarantees.

Hope you are planning on having fun participating in one of Colorado’s fifty Christmas Bird Counts!

Chuck

 

South Platte Park, Dec 7, 2019

31 species

Canada Goose                          7
Northern Shoveler 460
Gadwall   18
Mallard   14
Green-winged Teal     4
Ring-necked Duck   18
Lesser Scaup   11
Long-tailed Duck     2
Bufflehead   38
Common Goldeneye   25
Hooded Merganser   31
Common Merganser   12
Ruddy Duck   13
Pied-billed Grebe     2
Eared Grebe     1
Rock Pigeon   18
American Coot   15
Ring-billed Gull   15
Bald Eagle     1
Red-tailed Hawk                            2
Harlan’s Red-tailed Haw     1
Belted Kingfisher     3
Downy Woodpecker     1
Northern Flicker     3
American Kestrel     1
Blue Jay     1
Black-billed Magpie     1
American Crow     2
Marsh Wren     1
European Starling     1
American Robin     1
American Goldfinch     1

 

Boulder Reservoir, November 9, 2019–with Aidan Coohill

Female Ruddy Duck (c) Jamie Simo

We started our walk at Boulder Reservoir with excellent sunny weather and low wind, allowing us to see the birds on the lake quite easily without many waves. Boulder Reservoir is the largest reservoir in the county in terms of both size and volume creating an excellent environment for birds but also for recreational boating, fishing, swimming, and jogging. It also provides and holds all water for the Northern Water Distinct for drinking and irrigation. We covered the area in two sections, the first on the southwestern shore of the reservoir which is extremely popular in summer for recreation, and the northern section from the West Reservoir Trailhead. 

Immediately after parking we found a large group of American coots feeding in the shallows of the swim beach. Among the flock was a lone female Ruddy duck. Belonging to the genus of “Stiff-tailed ducks”, it is a small freshwater fowl with a large range across North America. Like all in its genus, the Ruddy duck has a stiff tail (often described as looking like a bundle of Popsicle sticks), males have a bright blue bill, and a body that depending on season and sex is rusty to brown in color. These birds are currently in the process of moving to their warmer wintering grounds further south in the Unites States and into Northern Mexico. 

Bonaparte’s Gull (c) Jamie Simo

Further down the shoreline we found the Rusty blackbirds that have been seen in the area for the last several days, a rarity that drew many local birders to the reservoir. This blackbird is very similar to the Brewer’s blackbird that is common in Colorado but is an uncommon accidental migrant in this part of the west. Unlike the Brewer’s blackbird, it prefers quiet spruce forest and boreal bog and not parks, fields, pastures, lawns, and parking lots. During winter the differences between the sister species becomes most obvious with both the male and female getting buffy and ruddy patterning on their bodies. This was the state the pair we saw were in. 

On the north side of the reservoir we got another cool sighting, two Bonaparte’s gulls. This small bird is the smallest gull in North America aside from the elusive Little gull. They have dainty pink feet, a small beak, and off-white coloring. During winter plumage (what we saw) it trades its distinctive black hood for white save for a small black patch over the ear. These gulls are a real treat as they head south for the winter. 

Other highlights included a Ferruginous hawk perched in a tree on our way out, a pair of Northern harriers, and all three species of mergansers!

In all, we heard or saw 28 taxa; good for this time of year at the reservoir! 

Boulder Reservoir, November 9, 2019
27 Species (+1 additional taxa)
  • Cackling Goose 250
  • Canada Goose 100
  • Gadwall 2
  • Mallard 2
  • Lesser Scaup 1 
  • Common Goldeneye 8
  • Hooded Merganser 15
  • Common Merganser 8
  • Red-breasted Merganser 6
  • Ruddy Duck 1
  • Horned Grebe 1
  • Western Grebe 6
  • American Coot 80
  • Bonaparte’s Gull 2
  • Ring-billed Gull 200
  • Herring Gull 1
  • Great Blue Heron 1
  • Northern Harrier 2
  • Red-tailed Hawk 3
  • Red-tailed Hawk (Harlan’s) 1
  • Ferruginous Hawk 1
  • Blue Jay 1
  • Black-billed Magpie 2
  • Black-capped Chickadee 2
  • European Starling 100
  • House Finch 4
  • Red-winged Blackbird 1
  • Rusty Blackbird 2

If anyone would like me to share the eBird checklist with them please email me at aidan@coohill.com

Wheat Ridge Greenbelt, Nov 2, 2019 – with Chuck Aid

Great Horned Owl (c) Jeff Jaacks

Okay, here’s the good news! Breeding season has started! Wahoo!  The probable evidence for this was seen on Saturday as we viewed a cozy pair of Great Horned Owls exhibiting some fondness for one another’s company.  Great Horned Owls can maintain their pair-bond year-round, but these two were perched so close to one another that it felt as though an even greater increased intimacy was in the air.  We also know that copulation has been observed elsewhere in Colorado as early as November (pers. com. Rob Raker), and that incubation can start in January.  December can be a great time to hear dueting males and females – the male, though about 10% smaller than the female, has the deeper hoot (listen below).  So, make sure to step outside on a brisk December night and see if you can hear anything.

Cackling and Canada Geese (c) Bill Schmoker

So, other than owls, we had some great waterbirds.  Cackling Geese, the diminutive cousin of the Canada Goose, were in abundance.  These guys breed in the far northern Arctic and then winter throughout the southern Great Plains, including eastern Colorado. They are very similar to Canada Geese, but distinguished by their smaller size (some hardly bigger than a Mallard), relatively short neck, and stubbier bill.  This is not an easy distinction to make, and I struggle with it yearly.  We, also, had eight duck species, and spent quite a bit of time working on the finer points of duck identification.

Virginia Rail (c) Bill Schmoker

A real highlight was getting to SEE both a Wilson’s Snipe and a pair of Virginia Rail.  Both of these species occur year-round in Colorado, though the rail, in particular, is uncommon in winter.  We saw the Wilson’s Snipe in flight, noting its twisting, zig-zag flight, and very long bill.  Only a few minutes later, we had two Virginia Rail pop out briefly from some dense cattails about eight feet in front of us, and then they were gone in an instant.  A third one was heard in a different spot. Pretty special to see both of these species on the same outing!

Finally, we had a good variety of songbirds.

Hope to see you on another walk soon!
Chuck

Wheat Ridge Greenbelt, Nov 2, 2019
38 species

Cackling Goose  180
Canada Goose  50
Northern Shoveler  32
Gadwall  22
Mallard  35
Green-winged Teal  2
Bufflehead  14
Common Goldeneye  8
Hooded Merganser  24
Ruddy Duck  2
Rock Pigeon (Feral Pigeon)  6
Virginia Rail  3     
American Coot  14
Wilson’s Snipe  1
Ring-billed Gull  46
Cooper’s Hawk  1
Red-tailed Hawk  1
Great Horned Owl  2
Belted Kingfisher  3
Downy Woodpecker  1
Northern Flicker  7
Blue Jay  6
Black-billed Magpie  11
American Crow  8
Common Raven  2
Black-capped Chickadee  16
White-breasted Nuthatch  3
Brown Creeper  1
European Starling  7
American Robin  2
House Finch  10
American Goldfinch  12
American Tree Sparrow  6
Dark-eyed Junco  1
White-crowned Sparrow  5
Song Sparrow  10
Spotted Towhee  2
Red-winged Blackbird  9