After scouting out Pella Crossing the day before on a very chilly and overcast Friday morning, it was a blessing to wake up to such a sunny, beautiful day on Saturday. Unsurprisingly, the majority of activity at Pella was at Webster Pond, which is set aside as an emergent wetland for native fish and is therefore closed to fishing. The pond held 11 different species of duck.
Right away we spotted both Canvasback and Redhead ducks, which are two diving ducks sometimes confused for each other. Males of both species have reddish heads in breeding plumage, but while Redheads have conventional round heads, Canvasbacks are easily distinguished by their “ski slope-like” foreheads, which make their profile very triangular.
Among other diving ducks seen were Lesser Scaup and Ring-necked Duck, which are also often confused for each other. While males of both species sport black heads which shine iridescent in the right light, Lesser Scaup males have grey backs with whiter flanks. Ring-necked Duck males, however, have black backs and greyer flanks with a white vertical “spur” at the shoulder area. If close enough, you can also see that Ring-necked Ducks have ringed bills while Lesser Scaups lack this feature.
Although it’s still a little early for spring migration, we did witness several hints of spring. We saw several Hooded Merganser males, which are a type of fish-eating duck, exhibit courtship behavior, puffing up their crests and stretching their necks out for the accompanying females.
Across the agricultural field to the south we also witnessed a Red-tailed Hawk bringing sticks to a nest. Such “nestorations” are a prelude to breeding and egg-laying, which may begin as early as later this month for this species. While songbirds were in short supply due most likely to the breeze, we did also see two other raptor species: two soaring immature Bald Eagles and, making its appearance just before reaching the parking lot at the end of the walk, an adult Cooper’s Hawk.
All-in-all we saw 28 species, which wasn’t bad for the “calm before the storm” of spring migration!
Pella Crossing Open Space, Boulder, Colorado, US 28 species
Cackling Goose 40 Canada Goose 100 Wood Duck 2 Quick fly over. Heard alarm call from female and saw two ducks. Gadwall 11 American Wigeon 6 Mallard 6 Green-winged Teal 2 Canvasback 2 Redhead 3 Ring-necked Duck 1 Lesser Scaup 5 Bufflehead 3 Common Goldeneye 5 Hooded Merganser 8 Rock Pigeon (Feral Pigeon) 5 American Coot 1 Cooper’s Hawk 1 Bald Eagle 2 Red-tailed Hawk 2 Belted Kingfisher 1 Northern Flicker 1 Common Raven 2 American Robin 2 House Finch 4 American Goldfinch 1 White-crowned Sparrow 2 Song Sparrow 2 Red-winged Blackbird 6
Pella Crossing Open Space encompasses a collection of former gravel-mine ponds to both the east and west of N 75th Street in Hygiene, Colorado. The portion of the open space west of N 75th Street also includes a short stretch of Saint Vrain Creek on its way to Longmont. The water features and riparian habitat attract many interesting bird species at all times of year. We were greeted by a calm and bright spring morning for our May 14, 2022 second Saturday bird outing to the Marlatt Trails on the western portion of Pella Crossing Open Space.
Spring migration and the beginning of the breeding season was already in full swing at Pella Crossing. Many of the northern Front Range resident species were beginning to start their annual breeding rituals, with Red-winged Blackbird males vigorously chasing females, House Finches carrying nesting material, courtship feeding between a pair of Black-capped Chickadees, and a female American Robin already incubating on a nest. Two pairs of Osprey, which migrate here to breed from points south, occupied two separate nest platforms at opposite ends of the western half of Pella Crossing, both females incubating and one of the males continuing to bring nesting material. The Great Blue Heron rookery next to Saint Vrain Creek sounded active, which is to say that we heard Great Blue Herons in that direction, but we could not see birds at nests because the trees were already leafing out.
The real stars of the day’s show, however, were the summer breeders who winter far to the south of Colorado, and the spring migrants visiting briefly on their way to breeding grounds in points north or in higher elevations. A number of northern Front Range summer-visiting songbirds like House Wrens, Gray Catbirds, Bullock’s Orioles, Yellow Warblers, and four species of swallows (Tree, Barn, Cliff, and Northern Rough-winged) delighted us with their cheerful songs and bright colors. A few species were just passing through, still yet to reach their breeding grounds. Among them, a skulky Lincoln’s Sparrow giving its buzzy call, a flamboyant male Western Tanager, and a handsome male MacGillivray’s Warbler (whose name, the group decided, is a mouthful to say!).
Speaking of warblers, two of the biggest highlights of the day were undoubtedly warblers. First, the aforementioned MacGillivray’s Warbler (say it again with me!), which we stayed on for several minutes as it furtively fed along a stand of Russian Olives until everyone in the group got a definitive look – which is saying something indeed for a small, busy, and camouflaged bird uninterested in showing off! The second fabulous warbler we saw was a female-type Northern Parula, which is an unusual sight in our area, as the bulk of their migration path falls far to the east of Colorado’s eastern border with Kansas. This bird was fairly dull-colored even for a female Northern Parula, and may have been a first-year female hatched last summer, now making her first northward migration.
We had a fun group of birders brimming with enthusiasm on our May 14th outing – I thoroughly enjoyed sharing the morning and the birds with you all. My only regret is that with all the interesting birds popping up all around, I didn’t have enough time to answer all your questions and continue all the conversations! Please drop Front Range Birding Company a line at boulder@frontrangebirding.com if you still have burning questions – we touched on a lot of topics like species concepts, hybrids and intergrades, status and distribution of many bird species, and distinguishing between similar species. One of my favorite birds to share with you (and one which spoke to all of those aforementioned topics) was a male Northern Flicker that showed characteristics of being an intergrade between the western “Red-shafted” form and the eastern “Yellow-shafted” form. The two forms are so visually different that they were once considered separate species. On the Front Range of Colorado, the two forms meet and produce an intergrade zone of Northern Flickers that display a spectrum of plumage traits from both forms. Our particular male flicker was a textbook example of such an intergrade, with a bright red malar stripe (“mustache”) from its red-shafted ancestors, and a red nuchal/nape patch on the back of the head from its yellow-shafted ancestors. These intergrade Northern Flickers remind us to look closely at even the most common birds around us – they can be just as fascinating as the rare birds that show up during migration seasons!
See you next time – let’s go birding!
–Sarah
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36 species observed, 188 individuals
Canada Goose (Branta canadensis) 8
Mallard (Anas platyrhynchos) 1
Eurasian Collared-Dove (Streptopelia decaocto) 2
Mourning Dove (Zenaida macroura) 1
Double-crested Cormorant (Nannopterum auritum) 10
American White Pelican (Pelecanus erythrorhynchos) 1
Great Blue Heron (Ardea herodias) 5
Turkey Vulture (Cathartes aura) 5
Osprey (Pandion haliaetus) 4
Bald Eagle (Haliaeetus leucocephalus) 1
Northern Flicker (Yellow-shafted x Red-shafted) (Colaptes auratus luteus x cafer) 1