Author: frbcadmin

Golden Banner (c) Chuck Aid

A spring morning at Roxborough is pretty hard to beat. The wild plums were all in bloom and subtly perfuming the air.  Many of the early flowers were out: Sand Lily, Mertensia (Bluebells), Larkspur, Golden Banner, Spring Beauty, Oregon Grape, etc.  And, there were the usual resident birds mixing with the newly arrived migrants.

Prairie Falcon (c) Rob Raker

Of course, the main attraction at Roxborough are the incredible rock formations, and it is always of interest to tune in to the birds that utilize this unique habitat.  For the last several years Prairie Falcons have nested up on the highest protected rock ledges where they scape loose pebbles to form a small depression to hold their eggs.  And we got to watch a single falcon standing up high on its ledge.

White-throated Swift (c) Bill Schmoker

Also, notable were the Violet-green Swallows and White-throated Swifts that utilize the numerous little pockets and cracks in the faces of the cliffs for their nests.  A little bit of info on swifts and swallows.  Swifts, along with Hummingbirds, belong to the order Apodiformes (“without feet” or “footless”) because their feet are so little and really only useful for perching.  Swifts superficially resemble swallows, and both groups get their groceries by foraging for flying insects.  However, swifts are faster flying, with a rapid, flickering flight reminiscent of bats, they rarely fly in a straight line – giving the impression that their wings are flapping alternately, their sickle-shaped wings are more swept back, and their “wrist” appears proportionally closer to the body.

Violet-green Swallow (c) Rob Raker

Swallows are in the large Passeriformes order – “Perching” birds – which includes over half the birds in the world.  They have broader, shorter wings, and have a more relaxed wing-beat.  Both the species we were seeing, White-throated Swift and Violet-green Swallow, have rumps with white sides, so this can take a bit of work sorting these out.

Other birds that can, at times, have a preference for foraging on cliff faces include Northern Flickers and Say’s Phoebes, but we did not see any of this behavior this time around.

Cooper’s Hawk (c) Rob Raker

Perhaps the real highlight of the day was getting to play bird detective a bit with a pair of Cooper’s Hawks.  Being woodland hawks, often in dense foliage where visual contact may be limited, they rely on vocalizations as a primary means of communication.  We first heard a single bird making a couple of interesting sounds down in the little riparian area below our trail.  One call was the typical “cak-cak-cak,” which, once one becomes familiar with it, is fairly distinct, and provides an easy way to identify a “Coop.”  The other call, however, was not one with which I am familiar, a kind of nasal “whaaa.”  A little research indicates that this is primarily a call that females make that’s related to receiving food, or begging for food, from the male.  Digging a bit deeper I found that scientists have identified 42 different calls by females, 22 by males, and 14 by young. The larger repertoire of calls by females is attributed to their greater need to convey more information.

So, then, after a bit of looking we located our calling bird, presumably a female, in the upper branches of a cottonwood.  Shortly thereafter the male showed up, and they were alternately engaged in sitting in a nearby stick nest, presumably getting it in shape for the eventual laying of eggs. The longer we stood up on our trail, and just observed things, the more we saw and learned.  Great fun!

Hope to see you soon on another bird walk!

Chuck

Roxborough SP, May 4, 2019
24 species (+2 other taxa)

Mourning Dove  1
White-throated Swift  7
Broad-tailed Hummingbird  12
Turkey Vulture  2
Cooper’s Hawk  2
Red-tailed Hawk  1
Prairie Falcon  1
Say’s Phoebe  2
Woodhouse’s Scrub-Jay  1
American Crow  2
Violet-green Swallow  15
Black-capped Chickadee  8
White-breasted Nuthatch  2
House Wren  3
Ruby-crowned Kinglet  1
Townsend’s Solitaire  1
Lesser Goldfinch  1
Chipping Sparrow  1
Spotted Towhee  21
Western Meadowlark  1
Red-winged Blackbird  1
Brown-headed Cowbird  1
Yellow-rumped Warbler  4
Yellow-rumped Warbler (Myrtle)  1
Yellow-rumped Warbler (Audubon’s)  2
Lazuli Bunting  2

How delightful to finally be getting a few Spring-like days! We had such an enjoyable stroll through the DBG at Chatfield on Saturday morning. Lots of singing going on, and a profusion of green leaves emerging everywhere.

Turkey Vulture (c) Bill Schmoker

So, part of what we did not see was a big variety, or large numbers, of waterfowl. Many species will be heading north shortly, and some have begun to do so already, but there should still be good representation by just about all of our wintering ducks. We just fell a bit short of what I anticipated we would see. We, also, did not see a few of the migrant species that are on the verge of arriving from the south. Marsh Wrens and Swainson’s Hawks have just started appearing in the area, but we saw none. Other species, such as Blue Grosbeaks and Bullock’s Orioles, are really not expected to show up for another three to four weeks.

Bald Eagle (c) Bill Schmoker

So, what did we see? Well, we did well in the raptor department seeing a few soaring Turkey Vultures, both Golden and Bald Eagles, a Cooper’s Hawk visiting a possible nest site, a couple of Red-tailed Hawks, an active Great Horned Owl nest with mom and three nestlings, and a single American Kestrel. We hoped for a late Ferruginous Hawk or an early Swainson’s Hawk, but had no luck.

Say’s Phoebe (c) Bill Schmoker

We had a few other nice surprises, including great looks at a pair of Eastern Phoebes. Historically, these guys were only found breeding in rimrock canyons and riparian woodlands in southeastern Colorado. However, with increasing frequency Eastern Phoebes are now being recorded breeding along the front range foothills in Jefferson, Boulder, and Larimer Counties. This pair was hanging out in low vegetation along Deer Creek, and even finding perches on small boulders adjacent to the creek. They can be identified by being somewhat larger than a Western Wood-Pewee, having a dark head, light gray vest, light yellow belly, dark tail, and a distinctive tail-wagging motion.

Tree Swallow (c) Bill Schmoker

The Say’s Phoebe is a close relative of the Eastern Phoebe, being in the same genus Sayornis, and we got to see and hear several of them. They occur in our area much more commonly, with even a few electing to spend winters here, so they are not unexpected. Swallows tend to start arriving each spring during the first part of April, and we were fortunate to see both Violet-green and Tree Swallows. We also got great looks at a few Ruby-crowned Kinglets, even getting to see the ruby crown being partially displayed on one.

And, just as an odd occurrence, we had three Common Ravens but no American Crows. Kind of the opposite from what one might expect.

Good birding!

Chuck

Denver Botanic Gardens at Chatfield, Apr 6, 2019
37 species (+1 other taxa)

Canada Goose 15
Northern Shoveler 4
Gadwall 16
Mallard 11
Common Merganser 4
Rock Pigeon (Feral Pigeon) 9
Eurasian Collared-Dove 1
American Coot 1
Killdeer 2
Ring-billed Gull 3
Turkey Vulture 3
Golden Eagle 1
Cooper’s Hawk 1
Bald Eagle 1
Red-tailed Hawk 2
Great Horned Owl 4
Downy Woodpecker 3
Northern Flicker 4
American Kestrel 1
Eastern Phoebe 2
Say’s Phoebe 4
Blue Jay 2
Black-billed Magpie 5
Common Raven 3
Tree Swallow 1
Violet-green Swallow 5
Black-capped Chickadee 5
White-breasted Nuthatch 2
Ruby-crowned Kinglet 3
American Robin 15
European Starling 9
House Finch 6
Dark-eyed Junco (Pink-sided) 1
Dark-eyed Junco (Gray-headed) 2
Song Sparrow 6
Western Meadowlark 5
Red-winged Blackbird 14
Common Grackle 2

The goal for the day was winter raptors, and the area between Barr Lake and DIA is one of the best I know of that is relatively close to the Denver metro area.  So, how do we know where we might find raptors?  Well, a key place to start is by looking at where they get their groceries. Let’s look at some of our local raptors a bit more closely.

Bald Eagle (c) Bill Schmoker

Bald Eagles eat fish almost exclusively, so it makes sense that Barr Lake always has a fair number of wintering Bald Eagles. However, if a large prairie dog town is in the vicinity of their fish market, then they may bop over there to check things out – possibly, to catch an unaware “dog,” but what can be even easier is to steal one from someone else who already did all the work, what’s known as kleptoparasitism.

Golden Eagles will eat a variety of mammals, and they will cover large distances when foraging, but perhaps because they prefer their overnight canyon roosts in the foothills they tend not to be seen regularly too far out on the eastern plains.

Ferruginous Hawk (c) Bill Schmoker

Ferruginous Hawks focus primarily on ground squirrels and prairie dogs.  This is our largest Buteo (soaring hawk), weighing up to 3.5 lbs.  In contrast, a Red-tailed Hawk weighs only 2.4 lbs.  In looking closely you’ll notice the Ferruginous’ huge bill, accentuated by its long “gape” – the portion of the mouth extending back into the head, allowing for a larger mouth opening.  Also, notice its large feet compared to other Buteos.

Ferruginous Hawk (c) Bill Schmoker

Red-tails go for a bit smaller prey, primarily voles, mice, rats, and cottontails.  Prairie Falcons in the winter focus mainly on Horned Larks and Western Meadowlarks, and Northern Harriers and American Kestrels on voles.  As for Rough-legged Hawks, the third of our three Buteos being addressed here, they weigh only slightly less than Red-tails, but they have a smaller bill and smaller feet, and their primary winter prey is also voles.

So, back to our question about where to find raptors in the winter.  We need to start by determining which of the prey “grocery stores” might be the easiest for us to find, and the answer, generally, is prairie dogs.

Rough-legged Hawk (c) Rob Raker

Black-tailed Prairie Dogs have several extensive towns in the area we chose to visit on Saturday.  However, while these dogs don’t hibernate, they do tend to snuggle down in their burrows when the weather gets a bit crisp, as it was on Saturday morning as a cold-front descended on us.  As a result, we had no dogs, and therefore very few raptors.  The potential dramas that can unfold in this area along 112^thAve are legendary, with numerous Ferruginous Hawks, Bald Eagles, Red-tails, an occasional Golden Eagle, and an occasional Rough-leg attempting to steal a dead prairie dog from one of the Ferruginous Hawks that has successfully made a kill.  We struck out this time, except for the numerous Bald Eagles and a solitary Great Horned Owl, we saw at Barr Lake, but we will keep this same itinerary on the books for a future outing.

White-crowned Sparrow – Gambel’s (c) Bill Schmoker

On a final note, let’s talk briefly about White-crowned Sparrows (Zonotrichia leucophrys).  We have two sub-species that predominate in Colorado.  The ones we saw on Saturday had orange bills, and white lores (the area between the eye and the bill).  These are the Z. l. gambelii subspecies.  The birds that we’ll see nesting up in the krumholtz next summer will have pinkish bills and black lores – the Z. l. oriantha subspecies.  Both can be seen during migration.  There will be a test next time I see you, so study up!

Good birding!  Chuck

112^thBarr Lake SP,
24 species (+2 other taxa)
Canada Goose  120
Common Merganser  40
Rock Pigeon (Feral Pigeon)  2
Eurasian Collared-Dove  5
Ring-billed Gull  7
Bald Eagle  27
Red-tailed Hawk  5
Ferruginous Hawk  2
Great Horned Owl  1
Northern Flicker  2
American Kestrel  2
Blue Jay  3
Black-billed Magpie  9
American Crow  6
Black-capped Chickadee  8
American Robin  18
European Starling  7
House Finch  5
American Goldfinch  1
Dark-eyed Junco (Slate-colored)  3
Dark-eyed Junco (Oregon)  4
Dark-eyed Junco (Pink-sided)  2
White-crowned Sparrow (Gambel’s)  9
Western Meadowlark  2
Red-winged Blackbird  37
House Sparrow  17