Dark Morph Rough-legged Hawk at RM Arsenal

[Ron Wolf]

There has been a dark morph Rough-legged Hawk (RLHA) hanging out at Rocky Mountain Arsenal National Wildlife Refuge. I saw the bird on Sunday, Jan. 22, and on each of the previous two weekends. A FWS ranger said she has been seeing this bird regularly for the last few weeks. All of the sightings have occurred on the wildlife loop road along the first quarter mile before crossing into the bison area and along the first mile inside the bison area. At first glance the perched bird might appear to be a dark morph Red-tailed Hawk, but when it takes flight the distinction becomes apparent. See photos at:

https://www.flickr.com/photos/rwolf/52570651028/

https://www.flickr.com/photos/rwolf/52570397204/


Ron Wolf
Arvada, CO

[Krista Hinman]

Ron:

This is a beautiful raptor and your photos are great. However, this is a red tailed hawk. There are patagial bars that are clear and visible (a dead give away for a red tail), as are the gray lores and faint belly band. Also, it lacks booted tarsi (seen, or rather- not seen- in the second photo), nor is the tail banded as you would expect in a rough legged hawk.

Regardless, beautiful bird- thanks for sharing your sighting and photos!

Krista Hinman

Castle Rock, CO 

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Krista Hinman

www.kristahinman.com

[aiant...@gmail.com]

Hi Ron, Krista and all.

I was studying the photographs and comparing it with images in Raptors of Western North America and Birds of Prey of the East by Brian K Wheeler and deciding exactly what to write, when I saw a reply from Krista, whom I agree with.

My wife had shown me the images this morning that you had posted. My immediate impression was that it was a Red-tailed Hawk as I could clearly see the patagial mark on the flying bird. This is pathognomonic for RTHA as no other buteo shows it.

Doing the fall count at Dinosaur Ridge Hawk Watch in 2022 as well as conducting 3 Winter Raptor Surveys for HMANA in NY for 5 years and CO this season, I realized identifying dark morph buteos is extremely difficult in CO and I have been studying the literature to distinguish them. What I found is that while the head, breast and belly can be dark – this does not affect the tail pattern, so this is what is recommended for use primarily for ID purposes. The flight feathers too retain unchanged the pattern of the species.

So if it had been a Rough-legged Hawk the tail as seen from below would have been white-based with multiple dark tail bands on a male, a single broad dark sub-terminal band on a female, and a  dusky terminal band on an immature – which we don’t see on the posted images.

The squarish black carpal patches would show up distinctly if it were a Rough-legged Hawk, even against the darkish underwing coverts (which are not too dark) in the image of the flying bird.

Even a dark morph Rough-legged Hawk would have white outer lores and forehead creating a white mask. I remember Brian K. Wheeler’s talk at DFO about 4 years ago when he emphasized that Red-tailed Hawk has pale lores, that Krista mentioned.

On a Rough-legged Hawk the bases of the primaries are dazzlingly white when seen from below. 

An additional ID feature to age the bird – the trailing edge of the wings has a distinct black border which makes it an adult bird, so also the dark eyes.

Excellent points by Krista especially about the feathering of the legs, which I hadn’t thought of. (Btw while the belly is a little darker on the perched image I don’t see a bellyband, nor do I see one on the flying bird where there is a shadow on the belly).

Ajit I Antony

Central Park, Colorado

[David Suddjian]

To take a step back, dark morph Rough-leggeds are strikingly blackish to black not brown. I like this image, even though not sharp, by Judy McKeon from a recent outing we had in South Park. 

David Suddjian

Ken Caryl Valley

Littleton, CO

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[Jared Del Rosso]

Apologies in advance if I'm wrong on this (I haven't seen a Rough-legged in years), but perhaps this iNaturalist report show a dark morph Rough-legged @ RM Arsenal? The same bird appears on at least one eBird checklist. It appears more uniformly black, without the belly-band look of the original bird. It also seems to have feathered legs. If so, then indeed a dark morph Rough-legged is around.

I'm smitten and beguiled by the variety of winter Red-tailed Hawks. (And I should spend more time with a field guide.) And I haven't yet forgotten my first encounter with a Rough-legged Hawk -- which stared me down, eating roadkill, only to be displaced by my lifer harrier, then a Red-tailed. A remarkable scene outside DIA.

- Jared Del Rosso

Centennial, CO