Posted by Bob Lefebvre
Recently Terry Korolyk spotted an interesting hawk on Hwy 549 just west of Hwy 773, south of Calgary. Terry says it is an intergrade Harlan’s light phase Red-tailed Hawk.
Terry says:
Thought some Birds Calgary viewers might like to see what this bird looked like. The underparts are obviously a mix of both subspecies. The underside of the tail is obviously white with duskiness near the tip. The upperside of the tail was, in reality, white with a reddish subterminal band and 2 narrower wavy reddish bands adjacent to that.
Photographed by Terry Korolyk on April 6, 2012. Click to enlarge.
To fully appreciate the bird in the photo, look at images of adult Harlan’s Hawks and of adult Eastern Red-tails, then look at my bird again. Rather than blackish underparts with a white streaked throat like a Harlan’s Hawk, or, rather than having white underparts with a strongly streaked belly like an Eastern Red-tail, you have a bird with underparts markings that meet in between. The upperparts are clearly blackish like a Harlan’s Hawk, but they also have that Eastern Red-tail brownish cast. The tail was white like a Harlan’s Hawk, but, rather than having a dusky tip, it had 3 narrow wavy reddish lines there indicating normal light-phase Eastern Red-tail association.
As Terry says, the usual Red-tailed Hawks here are the Eastern subspecies, and “Harlan’s” Hawks are considered to be another subspecies of Red-tailed Hawk. At one time, Harlan’s Hawk was considered to be a separate species entirely. Intergrades like the one above indicate that they are varieties of one species (many people believe that Harlan’s is a separate species; perhaps genetic testing will settle this question).
The Harlan’s Hawk is very different from all other Red-tailed Hawk subspecies. In both its dark and light forms it has black and white plumage, lacking the reds and browns of other Red-tails. The tail, however, can have a wide variety of patterns. Harlan’s Hawk breeds in Alaska and northwestern Canada and winters on the southern great plains. We see them occasionally in Calgary in the winter months, when most other Red-tailed Hawks are absent.
We are at Westcott, about 35 minutes north of Calgary. I see up to 7, repeatedly on my drive north, and I believe we have a pair that appear to be resident here/near our property. I have seen two pairs and 3 singles on the drive along SH 766. The bird that frequents our place has a definite red to the bottom of the tail feathers, and mostly a grey (barred) chest. He has been named “Hudson”.
One of the hawks just south has a orange collar at the top of the chest. Very distinct, but I did not get a look at the tail feathers. I have just started to carry my camera with a 200mm lens, so I hope to be able to get some decent close up photos, and have a good look at these fantastic guys.
Robert Angel
This is a dark-morph adult Harlan’s, not a light-morph.
I think the title I put on the post is misleading. Terry is saying that this is a cross between a Light-phase Red-tailed Hawk, and a Harlan’s Hawk, which is the darkest morph. I should have titled it “Harlan’s/Light-phase Red-tailed Hawk” (now changed).