Monday 9 December 2013

Red-tailed Hawks in B.C.'s Southern Interior.

Red-tailed Hawks in B.C.'s Interior

1. What constitutes usual versus unusual plumage? 

Figure 1 - RTHA - light morph white-chested adult with medium belly band. Photo taken in Nov. 2013, courtesy of Rick Howie.

Things to consider when describing a Red-tailed Hawk:
1. colour of chest
2. colour of chin
3. extent and darkness of the belly band
4. colour of upperparts
5. presence and extent of pale scapular patch
6. eye colour
7. background colour of uppersurface of the tail
8. presence or absence of a broad band on the trailing edge of the wing.
9. presence of patagial mark

 I would consider the Red-tailed Hawk in Figure 1 to be quite typical for many Red-tails in the southern interior of B.C. A variation on this basic light morph-light chest theme is shown in Figure 2. 

Figure 2 Adult light morph Red-tailed Hawk, Kamloops area. Buffy chested with medium belly band. Photo courtesy of Rick Howie.

Most of our local adult Red-tails have tawny or white breasts. However adults with brick-red breasts, dull brown breasts, and brown and white streaked breasts do occur.

The majority of our light morph adults show belly bands made up of dark feathers lined vertically across the birds' lower undersides. Across the spectrum of red-tail types belly bands can range absent to completely black. Brian Wheeler, famed raptor expert, writes that a belly band is characteristic of the Western Red-tailed Hawk, Buteo jamaicensis calurus.

Here are three examples of fairly typical western type Red-tails with different belly bands:

Three RTHAs photographed northwest of Swan Lake, N. Okanagan, 4 Dec 2013 by CS. 


Now for a very unusual plumage seen recently in the Kamloops area.

Check out the bird in Figure 3. This bird looks much like an eastern Red-tailed Hawk, Buteo jamaicensis borealis, but was photographed in November 2013 in the Kamloops area by Rick Howie.
Notice the single subterminal tail band, the white throat (as opposed to the bird in Figure 2), and the delicate belly band. What a stunner!

Figure 3 - Rick's eastern type RTHA, Kamloops area, Nov. 2013

Figure 4 also shows this same bird.

Figure 4 - Rick's eastern type RTHA- another view


Contrast this bird with the hawk in Figure 1. With the kind of variation by our Red-tails, it's little wonder that beginning birders have trouble identifying hawks. 


2. More images to ponder: what follows is a gallery of Red-tailed Hawks photographed locally. Consider the effects that age, morph or "colour phase" molt and fading play in producing the huge variety of Red-tailed Hawk plumages we see in our study area.

Figure 5 - A dark morph adult RTHA at Westwold, 21 Nov. 2013. Photo by Chris Siddle
Figure 6 - a black RTHA, possibly a Harlan's Hawk. Douglas Lake, 21 Nov. 2013.

Figure 7 - This RTHA lived around the base of Silver Star Mountain during the spring and summer of 2013. It appeared to be an intermediate morph with a very poorly defined belly band. However, it was the apparent general faded aspect of this individual that set it apart. It was paired with a "normal" light morph adult. Mid August 2013. Ph - C S.








Figure 9 - A RTHA adult, judging by the broad band on the trailing edge of the wings, in molty plumage, especially the tail. Vernon, August, 2013. Ph - CS.  


Figure 8 - Note the poorly developed, narrow band along the trailing edge of the wing. This is characteristic of an immature as are the light eyes. An adult shows a dark broad trailing edge as in Figure 5. Okanagan Landing, 11 Nov. 2013. Photo by Chris Siddle.


                                                                                                                                         
     
Any comments? Please email your comments to chris.siddle@gmail.com.