Dark morphs tagged in Kansas breed in sympatry with harlani

Most of our birds are back on the grid as they finish their fall migration. As a result, we have breeding locations to share – perhaps the most exciting of which are the dark putative ‘non-harlani‘ birds.

Below are the breeding locations for the remainder of our tagged harlani, as well as individuals we tagged in Kansas last winter as an effort to better understand the breeding origin of dark birds wintering in the Great Plains.

harlani
‘non-harlani

Unfortunately, the third dark morph we tagged last winter is the one bird we have not heard from yet this fall. But, we last received locations when it was headed into Alaska, so we can be reasonably sure it is a breeder from that area.

As you can see, the dark birds we tagged that lack typical harlani characteristics, including the first two birds in our study, breed in sympatry with harlani. This is exciting, but not entirely unexpected. We knew before that these types breed in Alaska from our observations at Gunsight Mountain, Alaska during spring migration (Check out this collection of photographs), and from observations on the breeding grounds (see Bryce’s observations near Anchorage), and a bird very similar to Hathor that Rob Domenech tagged that bred near Wasilla, AK.

Does this mean they are harlani? Or are they intergrades? If so, intergrades between which taxa? Or is the explanation much more complicated? These are unanswerable questions at the moment, but luckily we have the blood samples to do genomic work that should help us understand things. No matter what the explanation, it is sure to be interesting.

There are many plumage characteristics that separate these dark birds from what we consider typical harlani plumage. Perhaps the most striking is the tail, as you can see in the image above that illustrates the diversity in tail plumage that can be found in Red-tailed Hawks breeding in this area of North America. If these are all part of the same subspecies, harlani, then it increases the phenotypic diversity in this taxon to an incredible degree. In that case, it begs the question of why and how such diversity is maintained in this population, and not others. To help understand this, we plan to add more samples to see if this pattern holds, and to start digging into genomic data for the samples we already have. Some exciting stuff ahead, so keep checking in for more updates.

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