In February 2020, we trapped a very interesting dark bird north of Atchison, Kansas. We were targeting dark non-harlani for our transmitter effort to track these birds to their breeding grounds as a first step for understanding if the subspecies abieticola is polymorphic.
At first pass this bird looked like our target, but when we extracted it we immediately saw the multiple harlani traits throughout the birds plumage. After later successfully trapping our targets, I came back to photos of this bird for comparison and recognized the similarities in traits, which led me to the conclusion that this interesting dark bird is likely an intergrade between harlani and the dark birds that we outfitted with transmitters (we are calling these abieticola, which might be an oversimplification, but we’re working on it!)
Below I’ve included a figure that compares a dark harlani (top) that I trapped with Neil Paprocki, Caitlin Davis, and Johnna Eilers in Northern Idaho in November 2019, the interesting intergrade (middle), and one of our transmitter birds (bottom). I also included photos of the tails of each to allow more detailed comparison between the three.
Red-tailed Hawk Project 