Tuesday, December 7, 2010

Coops of Cooper's Hawks

In my previous post I teased a comparison Cooper's Hawk from the weekend, well I have that and then some.

On Sunday I made a couple of stops in Boulder County, the second of which was at north Teller Lake. I had a good bird list on my walk, nothing uncommon but a great mix of species. Among them was this juvenile Cooper's Hawk. Like the bird from Friday afternoon, I suspect that this was a female. Both were noticeably large birds, and in Cooper's Hawks the female can be almost one third larger than the male. I was really happy to see a juvenile for comparison so soon after seeing the adult. The major differences to note are the vertical striping on the breast, as opposed to the horizontal barring on the adult, and the light colored irides which turn an awesome red-orange color on the adults. On the subject of which....

'Boom goes the dynamite'. Today I stopped by a nearby park and reservoir for lunch. I had neglected the spot for a few months, but was treated to this male adult Cooper's Hawk today. The park is at the edge of a development on the extension of the Davidson Mesa north of South Boulder Road, it is a small, basic park, but features views through the fence at the private Louisville Reservoir, and a step-over-fence path that runs into a much larger section of open space. Just as I was approaching the lake the Coop flew out of the backside of an evergreen, and landed up high in a Cottonwood near the water.

My first impression was that it was a small bird, and possibly a Sharp-shinned Hawk. They are even smaller still, and have a less prominent dark 'cap' on a proportionally smaller head. Being smaller than the two birds I had seen previously I was fairly confident that this was a male in the field, and closer looks at my photos after the fact strengthen that conviction. I guess when it rains it pours, and I am feeling very fortunate to have gotten three great looks at distinct individuals of this intriguing species.


  1. Those are all excellent photos of the beautiful birds! Nice going!

  2. very nice. I see a Coopers or Sharpie around here occasionally... but I still have trouble telling them apart!
    - The Equestrian Vagabond