Sunday, March 13, 2011

Accipiter cooperii

What a beautiful near-Spring day in Boise. Karyn and I headed out to our local birding trail to see what we could see. Hull's Gulch Preserve is our favorite hotspot for its local wildlife diversity, but also because it is a nice 3-4 mile hike from our house. Saturday would be a spectacular day out there. While we would see many species, the highlight were clearly the bird courting each other in this early mating season. A pair of Belted Kingfishers appeared to be searching for nest sites and were staying in close proximity to each other, chattering non-stop. American Kestrels were performing display flights at numerous locations. We found a pair of Western Screech-Owls snuggled side by side. It was one big dating frenzy. Of course, the season as long since passed for the Great Horned Owls as the female incubates her eggs under the watchful eye of the male. But the highlight of the day would come from the medium sized Accipiter hawks - the Cooper's Hawks.

Cooper's hawks are the smaller cousin of my study species the Northern Goshawk. They are a forest raptor capable of maneuvering quickly through reasonably dense forest structure. A few years back, we discovered a new nest within the Hull's Gulch Preserve, and they have nested there ever since.

Juvenile Cooper's Hawk

Our first discovery consisted of two juvenile Cooper's Hawks near the lower pond. The juveniles have very different markings than the adults as you can easily see in these photos.

Juvenile Cooper's Hawk

For a few weeks now we have usually been able to find the adults near their old nest location. Today would be no exception. We found both the male and female hanging out together.

Male Cooper's Hawk

Male Cooper's Hawk

Female Cooper's Hawk

I started to walk away to look for other birds as I heard the two calling to each other. I turned and raised the camera to see them mating.

Mating Cooper's Hawks

After the two regained their composure, the male went to work to continue building the nest. This is a new nest this year, not far from the old nest. It appears to be a much better location, although probably closer to human disturbance.

Male in new nest.

We watched as he repetitively flew out to gather nesting material and return it to the nest. He was collecting a mixture of nesting material from different locations, sometimes flying to the ground and sometimes to nearby trees. Some twigs were fresh branches that he broke off, others were dead branches on the ground.

Male Cooper's Hawk returning to the nest.

Male Cooper's Hawk leaving nest.

Cooper's Hawk returning to nest.

Male Cooper's Hawk in nest.

Cooper's Hawk in nest.


Kah-Wai Lin said...

Nice capture!

Kah Wai

Anonymous said...

Very nice series of photos.