Great Pyrenees Dog water color painting

Mostly self taught, I consider the different mediums my teachers...Watercolor has always been the most demanding one. Only watercolor requires me to have a sense of control and at the same time the willingness to let go...

Some people go to health spas or retreats for some quiet time and self-reflection...I turn to watercolors...

This is a watercolor painting of Guardia, a 9 month old Great Pyrenees that we rescued from a puppy mill in 2008. It took more than a year before she started trusting people. Only with the help of watercolors was I able to capture her mysterious reserved, yet always attentive nature...

                                                                     

                                                                       Great Pyrenees

                                                                   Watercolor on paper

What kind of bird of prey or raptor is this?

A couple of months ago around 8:30 in the morning, I witnessed a raptor carrying away a small mammal out of our backyard, - which looked like a tree squirrel.

I was in awe, mesmerized by the confidence, calmness and grace of this magnificent bird and at the same time horrified by the sight of the limp small, rag-doll -like, mammal hanging in his claws…

After this unforgettable experience I ran into my studio and made this pastel composite sketch. Until now, nobody could help me identify this bird of prey. 

I'd appreciate the web community's help in identifying this raptor.

Thanks so much!