This raptor and I studied each other near my home in Portola Valley Ranch. A large bird, it did not look like the usual Red-tailed Hawk to me. I wondered: Golden Eagle?
Many people responded, with various ideas. My current judgement has settled on juvenile Red-tailed Hawk, dark morph. See below for a selection of the many helpful comments that led me to this conclusion.
If you have walked down Mader Valley, or along Valley Oak at its lower end, or Black Oak Trail beyond Valley Oak, you might have heard the sharp, insistent call of the Red-tailed Hawk (Buteo jamaicensis). Dudley Carlson and many others feel this photo shows one of the two Red-tailed Hawks that have been often seen and heard in this area. (When I took this photo, I did not hear the call. But I have heard the hawks calling, many mornings.)
For your interest, I have collected a few of my photos of local Golden and Bald Eagles -- and other related birds -- at the bottom of the "Portola Valley" group: <
capturethelight.zenfolio.com/eagles>.
Here are a few of the many comments relevant to identifying this bird. (It is difficult to ID a bird from a few photos only, one perspective, no behavior or call.)
Lisa Wan: "It is unlikely a Golden/Brown Eagle since its legs are bare. Golden's have feathers right down to their feet...
It's a beautiful bird and will help lower the squirrel population (temporarily) that everyone seems so annoyed about!
"Make sure NO ONE is using rat poison or bait or that will be the end of this guy-Pass that message on!!" Dudley Carlson: "For all those fans of eagles, I'm hoping Dan will be able to get confirmation or counter-information from someone at Jasper Ridge on these photos. Carol Grundfest and I have been watching one of these birds on Longspur, in Mader Valley, and in the "bowl" below the Mader Valley side of Coalmine View for a couple of weeks (there are now two of them, seen together). My very strong feeling, though I'm no expert, is that these are juvenile dark-morph Red-tailed hawks. They do look very large, but that's typical of first-summer birds. If you look closely at Dan's photos, you'll see that the tail (not the wings, which cover the tail) has multiple dark and light stripes; a young Golden Eagle would have a broad white band inside a dark band. If you look on
allaboutbirds.org (Cornell) and listen to the call of juvenile red-tails, it's a perfect match for the high-pitched, shrill, repetitive sound these birds make, quite different from the much slower adult red-tail's call or from the hoarser eagles' calls. The red-tail's wingspan is 46-58 inches (nearly 5'); Golden and Bald Eagle are both 72-96 inches. On this bird, the tail in flight doesn't show any red; it's too young, and it's very dark. Red-tails show one of the most diverse ranges of coloration - two full pages in some guides.
"Golden eagles HAVE been seen in PV and nearby. They're known to nest at Crystal Springs, and they've been seen at the Dish and in PV proper. I don't think this is one of them. My two cents."
Valerie Baldwin: "Hard to tell without seeing the beak and size but it looks like the juv red tailed hawk I released Wednesday from the top of Windy Hill. She was big and flew off in that direction."
Female makes sense. Larger than the males. Competent, confident.
Several other comments noted the size and apparent aggressiveness (lack of fear?) of this bird -- watch out for your pets! Mike Housman: "Hmm, he's looking at you like you are lunch!"