Bird Identification: CLOSED: Large Bird - What is it?, 1 by tomkeelin

tomkeelin wrote:
Here in Menlo Park, California, we suddenly have several large birds that frequent the tip-tops of our (and our neighbors’) redwood trees each evening. We have no idea what they are and, in fact, have never seen birds like this frequent our neighborhood in three decades of living here.

In flight, they are white (or at least very light in color) when viewed from below – except only for some darkish highlights on the lagging edges of their wings. When sitting perched they seem to communicate with an unearthly low-pitched sound – like some combination of a screech and a guttural utterance.

Any idea what kind of birds they are? Thanks in advance for your help!