Juvenile Cooper's hawks in the neighborhood. Usually there were two together making whistling sounds and going after squirrels who seem to be not very scared. Once in a while there were three, sometimes even four silhouettes in the tree.

The third picture shows the two hawks on a branch and a squirrel they just chased from the backyard. The squirrel hid under a truck, but after a while actually climbed onto a fence right near the birds and then climbed up the tree to look at them.
Also the goldfinches did not seem afraid as they usually are. One of the hawks flew right over the feeder and the goldfinches just kept eating.

The blue jays mobbed one of them and usually sit near them screeching.