Mockingbirds (an American bird that imitates the calls of other kinds
of birds, in order to lay claim to a larger territory) are even
bolder.  Years ago, a pair of mockingbirds built their nest in a bush
next to my father's front porch.  Not only would they dive at anyone
who came near their nest, they would sometimes peck you on the way by.
Fortunately, they weren't large enough for the peck to do much damage.
On one occasion, I heard the mockingbird making a big fuss, and
discovered that my parents' cat was under a chair on the porch,
crouched as far to the back as she could manage.  The mockingbird was
striding back and forth on the porch (walking!), only a couple of feet
away from the cat.  The cat could easily have pounced on the bird, but
was intimidated by the bird's sheer bravado and noisiness.  I let the
cat into the house, and she didn't ask to go out again for several
hours.