That's a common grackle... I'm not sure I understand what the problem is? They do sometimes mob predators but I've never seen any ever mob a human-- they're usually pretty big sissies.They could be dangerous to any small fish, they're certainly known to feed on minnows as well as insects and invertebrates.

They absolutely love water for bathing. At the Chicago Botanic Gardens you'll see them in the rose garden fountain bathing all through the summer. They're probably waiting for you to leave so they can get access to the pond.

Ok, I am draining the pond so maybe that is why they are upset. I was looking for a nest because I have a bunch of small cedars and other types around it, but couldn't find anything. The one seems to follow me wherever I go and squawks, flies at my head at my constantly hovering about 5 feet over it. It is quite disconcerting

Hrm... That is mob behavior... I've had redwing blackbirds do to me while photographing nests. Never had a grackle do it, and I've been very close to grackle nests. RWBB's will actually try to take my head off if I didn't hold my arms and monopod in the air and look straight at them. If one's doing that behavior I don't blame you for being nervous!

They'll cavity nest and open nest in trees. Their nests tend to camo into the trees very well. So there's a good chance the one hovering you does have a nest near by. The good news there is that once the chicks fledge the bird should stop this behavior.

They are protected under the migratory bird act, so any deterrent method can't harm them. I've heard of people deterring RWBBs by spraying them with a jet of water from the hose-- though whether this is safe or humane is argued.

Just pick up your cleaning pace....... :)

Clever things. I would suggest a water cannon but the chickadees, sparrows and grackles set it off on purpose.

I don't think the water cannon would help, that's designed for birds that come around when you're NOT there. This bird is upset that she's there.

Gracks & other birds get aggressive & upset when they're tending fledglings. They may have some youngsters around, not in the nest anymore, that they are babysitting. A pond would be a good place for the kiddos to hang around.

And they do love water--like ducks. But they can't hurt you. They'll always be attracted to water but they'll be less easy to upset as the teenagers mature & move on.