I chased this Gray Catbird around behind our backyard for awhile without a camera trying to figure out what bird it was, then out came the neighbour's riding mower to end that pursuit. Only a short while later, as I was taking pictures of my rascals on the trampoline... who's sitting only 15m from me in our current bush - the same bird. I didn't know what it was till searching for a while on the internet, I finally figured it out: Gray Catbird.
If you look closely, you can see the rusty coloured under-tail.
It was being true to it's usual habits; its song was almost constant, and quite varied. The Gray Catbird is a relative to the mocking birds and thrashers. It also mimics songs of other birds in a varied mix of its own. You can distinguish it from mocking birds and others by its darker crown stripe, a rusty coloured under-tail section. It likes to forage off the ground, but likes to sing from the tops of bushes or trees. But it gets its name from it's pretty good imitation of a cat's meow, which apparently you can use to draw it out of denser brush where it will hide.