are the names of the two birds tether at the MCG to scare off the Silver Gulls. Yoko is a Peregrine Falcon and Zorro is a Wedge-tail Eagle.
There is a short video news item on the smh. site that has some good footage of the gulls on the pitch, in case you are like me and never watch AFL, and so don't have an idea of the issue. But even better The Doctor on Triple J has a short interview with Alice and Graham (the handlers) and the birds, on his radio program where Zorro interjects a few times. (its at 27:00- once the story has loaded you can move straight to that point)