Interesting article (and great photo gallery) at National Geographic about scientists breeding rats and foxes for violence and domesticity. (That's a angry rat, above.)
According to the video, there's a goose in Echo Park (in Los Angeles) that inexplicably fell in love with an older man who visits the park regularly. Not only does the goose wait for the man to arrive, and follow him around at the park, but it also tries to follow him home each day.