I had just arrived for my Sunday morning alone shift. I went into the night enclosure area to say good morning and Dar was sitting up on the floor in room 4. I approached to greet him signing, GOOD MORNING DAR. Dar responded by signing BRUSH. I found his favorite brush, knelt beside the caging, and signed GROOM. Dar pressed his back against the caging and agreed signing GROOM. After about five minutes Dar raised both his hands above his shoulder and signed FRIEND. He held his hand out to take the brush and I passed it to him. He placed the brush on the floor beside where he was sitting. Dar looked back towards me and signed CHASE softly. I ran away from him and he followed me with a series of somersaults.