He couldn't stop staring at the Slytherin Prefect. He knew it was rude but he just couldn't stop. He didn't want to miss it if the boy keeled over or something. Stare stare staaaaaare.

It was therefore rather ironic that his preoccupation with the Prefect, coupled with a poor vantage point, meant he missed the boy transforming into a bird altogether. Pity.