Sakarai has passed along another picture of the day and the following message.
Pic of the day. Never bully Cuccos. Seriously, attacking them is out of the question! This has always been a cardinal rule of The Legend of Zelda series.
What does this mean? Well my only assumption is that the Cucco is a possible Assist Trophy or even a new hazard item further then that I do not know perhaps it could be an attack of Toon Link. Given that the background is the Animal Crossing stage and not a Zelda one my guesses seem likely but more then likely this is referencing a major chicken strike.