The boy picked up a rock and threw it at the Kea - an endangered mountain parrot - killing it instantly.
The incident happened when around 200 children from a school in Christchurch, New Zealand were on a school outing.
Killing a Kea is a criminal offence that carries a maximum fine of £50,000 or six months in prison as they are protected by law under the Wildlife Act killing one.
There are thought to be fewer than 5000 of the birds left in the world.
Staff at Porter Heights Ski Area said they had been left 'upset' and 'disgusted' by the boy's actions.
The headteacher at the boy's school said he did not think there was any 'malice' in the student's attack.
Richard Paton said he thought the boys was 'as shocked as anybody' that the rock he threw 'actually hit the kea'.
"The boy involved is very remorseful, but there will be some consequences for his actions.
"The other students on the trip were as upset as anybody and they also feel let down by the mindless actions of one person.
"It's unfortunate that the actions of one person can reflect badly on the school," he added.
A silly and mindless moment of madness, or an inexcusable act of wickedness that should be severely punished?