Zoo visitor's cruelty to rabbit
Llandudno Magistrates Court heard French took the rabbit from an area used for children to stroke animals.
The teenager had claimed a friend with him at the time was responsible.
The prosecution said French, accompanied by two other teenagers, took the rabbit from the petting area into a compound containing two alligators, where he dangled it from a balcony.
He dropped the rabbit and a male alligator named Albert took it in its jaws and killed it but did not eat it.
The court heard a young girl entered the alligator house and asked the three: "Is that a rabbit?"
The three are alleged to have fallen into fits of laughter as one answered: "It was - it was running around 10 minutes ago."
"He went into the other place, climbed on to a ledge and leaned over and he grabbed one of the rabbits by its ears.
"He said he was going to throw it to the alligators. I said 'Don't throw it in', but he did."
French said in court he felt guilty about the rabbit's death because he had been present at the time but was not responsible for it dying.
He blamed his 14-year-old friend, who cannot be named, saying the other boy had taken the rabbit from its pen and thrown it to the alligators.
He said: "We were all laughing about it. I was laughing just because of the shock of it happening.
"I felt as guilty as the others just for being there, but I didn't touch the rabbit."
However both his friends blamed him for the incident and suggested he was angry the rabbit had scratched his new jacket.
The court heard after leaving the alligator house, the boys also threw a lit cigarette to a chimpanzee, and French was seen reaching into an arctic fox enclosure.
French had previously admitted smashing two shop windows in Colwyn Bay in the early hours of the day after the rabbit killing.
Defence solicitor Chris Dawson had argued the court could not be sure who had thrown the rabbit.
Chair of magistrates Alan Roberts said: "Custody seems a very likely option."
French will be sentenced on 5 April.
Welsh Mountain Zoo administrative director Chris Jackson said after the trial he was pleased with the verdict."This is a salutary lesson to people who indulge in mindless attacks on defenceless animals," he added.