He said Zhou found the hedgehog in his garden on the evening of February 13 and believe it had earlier attacked chickens and that it would do it again.
"You stabbed the hedgehog with a steel rod and then, believing it to be dead, impaled it with the rod and left it in your back yard. Unfortunately the hedgehog wasn't dead."
Someone nearby heard the "screeching" of the hedgehog and called police, who found the animal still alive, with its innards "hanging out".
"The essence of the charge against you, of course, is that you caused the hedgehog unnecessary pain and suffering," Judge Davidson said.
"I have to say that I'm not at all confident that at a judge alone trial the prosecution would have necessarily been able to prove wilful ill treatment."
Zhou's lawyer said his actions were not "motivated by malice", but rather concern for his chickens.
"He accepts that he acted in haste and that his actions were frankly ill considered and inhumane," the lawyer said.
Zhou, who has no criminal history, felt "a great deal of shame and remorse" and has made a voluntary $200 donation to the SPCA.
The lawyer argued Zhou should not receive a conviction, because it could affect his ability to obtain future work as a subcontractor. He also said it could prevent Zhou from travelling overseas for his son's wedding when borders reopened.
Judge Davidson said Zhou appeared to be genuinely remorseful, had undergone a form of mentoring and counselling at his local church, and that the consequences of a conviction had the potential to be "quite significant".
He agreed to discharge Zhou without conviction.
It's not the first case of animal mistreatment to hit headlines this week.
An Auckland woman appeared in court this week after letting her dog become so emaciated that it could not stand on its own.
Bella the staffordshire bull terrier cross was found with discharge coming from her nostrils because of an untreated respiratory infection, and a vet found abnormal lung sounds and evidence that she had coughed up blood.
"She was too weak to stand on her own, and was covered in fleas," the SPCA said.
A second vet found Bella to be emaciated, moderately dehydrated and had tartar build-up on her teeth.
She also had a grade 4 heart murmur and excessively overgrown nails.
The dog had to be euthanised to avoid prolonging her suffering.
Her owner was sentenced to six months' supervision, disqualified from owning dogs for five years, and ordered to pay more than $1200 reparations to SPCA.
