Ferg Horne, 64, who has been farming since he left school at 15, said he had never seen anything quite like it.
He was trudging through pelting rain to rescue a neighbour's sheep from the floodwaters at their South Island farm near Dunedin on Saturday, when he spotted some dark shapes from a distance.
He was puzzled because he knew his neighbour, who in Russia attending a nephew's wedding, did not have any black-faced sheep.
Mr Horne got closer, he thought it might be debris from the storm, which had drenched the area, forcing the farmer to evacuate his home.
Then he saw the bedraggled rabbits hitching a ride - two on one sheep and a third on another.
"I couldn't believe it for a start," he said.
Nobody else would believe him either without proof, he thought, so he pulled out his phone to take a photo, an image he thought his grandchildren would enjoy.
But in fact, Mr Horne inadvertently shot a short video.
"It's a Samsung or a smartphone or whatever you call it. I swear at it every day," he said. "I'm absolutely useless with technology."
Mr Horne said the sheep were huddled together on a high spot on the farm, standing in about three inches of water.
He said the rabbits looked like they had got wet but seemed quite comfortable and relaxed atop their mounts.
Rabbits are considered a pest to farmers in New Zealand, and Mr Horne said when he sees one, he usually shoots it.
"But they'd showed so much initiative, I thought they deserved to live, those rabbits," he said.
Mr Horne herded the sheep to a patch of dry ground on the farm about 50 metres away, but the sheep did not like it.
"As they jumped through the water, the rabbits had a jolly good try at staying on," Mr Horne said.
He said the rabbits appeared to cling onto the wool with their paws. As they approached the higher ground, they fell off but managed to climb a hedge to safety.
Mr Horne sent his video to his son, who sent images to the local paper and posted them on Facebook.
"From then on it's just gone crazy," he said.