When hiker Jessica Johnston fell from a 55-metre waterfall in wild New Zealand bush and was badly injured, her rescuers had to leave her missing dog behind.

This week, after strangers raised thousands of dollars for a search, border collie Molly was finally flown to safety by a helicopter pilot who was determined to reunite pet and owner.

She’d spent a week alone in the wild after an emergency rescue helicopter found Johnston with cuts and bruises after a fall at a rocky spot at the waterfall on the South Island.

Johnston was airlifted to hospital on March 24, while Molly remained behind.

The dog was bedraggled and hungry when she was found on Tuesday, just a few metres from the spot where Johnston had been lucky to survive.

Molly peers out of the door of a helicopter after her rescue. Photo: AAP

“I contacted her in hospital and said I’d go for a look for it,” said Matt Newton, the owner-operator of Precision Helicopters New Zealand, which is based at Hokitika Gorge near the Arahura River where Molly went missing.

“I went and looked for the dog several times and no avail.”

Unwilling to give up, Newton and his family launched a fundraiser to pay for more flying hours and advanced search gear.

Offers of help and donations poured in, with strangers pledging more than $NZ11,000 ($A9000) for a search.

It was enough to fund three more hours in a helicopter using thermal-imaging equipment.

On Tuesday, Newton took to the skies with a veterinary nurse, volunteer searchers and a dog named Bingo in a renewed search for Molly.

“We struck jackpot within about an hour,” he said.

Molly is reunited with her owner Jessica Johnston. Photo: AAP

Newton said there had been no sign of Molly at the waterfall when he previously searched the spot.

It wasn’t clear if the dog had also fallen from the waterfall or if she had eventually made her way to the spot where her injured owner landed.

The helicopter dropped low enough for a volunteer to disembark with the rescue dog Bingo to help coax Molly to safety and keep her calm.

Newton thought the dog had survived by eating feral animals during her week in the wilderness.

The dog was in “surprisingly good condition”, he said.

Wayne Holmes holds his dog Bingo, left, after the rescue of Molly, right. Photo: AAP

He sent word back to the helicopter base, where other volunteers waited to take turns in the search.

“Instead we just had a big barbecue and all had a cuddle with Molly,” Newton said.

Hours after the dog’s rescue, Johnston, still battered from her fall, arrived for a tearful reunion.

“I think that’ll speed up her healing process somewhat,” Newton said.

“Having your dog back, that’s for sure.”

-AAP