Barnes says her experience would have been extremely demanding as she would have tried to stay dry and light fires.
"You can last a long time without food so it's primarily if you have water and shelter you could last that long," he said. "Food issues are quite difficult in the New Zealand bush. It's been a mild summer but not dangerous temperatures."
However, the West Coast had endured "horrendous" weather during the six weeks Crooks was lost.
"It would have been extremely demanding just because lighting fires would have been very difficult unless you are very familiar with that environment."
The primary food sources on the West Coast were possums and eels. Vegetable supplies were extremely limited.
"Vegetable food supplies are very minimal in the New Zealand back country except in very specialist areas so basically it's protein - possums and eels."
He said a person could survive that long in the bush if they were able to conserve or use their energy wisely.
"Yeah, they would [survive] but survival means not being dead so basically if you're not using up more calories than you've got then you can keep ticking on. So if somebody sat quietly and meditated and preserved what they've got in terms of energy and warmth they would be okay.
"It's when they run around and expend more energy then they could go down quite quickly, so that's the crucial thing, in how you respond to the situation."
Crooks was found on a track near Punakaiki, 45km north of Greymouth.
Her rescuer gave the mum-of-four food and water before running for help, and Crooks was flown by the West Coast Rescue Helicopter to Greymouth Hospital.
The 36-year-old is recovering well, and spoke to police yesterday, Greymouth Sergeant Michel Bloom said.
"This is a remarkable story of survival. Ms Crooks set out to do a four-day walk in the Mt Bovis area when she became disorientated and sustained a leg injury.
"She was well equipped and has extensive bush craft knowledge, enabling her to survive for six weeks as she attempted to slowly make her way out of the bush."
Crooks was grateful for those who aided in her rescue, he said.
"She wants to express her gratitude to the tramper who found her, and everyone involved in the search and rescue efforts to try and locate her.
"Police would also like to thank everyone who helped us in our efforts to try and find her over the past six weeks. We are ecstatic this has had a positive outcome."
