The semi-retired electrician began his journey as a taxidermist when he was 19, living in Feilding.
"I got a beautiful skin and I tried to tan it but lots of hair fell off."
Mr McCosh had gone to (Arthur) Harold Fraser - a taxidermist who was often commissioned by recreational hunters in the 1950s and 1960s - asking where he had gone wrong.
Mr Fraser, who was "70-odd at the time", took the young Mr McCosh on as an apprentice, teaching him the trade.
"The only thing you are using from the animal is the skin, which is draped over a mould," said Mr McCosh.
His wildlife collection includes all the deer species found in New Zealand and the first wapiti to be shot under licence, after the skin was donated to Mr McCosh by the grandson of the hunter.
He has a warthog, a water buffalo, two alligators, a baby chimp, a sea turtle, owls, a kiwi, a penguin, a baby emu, an albatross and a hereford bull - amongst many others.
The Indonesian porcupine was stuffed "very carefully", said Mr McCosh, who also has more than 300 stuffed birds.
"Little birds are the hardest things because they're so fiddly and their skin is so thin.
"It's just like cigarette paper."
Mr McCosh and his wife Karen had the animals displayed in their lounge room many years ago.
When they started doing guided canoe tours along the Ruamahanga River the couple would invite the guests back to their place for tea and coffee.
"They'd come back and look in the lounge and we could see that [the animals] were an attraction."
Mr and Mrs McCosh bought a house beside the river, built the log cabin in 1984 to display the animals, and offered a "total outdoor experience" with canoeing and a gallery visit.
"Back then you just went out and did it without consents so I did that and it really went crazy.
"On the weekends we were doing 40-odd people a day."
Mr McCosh adopted the nickname "Tuatara Ted" which was given to him by visiting high school students, who said he was New Zealand's version of Crocodile Dundee.
"They said Tuatara John doesn't sound right so Tuatara Ted it is."
He had been wearing his Akubra hat, as he always did, while taking Marsden Collegiate girls out on the canoes.
Tuatara Ted stuck and, back in his heyday, he starred in three television shows under the pseudonym.
Mr McCosh said taxidermy was about preserving an animal in a life-like stance and educating children about the animals of the world.
"A little boy came here and asked his father if he could see the animals.
"I could tell he was blind. He ran his hand over a bird and said daddy, the bird is flying.
"And that's what taxidermy is all about - where people can appreciate the animal."
Mr McCosh, who was the taxidermist for Wellington Zoo "off and on over the years", has just one rule - he refuses to stuff people's pets.
"I don't do pets because I can't put the soul back into the animal."
Mr McCosh is one of 16 taxidermists in New Zealand.
He has two daughters, two sons and 16 grandchildren, and enjoys spending his time fishing and whitebaiting.
These days, instead of guided tours in canoes, "freedom paddling" is on offer and a donation box is at the entrance to the taxidermy gallery.
