
Among their plans, which included "heaps of adventures", Mr Tustin wanted to pick up on some of the projects that he loved but never had time for - like the moose. And the tahr.
Tustin, who lives at Bull Creek, is well known as New Zealand's moose man - he has spent years searching for the descendants of the North American moose released in Fiordland in 1910 - but lesser known is his involvement with Himalayan tahr.
That night, Tustin decided he wanted to write a book about tahr and dedicate it to the late Dr Graeme Caughley, a population ecologist, conservation biologist and researcher, who launched him on a lifetime pathway.
Not a textbook, just a chatty book - "telling how it was for them. And for me". And he did.
The Himalayan tahr was introduced into New Zealand a century ago for big-game sporting purposes.
From a few releases at Aoraki Mount Cook, tahr are now permanent inhabitants of the sub-alpine zones in the central Southern Alps.
Tustin's involvement with tahr began as a 19-year-old hunting them as scientific specimens for Dr Caughley.
It was extremely dangerous work, with risks posed by bluffs and river crossings, rockfalls and avalanches, but it was also a defining time for the young outdoorsman and a time of great camaraderie.
He went on to study tahr himself as a scientist for the Forest Research Institute, covering many aspects of their population demography, census, ecology, range use and behaviour; the latter involving a direct observation study, living alone in the Godley Valley in a tiny hut for the best part of two years.
That included spending three weeks in residence during a frosty stretch in June, 1976 when the temperature averaged -8degC. It was like being stuck in a household deep-freeze, unable to escape, he recalled.
He found an unlikely ally in a visiting possum, who accepted the hand of friendship - a jam sandwich - after making his presence known with a scratch on the roof.
While he did not normally care for possums, Tustin found it somehow comforting to know there was other life out there.
"There was a kind of cheering kinship, born from shared folly: We were the only two creatures dopey enough to live there."
Supported by some excellent photographs, New Zealand's Mountain Monarchs is not just another hunting book. It's a great yarn about one man and what has become a lifetime interest.
• Sally Rae is an ODT reporter.