Mr Scadden did a lot of work studying the breeding habits of the "widespread but somewhat endangered" birds, mapping their progress and maintaining and protecting their environment.
"He was a lovely and gentle, very caring, trustworthy man who was a terrific teacher," said Mr List.
For years Mr Scadden taught volunteers at Pukaha Mt Bruce Wildlife Centre.
Tenick Dennison said Mr Scadden's heavy involvement with Pukaha Mt Bruce "where he did an enormous amount of work" was one of his biggest contributions.
Dr Dennison said his longtime friend was keen on education and would teach people about birds, nature, and botany.
"He was a general naturalist, a person who was interested in all forms of nature."
Dr Dennison said Mr Scadden was a young pharmacist at Richards Pharmacy in Masterton, when they met 56 years ago.
"He was a very quiet achiever. What ever he did he did well and he did it without blowing his trumpet."
Dr Dennison said the well known Masterton bird watcher and long time community chemist was also a very good bird photographer.
Mr Scadden received The New Zealand Order of Merit for services to conservation in 2003.
He was also awarded a Meritorious Service Awards, "which is only given to a limited number of bird people in New Zealand, who have made significant effect on the state of bird life".
"He was one of Wairarapa's most distinguished conservationists. We have lost a very important figure in that field here in Wairarapa."
Mr Scadden wrote a lot about the birds of Wairarapa and where to find them and contributed to a chapter in the book Wairarapa Moana.
Dr Dennison said Mr Scadden was interested in Wairarapa history and pioneers, and used to record life stories of some older people in our area.
"He was a great friend and he did a lot for the area.
"We have lost one of our very eminent conservationists," said Dr Dennison.
A private funeral service will be held for Mr Scadden today.
