"I hadn't heard the sound [of the kiwi] in so long because I was in Australia. Hearing the icon of New Zealand I was like 'oh mean' and then I heard the possum and thought 'oh that's right they're [kiwis] not doing so good.''
He went home and started looking at study options and decided on NorthTec's environmental management programme. At the end of the month Mr Sullivan will graduate with a Bachelor of Applied Science.
"I'd never considered conservation. For me outdoors meant farming or forklift driving."
Mr Sullivan is now a DoC ranger. He had heard a lot of volunteer work was required to work for DoC, so that's what he did.
"I did trapping, kiwi banding, weeding over on Hen and Chicks and the Poor Knights and kiwi monitoring in Whakatane and stuff on Waipoua," he said.
A couple of months ago, after volunteering in Dargaville, Mr Sullivan was offered his job with DoC. He took up a part-time position so he was able to continue with his studies.
He credits his wife, Tanja Sullivan, as being the driving force behind him completing his degree.
"Tanja really wanted me to do a job that I liked. None of it would have been possible without her."
Mr Sullivan said he has been doing a lot of iwi consultation for DoC and has worked on a privately-owned island off Matauri Bay which is being restored. He said he has also been learning te reo Maori, this ties in with his long-term aim of working to educate Maori in conservation.
"Learning about all these different birds and lizards you grew up hearing the myths and the stories about them. To see them in real life, it's not only diverse but quite fulfilling."
Mr Sullivan said he has an old school report card described as "shocking" which he uses to motivate himself, so he can prove he can do it.
