After gaining a PhD in Zoology from the University of Montana, Charles moved to New Zealand in 1982 to take up a lectureship in evolutionary ecology and genetics at Victoria University of Wellington. During his time at Victoria he served as Head of Biological Sciences, Professor of Ecology and Assistant Vice-Chancellor.

Charles has worked closely with the Wildlife Service, Department of Conservation, and WWF New Zealand, to help secure the future of tuatara, kiwi and other natural treasures.

In 1999 he was elected a Fellow of the Royal Society of New Zealand, and in 2005 he was made an Officer of the New Zealand Order of Merit (ONZM) for Services to Conservation and Biology. He is the Chair of the Hawkes Bay Biodiversity Foundation, a Trustee of Predator Free New Zealand Trust (PFNZT) and former Trustee for Zealandia Sanctuary.

Charles retired in 2016, and is now based in the Hawkes Bay. He is enjoying the opportunity to continue his long association with conservation through his work with ZIP.