After significant early work on Middle Indo-Aryan dialects (Prakrits) she had specialised in Australian Aboriginal languages since 1963, when she took it up as a hobby.
On the assumption of power in Germany by Hitler, their position as Jewish people rapidly deteriorated, despite financial assistance from an uncle who had emigrated to the United States.
It was at that time that she began to pursue private studies in Aboriginal languages, managing to pull some from the brink of oblivion, as for example with Wangganguru, which she recorded with the assistance of her informant, Mick McLean Irinjili.
[8] After 1969, she took up an appointment as senior lecturer, and then reader, in Sanskrit, in the Department of South Asian and Buddhist Studies at the Australian National University, Canberra.
[12] In January 2016, AIATSIS presented Hercus with digital copies of the foundational sound recordings, of which she had made over 1,000 hours ranging over 56 native languages and dialects,[13] as a token of gratitude in celebrating her 90th birthday.