Indigenous Australians in contact with the colonists were enumerated at many of the colonial censuses.

When the Australian Federation was formed in 1901, the new Constitution contained a provision (Section 127), which said: "In reckoning the numbers of the people of the Commonwealth, or of a State or other part of the Commonwealth, aboriginal natives shall not be counted."

In 1967, a referendum was held which approved two amendments to the Australian constitution relating to Indigenous Australians. The second of the two amendments deleted Section 127 from the Constitution.

The Commonwealth Bureau of Census and Statistics interpreted of the of Section 127 was that "aboriginal natives" were to be excluded from published tabulations of population. Aboriginal people living in settled areas were counted to a greater or lesser extent in all censuses before 1967.

The first Commonwealth Statistician, George Handley Knibbs, obtained a legal opinion that "persons of the half blood" or less are not "aboriginal natives" for the purposes of the Constitution. At the first Australian census in 1911 only those "aboriginal natives" living near white settlements were enumerated, and the main population tables included only those of half or less Aboriginal descent. Details of "half-caste" (but not "full-blood") Aborigines were included in the tables on Race. Details of those "full-blood" Aborigines enumerated were included in separate tables.[10] This practice was followed in all subsequent censuses up to 1966.

http://en.wikipedia.org/wiki/Census_in_Australia