Historically, helmeted honeyeaters were patchily distributed in the mid-Yarra and Western Port catchments of central southern Victoria, in the South Eastern Highlands IBRA bioregion. Their range and population declined steadily through the 20th century, with the population reaching a low of 15 breeding pairs and about 50 individuals in late 1989, the year a recovery program began. Former colonies at Cockatoo and Upper Beaconsfield had become extinct not long before as a consequence of the Ash Wednesday bushfires of February 1983. Following the implementation of the recovery program the population increased to a peak of about 120 individuals in 1996, but has since declined to about 20 wild breeding pairs.