The endangered Eastern Bristlebird Dasyornis brachypterus is found in-a number of small isolated populations along the east coast of Australia. Presently little is known about the status and viability of many of these populations. Surveys for Eastern Bristlebirds were conducted at Red Rocks Nature Reserve, around Jervis Bay near Huskisson and on Beecroft Peninsula, and at Ku-ring-gai Chase National Park in south-eastern New South Wales to compare these data with historical records and to investigate more recent unconfirmed sightings of the species. Eastern Bristlebirds were resurveyed at Barren Grounds Nature Reserve, using the same sites as a previous long-term study from 1992 to 1998, to improve understanding of population density changes following fire. Among the sites of historical or unconfirmed records, ten Eastern Bristlebirds were found at Red Rocks Nature Reserve and four near Huskisson. None were found at either Beecroft Peninsula or Ku-ring-gai Chase National Park. At Barren Grounds Nature Reserve densities varied among sites of different post-fire age, ranging from 0.67 birds per 5 hectare in vegetation with the youngest fire-age of seven years to 1.6' birds per 5 hectare in vegetation with a fire-age of 19 years. For each site, the density was from 24 per cent to 60 per cent lower than in the 1992-98 study. We conclude that the consistency of these differences indicates differences in observer experience and training rather than a real decline in bird densities in these sites,' and suggest that this factor should be taken into account in interpreting the results of long-term bird studies that rely on data from different observers.