Martin Butterfield, who gathers statistics and breeding data for the survey said: ''They are probably just about the most promiscuous bird we've got, we also collect details of breeding which starts off with courtship display and they are at it like vipers the whole year long.''

Their abundance soared 245 per cent in the 2009-10 survey compared with their long-term average over the past 30 years.

He said only one or two crested pigeons were recorded in north-west Belconnen in the early 1980s.

''In some early years hardly anyone reported them, then they spread. Over the last few years probably every site has reported them and now they're a very common bird.''

The crested pigeon's rise is tiny compared with the little corella, whose sightings have exploded by more than 1000 per cent. Galahs are the most abundant in the survey.

Survey volunteers choose an area equivalent to a circle with a radius of 100 metres around their home and report the maximum number of birds at any one time.

Mr Butterfield said the methodology was little changed since the first survey in 1981-82 when 56 sites were observed, for a total of 2021 weeks of observation.

Mr Butterfield's bird interest began in his childhood in England, banding them for a hobby. Retired from the Australian Bureau of Statistics, his expertise in data collection is put to good use in COG. The number of survey volunteers built solidly as they gathered information for a bird atlas in the mid-1980s, after which numbers dwindled to 43 volunteers in the mid-1990s. Now they're in the high 70s and 80s.

Data is sent to members for analysis. Each species is written up and totalled 169 in the last survey, four more from the previous one, ranging from 972 records of galahs to the red-capped robin, often seen on fences and ranked 165th in the latest survey. John Thistleton