The Garden Bird Survey (GBS) has been run by the Canberra Ornithologists Group (COG) since 3 July 1981. Summary results of the GBS are published by COG in the Annual Bird Report published as an issue of "Canberra Bird Notes" in hard copy and on the COG website http://cbn.canberrabirds.org.au/
(navigate through the link to Canberra Bird Notes).
The basis of the Survey is a site equivalent in area to a circle of 100m in radius around the observer's home or workplace. Not all sites are circular but all are approximately 3Ha in area. There is no restriction on the elevation of the bird when observed, and birds flying over the site are included.
Most of the Survey sites are located in the urban area of the ACT but some are also located in the City of Queanbeyan and the villages and rural residential areas in the areas of NSW surrounding the ACT. A State indicator shows which sites are inside or outside the ACT.
The observation period is determined by standard starting dates for each year, with a year always commencing on 3 July. In most cases the observation period is 7 days so that within each year the starting date of each period is the same day of the week. Exceptions are:
- In Leap Years the period commencing February 26 is 8 days to accommodate the 29 February; and
- Every year the period beginning 25 June is 8 days to enable a seamless match to the first day of the week beginning 3 July.
The basic counting rule is to report the maximum number of birds of a species seen at any time during the week. For example:
- If ten birds of species "A" are seen on the first day of a period and twelve on the second day, record "12".
- If in the same period 4 birds of species "B" are seen on the second day and five birds of species "B" are seen on the sixth day report "5".
Application of this rule means that the survey results are not appropriate for measuring the numbers of birds that are migrating in flocks since only the biggest flock is recorded with no measure of the number of flocks.
It should be noted that number of sites operating in any period may vary, both between years and within a year. The number of sites tends to be low for the periods beginning 3 and 10 July (due to delays in obtaining new Charts) and from 18 December to 8 January due to observers being away on vacation.