The Garden Bird Survey (GBS) is one of a number of continuing surveys conducted by Canberra Ornithologists Group (COG). This survey arose out of a realisation that COG has a large resource of members living in bird-rich environments that were made more interesting by a strong seasonal climatic variation. In establishing this survey COG believed that its members could contribute to a useful bird survey from their homes, with minimal cost and effort. This would provide individual members with an opportunity to contribute in a continuing way to the bird monitoring activities of the group. It would be interesting to monitor the seasonal and long-term changes in abundance of bird species in Canberra gardens.
The GBS was launched in 1981 and was officially announced by Neil Hermes in Canberra Bird Notes in June 1981. It has operated continuously since then.
Participants in the survey make a record, week by week, of the largest number of each species observed at any one time in their site. A site is defined as the area within a radius of 100 metres, approximately 3-hectares. The shape of the site is not necessarily a circle. All birds seen or heard within the area are recorded. Right from the beginning, the important point was made that common birds are more important than the occasional rare record.
The number of birds observed is entered on the Garden Bird Survey Chart. This is a large wall chart listing the most commonly occurring birds, with additional spaces for other species observed. There are 52 columns, one for each week, starting in the first week in July. The months on the chart are defined according to the GBS Calendar (see Glossary for exact definitions). At the end of the year, the completed charts are collected and the data entered into the Garden Bird Survey database, which is currently a Microsoft Access database. Observers record on the weeks which suit them, and any weeks which are not recorded are excluded from bird population data calculations. Overall, an average of 40 weeks per chart were recorded.
Over the 17-year period of the survey, 1101 charts were received from 270 sites. Fifty-seven charts were completed in the first year of the survey, and in subsequent years this number has varied. Eight observers returned a chart for each year of the survey.
In 1982, the COG Records Officer, McComas Taylor, stated that "the GBS is a new concept in Australian ornithology. This is the first time that a large number of people have been involved in an intensive urban observation program of this kind." In a very forward-looking message he wrote, "These systematic observations enable us to describe the bird population of Canberra more accurately than ever before. We can now measure the annual population fluctuations and describe geographical distribution of our local birds. |
In 2000 COG established population indices for many species, thus laying the foundation for measurement of long-term changes in our bird population. A wealth of areas awaits investigation: how does the age and composition of a garden affect its bird population? What role does proximity to bushland or permanent water play?"
From July 1981 to March 1987 McComas Taylor was responsible for the GBS, during which period the first effort was made to establish a computerised database for the GBS records. This led to advances in the statistical data in the ABR, and in 1986 breeding data from the GBS was included for the first time in the ABR. In April 1987 Grahame Elliott was listed as the GBS contact followed by Ian Baird in October 1990, and then Philip Veerman, who has been responsible for the survey until the present.
While the basic method and design of the GBS has remained constant since its inception, there have been significant developments in improving the Chart, and particularly in handling the data. In 1992 each site was given a unique identifying number. Philip Veerman implemented a database table in which each observer-site became one record. This major development allows the history of a site and the bird records from it to be followed. In 1995 Graeme Deaker developed a database in Microsoft Access.
This database enables linking of all the various facets and relating bird count, bird breeding and weeks used, to three parameters: GBS site, observation year and bird number (from the RAOU Atlas codes). Andrew Newbery compiled a set of routines to produce statistical output for the Annual Bird Reports from the data.
What exists today is a comprehensive and continuous set of data, the result of 17 years of systematic observation. The GBS data set is now a valuable information resource that awaits further analysis. The information published in this book is the outcome of a relatively simple analysis of abundance and distribution of bird species. The data set remains available for further research. |
