Some Conservation Issues

The graphs in this book tell an interesting story. They show how each species, as measured by the Garden Bird Survey, has fared in Canberra gardens over the past 27 years. Whether the numbers of an individual species are stable, increasing or decreasing, either by a little or a lot, raises many interesting conservation issues.

While the graphs cannot be interpreted as being an accurate representation of the bird populations of the ACT, they can be the starting point for discussion and, if necessary, further research.

Because data from the Garden Bird Survey are gathered in a systematic way, it is possible, for any survey year, to provide information on the distribution and relative abundance of birds using the gardens participating in the survey that year, and to compare from year to year. However, it is not possible to generalise the survey findings to the ACT as a whole, because “gardens” do not represent all the available habitats within the ACT.

In the first edition of Birds of Canberra Gardens, changes in distribution and abundance made it possible to rank the bird species. This enabled a table to be compiled, summarising changes to the more common species over the 17 years of the survey. This table has been revised to accommodate the 27 years of the survey, to the financial year 2007-08. Care must be taken when interpreting this table for it is assumed that any increase or decrease is due to a change in abundance and not to a change in behaviour.  Without being able to compare the Garden Bird Survey results with results from a survey of the region as a whole it is not possible to know if changes in behaviour have occurred.  For example, it is interesting to note the overall increase in Wedge-tailed Eagle sightings, although there is concern that numbers are not holding up in the Canberra region as a whole. This may well be caused by a change in behaviour and feeding range as rabbit populations became scarce due to the Rabbit Calicivirus Disease or other control measures. The fact may be that Wedge-tailed Eagles now range closer to, and sometimes over the suburbs, and thus turn up more regularly in garden bird surveys.

This chapter summarises the relative abundance of each species, and indicates which species are increasing, decreasing, or remaining stable. This summary provides an opportunity to address

several conservation issues. Because the dataset has limited capacity for generalisation to the ACT as a whole, care must be taken to ensure that this discussion does not jump to unsupported conclusions. Nevertheless, discussion of issues in a hypothetical or speculative way can raise interesting questions and be a valid contribution to discussion of ACT environmental issues.

Increasing Species
Stable Species
Decreasing Species
Destruction or modification of local habitat
Destruction or modification of distant habitat