A Threatened Bird Index for South Australia
Date: 27, Nov, 2018
Publisher: TSR Hub
Here, the national Threatened Bird Index (TBX) is drilled down to report on information relating to trends for threatened birds in South Australia (Figure 1A). In its first iteration, this index incorporates data from 13 nationally listed bird species or subspecies (Vulnerable, Endangeredor Critically Endangered under the EPBC Act and/or as assessed by BirdLife Australia - see Table 1). More data will be added as they become available each year allowing the index to grow.
The index shows the estimated yearly change in relative abundance of threatened bird species in relation to a baseline year, for which 1985 was chosen, where the index is set to 1.0. However, later baseline years are also available to support the specific needs of conservation managers and can be selected via the web-app. Changes in the index are proportional—a value of 0.5 indicates the multi-species relative abundance is 50% below the baseline value; a value of 1.5 indicates 50% above baseline.
In 2015, the SA TBX value given the current data is 0.08. This suggests that the relative abundance of threatened birds for which we have data has decreased by 92% between 1985 and 2015. In comparison, the national TBX shows a decrease of 52% in the compiled data. Individual species in the South Australian index have values between 0.04 (a 96% decrease) and 0.17 (a 83% decrease). When a baseline of 2000 is used, SA TBX has decreased roughly 60% compared with 40% for the national TBX.