A Threatened Bird Index for the Australian Capital Territory

Here, the national Threatened Bird Index (TBX) is drilled down to report on information relating to trends for threatened and Near Threatened birds in the Australian Capital Territory (Figure 1A). In its first iteration, this index incorporates data from two threatened (Vulnerable) and three Near Threatened bird species or subspecies (under the EPBC Act and/or as assessed by BirdLife Australia - see Table 1), which comprises a small proportion of ACT’s threatened and Near Threatened bird. The aim is to add more data as they become available every year allowing the index to grow. The index shows the estimated yearly change in relative abundance of threatened and Near Threatened bird species in relation to a baseline year, for which 2000 was chosen, where the index is set to 1.0. 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 ACT TBX value given the current data is 0.52. This suggests that the relative abundance of birds for which we have information has decreased by 48% between 2000 and 2015. While the overall index value in 2015 is 0.52, individual species have TBX values between 0.16 (a 84% decrease) and 1.95 (a 95% increase). The ACT value matches the national TBX which also shows a decrease of 52% in the compiled data between 1985 and 2015.