Document ID: chunk:federal_register_of_legislation:F2023L00138:front:0:p10
Version: federal_register_of_legislation:F2023L00138
Segment Type: other
Provision Reference: 
Character Range: 25475–28451

the activity (e.g. adjacent to the wetland vs activity in the catchment) and can be informed by expert opinion.

   When considering developments in any part of the Australasian Bittern's range, including in areas where the species 'may occur', surveys for occupancy at the appropriate times of the year remain an important tool in establishing the areas importance for the Australasian Bittern. In addition, consistent with natural fluctuations in availability of wetland habitat in Australia (whether an entire wetland or a temporarily inundated zone of a wetland), it is also important to note that the Australasian Bittern opportunistically use areas depending on the occurrence of suitable habitat and prey species so areas that may be important habitat over time might not have birds in any given year. This pattern of habitat use means that recent survey data and historical records and presence of suitable habitat need to be considered when assessing the relative importance of a site or region for the Australasian Bittern.

               Chapter 2
Threats

2.1            Historical causes of decline

             It is thought that the Australasian Bittern has been in decline for at least the past 30 years and declines since 2000 have been more pronounced (Garnett et al. 2011).
             The decline has been detected across both the eastern and western subpopulations and is associated with the loss of key breeding habitats (Garnett et al. 2011; DBCA 2018; Herring et al. 2019a).

2.2            Current threatening processes

             The main identified threats to the Australasian Bittern are the reduction in extent and quality of habitat due to the diversion of water away from wetlands (primarily for irrigation as well as groundwater extraction), the drainage of swamps, climate variability and change, the loss or alteration of wetland habitats due to urban and agricultural development, peat mining, predation by introduced animals such as foxes (Vulpes vulpes) and cats (Felis catus), reduced water quality as a result of increasing salinity, siltation and pollution, and overgrazing by livestock and detrimental fire regimes (Jaensch and Vervest 1988; Marchant and Higgins 1990; Kingsford and Thomas 1995; Garnett and Crowley 2000; Kingsford 2000; Jaensch 2004; Pickering 2013; DBCA 2018; Herring et al. 2019a).

2.2.1     Reduced wetland availability due to changed water regimes
             The major threat to the Australasian Bittern in Australia is the reduction in extent and quality of habitat, due to the diversion of water away from wetlands (primarily for irrigation as well as groundwater extraction), peat mining and the drainage of swamps (Marchant and Higgins 1990; Kingsford and Thomas 1995; Garnett and Crowley 2000; Kingsford 2000; Jaensch 2004; Garnett et al. 2011; DBCA 2018). Over the past 100 years, many suitable wetland sites in both eastern and south western Australia have been lost because of the alteration