Document ID: chunk:federal_register_of_legislation:F2023L00138:front:0:p13
Version: federal_register_of_legislation:F2023L00138
Segment Type: other
Provision Reference: 
Character Range: 33789–36867

by River Red Gum (Eucalyptus camaldulensis) and subsequent loss of the open Moira Grass Plains from areas like the Barmah-Millewa Ramsar wetlands has the potential to reduce foraging opportunities for Australasian Bitterns. The coastal zone in Australia is still subject to intense and escalating pressure from housing, semi–rural and other developments and the swampy vegetation in some wetlands has declined as wetlands become deeper sumps for increased stormwater from paved and other hard surfaces in expanding urban areas (Jaensch 2004).

    Fire
   Intense and frequent bushfires or prescribed burning in wetlands reduces the density and cover of vegetation that forms the core habitat of the Australasian Bittern. Wetlands in southwest Australia have lost vegetation habitat due to summer fires when wetlands are dry (DBCA 2018). Many wetlands that support Australasian Bittern have deep peat beds. Severe fires can burn these peat beds and convert wetlands from shallow wetlands suitable for Australasian Bittern to deep wetlands with only minimal fringing vegetation which do not support Australasian Bittern. The combination of a period of dry phases followed by fire resulted in the loss of an estimated 60–70 per cent of the reed beds in the Macquarie Marshes Ramsar site, New South Wales (Oct-Nov 2019). While the Marshes would not have been providing habitat for Australasian Bitterns at the time, given that the wetlands were dry, this fire event is likely to have detrimental effect on the rigour and extent of the reed beds in this system.

   Individual wetlands may require different fire regimes depending on vegetation type and location. In Western Australia, without occasional fire, rush or sedge dominated wetlands may become too dense for the movement of Australasian Bittern (A. Clarke, pers. comm. cited in DBCA 2018). In Victoria, the Glenelg Hopkins Catchment Management Area are working closely with Traditional Owners and other landholders to conduct traditional burning across wetland areas of the Tyrendarra Indigenous Protected Area. Wetland areas are being burnt using traditional patch burning techniques to enhance habitat for the Australasian Bittern, encourage the regeneration of native plant species and support cultural practices.

    Livestock overgrazing
   The Australasian Bittern is sensitive to habitat damage as it has relatively specialised habitat requirements, preferring wetlands with dense vegetation. Livestock can trample nests, and through grazing damage the available foraging and shelter habitat, reducing access to food and exposing Australasian Bitterns to predators.

         2.2.3     Climate variability and change
   In Western Australia the majority of the range of the Australasian Bittern is within an area which has experienced reduced rainfall over the past few decades. The Western Australian Australasian Bittern Recovery Plan identifies climate change (i.e. changes in precipitation and evaporation rates) as one of the primary threatening process to Australasian Bittern populations (Pickering 2013,