Biodiversity

Species Profile and Threats Database


For information to assist proponents in referral, environmental assessments and compliance issues, refer to the Policy Statements and Guidelines (where available), the Conservation Advice (where available) or the Listing Advice (where available).
 
In addition, proponents and land managers should refer to the Recovery Plan (where available) or the Conservation Advice (where available) for recovery, mitigation and conservation information.

EPBC Act Listing Status Listed as Endangered
Listing and Conservation Advices Commonwealth Listing Advice on Botaurus poiciloptilus (Australasian Bittern) (Threatened Species Scientific Committee (TSSC), 2011v) [Listing Advice].
 
Commonwealth Conservation Advice on Botaurus poiciloptilus (Australasian Bittern) (Threatened Species Scientific Committee (TSSC), 2011w) [Conservation Advice].
 
Recovery Plan Decision Recovery Plan required, it occurs across multiple state boundaries and requires a complex suite of recovery and threat abatement actions in terms of addressing threats, such as water management in the Murray-Darling Basin. In addition, the implementation of recovery and threat abatement actions will involve a wide variety of land managers and other stakeholders across these state boundaries (02/02/2011).
 
Adopted/Made Recovery Plans
Federal Register of
    Legislative Instruments
Amendment to the list of threatened species under section 178 of the Environment Protection and Biodiversity Conservation Act 1999 (112)(02/02/2011) (Commonwealth of Australia, 2011m) [Legislative Instrument].
 
State Government
    Documents and Websites
NSW:New South Wales Murray Biodiversity Management Plan (Murray Catchment Management Authority (Murray CMA), 2012) [State Action Plan].
NSW:Review of the Threatened Species Conservation Act Schedules 2007-2009 (NSW Scientific Committee (NSW SC), 2009b) [State Species Management Plan].
State Listing Status
NSW: Listed as Endangered (Threatened Species Conservation Act 1995 (New South Wales): December 2013 list)
SA: Listed as Vulnerable (National Parks and Wildlife Act 1972 (South Australia): June 2011 list)
VIC: Listed as Threatened (Flora and Fauna Guarantee Act 1988 (Victoria): February 2014 list)
WA: Listed as Endangered (Wildlife Conservation Act 1950 (Western Australia): September 2013 list)
Non-statutory Listing Status
IUCN: Listed as Endangered (Global Status: IUCN Red List of Threatened Species: 2013.1 list)
VIC: Listed as Endangered (Advisory List of Threatened Vertebrate Fauna in Victoria: 2013 list)
NGO: Listed as Endangered (The Action Plan for Australian Birds 2010)
Scientific name Botaurus poiciloptilus [1001]
Family Ardeidae:Ardeiformes:Aves:Chordata:Animalia
Species author (Wagler, 1827)
Infraspecies author  
Reference  
Distribution map Species Distribution Map

This is an indicative distribution map of the present distribution of the species based on best available knowledge. See map caveat for more information.

Illustrations Google Images

The Australasian Bittern is a large, stocky, thick-necked heron-like bird with camouflage-like plumage. Individuals grow to a length of 66–76 cm, with a wingspan of 1050–1180 cm. Males weigh up to 1400 g and females weigh up to 900 g (Marchant & Higgins 1990).

The upperparts of the body are brown, dark brown to black and mottled buff in complex patterns that aid the bird's concealment in swamp vegetation. The underparts of the body are streaked and scalloped brown and buff. The bird has a prominent black-brown stripe running down the side of the neck, the eyebrow is pale, and the chin and upper throat are white. The species’ bill is straight and pointed, straw yellow to buff in colour, with a dark grey culmen (dorsal ridge of the bill). The legs and feet are pale green to olive; and the iris orange-brown or yellow (Jaensch 2005 pers. comm.; Marchant & Higgins 1990; Pizzey & Knight 1997).

Dark and pale variants of the plumage have been observed in adults, but the variations are not well understood. The sexes are similar in appearance, but females are smaller (Marchant & Higgins 1990). Juveniles are generally paler than adults (Marchant & Higgins 1990; Pizzey & Knight 1997), with heavier buff flecking on the back; adults and juveniles are probably not separable in the field (Marchant & Higgins 1990).

The Australasian Bittern is generally solitary, but sometimes occurs in pairs or dispersed aggregations of up to 12 birds. The species apparently breeds in solitary, territorial pairs but little more is known about its breeding ecology. It is probably sedentary in permanent habitats, but some individuals possibly make regular short-distance movements during winter, and occasional movements to inland areas have been recorded during extensive flooding (Marchant & Higgins 1990; Jaensch 2005 pers. comm.).

The Australasian Bittern occurs from south-east Queensland to south-east South Australia, Tasmania and the south-west of Western Australia (Marchant & Higgins 1990).

In Queensland, the Australasian Bittern occurs in the far south-east; it has been reported north to Baralaba and west to Wyandra, although in most years it is probably confined to a few coastal swamps (Marchant & Higgins 1990; Jaensch 2005 pers. comm.). Today, it is rarely recorded in Queensland, and possibly survives only in protected areas such as the Cooloola and Fraser regions (Jaensch 2005 pers. comm.).

In NSW, this species occurs along the coast and is frequently recorded in the Murray-Darling Basin, notably in floodplain wetlands of the Murrumbidgee, Lachlan, Macquarie and Gwydir Rivers (Jaensch 2005 pers. comm.; Marchant & Higgins 1990; NPWS 1999). Aggregations of Australasian Bittern consistently occur at wetlands such as Fivebough Swamp (at Leeton, NSW), where habitat is actively managed for this species and is supplemented by nearby ricefield habitat (FTWMTI 2002).

In Victoria, it is recorded mostly in the southern coastal areas and in the Murray River region of central-northern Victoria (Jaensch 2005 pers. comm.).

In Tasmania, the Australasian Bittern was formerly widespread, and was most numerous in the east of the state (Marchant & Higgins 1990). It is potentially absent from some major wetlands that have dried out (Garnett & Crowley 2000) and more recent records suggest that it is now confined to coastal regions in the north-east (Jaensch 2005 pers. comm.). This species also occurs on islands in Bass Strait (Marchant & Higgins 1990).

In South Australia, the Australasian Bittern is confined to the south-east, ranging north to the Murray River corridor and west to the far southern Eyre Peninsula and Kangaroo Island. It is most numerous in the swamps in the south-east of the State, notably Bool Lagoon (Jaensch 2005 pers. comm; Marchant & Higgins 1990).

In Western Australia, the Australasian Bittern was formerly widespread in the south-west, ranging north to Moora, east to near Mount Arid, and inland possibly as far as the Toolibin Lake area, but this range declined throughout the 20th century. Now it probably occurs only on the western coastal plain between Lancelin and Busselton, in the southern coastal region from Augusta to east of Albany and inland to some wetlands in the jarrah forest belt, with small, isolated populations in swamps from west of Esperance eastwards to near Cape Arid (Jaensch 2005 pers. comm; Marchant & Higgins 1990). The largest concentration is said to occur in the Lake Muir wetlands complex (Jaensch & Vervest 1988a; Jaensch et al. 1988).

Vagrants have been recorded from farther north, including one record from Argyle Downs in the extreme north-east of Western Australia (Marchant & Higgins 1990).

Extent of occurrence

The extent of occurrence of the Australasian Bittern is stable, at an estimated 1 270 000 km² (Garnett et al. 2011). This estimate is considered to be of high reliability. The contraction of the species’ range at the limits of its distribution (i.e. in south-east Queensland, Tasmania and the south-west of Western Australia) in the past century indicates that the extent of occurrence has declined during the 20th century.

During years of extensive flooding, the bittern can irrupt into floodplain wetlands (Jaensch 2005, pers. comm.) which, if breeding is successful, may result in a short to medium term increase in numbers. However, floods of such magnitude are rare and may only occur a few times each century. Such irruptions are unlikely to impact upon the extent of occurrence (Jaensch 2005, pers. comm.).

Area of occupancy

The estimated area of occupancy is 2580 km², an estimate considered to be of high reliability (Garnett et al. 2011). There is a declining trend present in the area of occupancy (Garnett et al. 2011). In the past century, many suitable wetland sites in both eastern and south-west Australia have been lost or have had their habitat altered.

The Australasian Bittern is also known to occur in New Zealand and New Caledonia, including Ouvea in the Loyalty Islands (Marchant & Higgins 1990; TSSC 2011v). An estimated 26 to 50% of the total global population resides in Australia (Garnett et al. 2011).

The global population size of the Australasian Bittern was estimated in 2002 to be 2500-3000 birds. However, this figure was based on an estimate of 2500 birds in Australia and up to 50 birds in New Caledonia (Delany & Scott 2002). The current population estimate for Australia is <1000 mature individuals and the species is now likely to be locally extinct in New Caledonia (Garnett et al. 2011). If the New Zealand population is assumed to be stable, the current global population estimate is therefore 1450 to 2950 individuals, <1000 of which occur in Australia.

Garnett and colleagues (2011) identify two ‘subpopulations’ of the Australasian Bittern, one in the south-west of Australia (Western Australia) and one in the south-east of Australia (Queensland, NSW, Victoria, South Australia and Tasmania). A previous estimate of three subpopulations (Garnett & Crowley 2000) was presumably derived by dividing the south-east Australian population into two separate subpopulations (one on the mainland and one in Tasmania) and is likely to be incorrect, given that many waterbirds are known to travel across Bass Strait (Jaensch 2005, pers. comm.). Their relatively sedentary nature and lack of large-scale movements or migration indicates that the two sub-populations are not likely to interbreed (Birds Australia 2005 pers. comm.; Marchant & Higgins 1990).

In south-west Australia (Western Australia), the Australasian Bittern is confined to a relatively small number of regularly occupied locations. These locations probably number less than 70, including: less than five north of Perth; less than 10 in the greater Perth metropolitan area; less than 10 south to Busselton; less than 10 in the Lake Muir district; less than 10 from Augusta to Walpole; less than 10 around Albany; and less than 10 around Esperance and Cape Arid. Most of these sites are discrete basin/sumpland wetlands with local catchments, and many depend on the surface expression of groundwater. Some sites in the Augusta-Walpole and Lake Muir districts are more extensive, and are members of wetland networks (Jaensch 2005 pers. comm.). The number of adult birds estimated to be present in this sub-population is 38-154 (Garnett et al. 2011).

In south-eastern Australia, the Australasian Bittern occurs in discrete wetlands or wetland clusters in some parts of its range, most notably in the south-east of South Australia and into western Victoria, and in coastal areas in general. In the inland regions, the species inhabits vast floodplain wetland systems; although today these are effectively reduced to small areas of remnant habitat, except in exceptionally wet years (Jaensch 2005 pers. comm.). Targeted surveys in 2012-13, observed the likely presence of several hundred bitterns using rice crops and, if breeding, such food production wetlands may be globally significant for the species (Herring & Silcocks 2014). The number of adult birds estimated to be present in this sub-population is 209-642 (Garnett et al. 2011).

It has been noted that some subpopulations may be larger than previously thought, given the relative scarcity of targeted survey work, the cryptic nature of the species, the large size of some suitable swamps and the possibility that the species could occur in small swamps that were not included in calculations of population estimates (BirdLife International 2000a; Heather & Robertson 1997). However, this is offset by the probability that much of the species' inland habitat in the Murray-Darling Basin and south-western Australia is often unsuitable due to drought, salinisation and reductions in floodplain inundation (Jaensch 2005 pers. comm.).

In regards to the density of populations and home range size, wetlands of varying size (from 5-300 ha) have been known to contain only one calling bird. However, at Lake Pleasant View, Western Australia, five calling birds were identified in 200 ha and at Lake Kulunilup, Western Australia, four were heard calling in 200 ha. Therefore, home ranges or territories appear to be equivalent to one pair every 40-50 ha (Marchant & Higgins 1990). Bitterns are rarely found in wetlands that contain only small patches, or a narrow fringe, of cover. It is therefore likely that birds may require large territories with substantial cover in order to breed (Jaensch 2005 pers. comm.).

Many Australasian Bittern sites are located in protected areas (Jaensch 2004), including Fivebough Swamp (Ramsar) (NSW), Bool Lagoon Game Reserve (South Australia) and Lake Muir Nature Reserve (Western Australia); all of which are managed to benefit the resident Australasian Bittern individuals (Garnett & Crowley 2000; Jaensch 2005 pers. comm.).

In south-west Western Australia, it is suggested that probably 50% of known Australasian Bittern sites occur wholly or partly within reserves. Reserves in south-west Western Australia that contain more substantial populations and/or extensive areas of suitable habitat include Benger Swamp, Gingilup Swamps, Owingup Swamp, Two Peoples Bay, Lake Muir (Byenup Lagoon, Tordit-Garrup Lagoon), Kulunilup Swamp and Lake Pleasant View Nature Reserves, and D'Entrecasteau (Lake Jasper area) and Cape Le Grand National Parks (Jaensch 2005 pers. comm.).

In south-east Australia, prominent areas of reserved Australasian Bittern habitat include Macquarie Marshes Nature Reserve and Fivebough Swamp (Ramsar) in NSW, Barmah Forest (Ramsar) and Kerang Wetlands (Ramsar) in Victoria, and Bool Lagoon Game Reserve in South Australia. The exact proportion of the south-eastern Australian population that occurs within reserves is unknown, but it is thought to be significant (Jaensch 2005 pers. comm.).

The Australasian Bittern occurs in terrestrial freshwater wetlands and, rarely, estuarine habitats. It favours wetlands with tall, dense vegetation, where it forages in still, shallow water up to 0.3 m deep, often at the edges of pools or waterways, or from platforms or mats of vegetation over deep water. The species favours permanent and seasonal freshwater habitats, particularly those dominated by sedges, rushes and/or reeds (e.g. Phragmites, Cyperus, Eleocharis, Juncus, Typha, Baumea, Bolboschoenus) or cutting grass (Gahnia) growing over muddy or peaty substrate (Marchant & Higgins 1990).

In the south-west of Western Australia, the Australasian Bittern is found in beds of tall rush mixed with, or near, short fine sedge or open pools. The species also occurs around swamps, lakes, pools, rivers and channels fringed with lignum (Muehlenbeckia sp.), canegrass (Eragrostis sp.) or other dense vegetation (Marchant & Higgins 1990) and may be found in ricefields and swamps sustained by irrigation (Jaensch 2004; Marchant & Higgins 1990). The species occasionally ventures into areas of open water or onto banks. Temporary pools may be visited when population density is high, or during short or large-scale bird movements. Brackish water is tolerated in estuaries and tidal wetlands, where birds inhabit beds of rushes or reeds in saltmarsh, especially near mouths of creeks or freshwater seepage; sea coasts are avoided (Marchant & Higgins 1990).

Knowledge of the breeding ecology of the Australasian Bittern is relatively poor. Available data indicate that the Australasian Bittern breeds in relatively deep, densely vegetated freshwater swamps and pools, building its nests in deep cover over shallow water (Marchant & Higgins 1990). In rushland, it may avoid breeding in the densest areas (Marchant & Higgins 1990); alternatively, this may simply reflect the accessibility of the few nests that have been found (Jaensch 2005 pers. comm.). If population density is high, it may resort to open wetlands for nesting, e.g. in stunted Acacia swamps (Marchant & Higgins 1990), but this may be exceptional behaviour (Jaensch 2005 pers. comm.).

It is clear that a complexity of habitat is required in order for foraging and breeding to occur in one location. The species requires shallow water, less than 30 cm deep with medium to low density reeds, grasses or shrubs for foraging and needs deeper water, with medium to high density reeds, rushes or sedges for nesting (Pickering 2013).

The Australasian Bittern occurs with the Australian Painted Snipe (Rostratula australis) (which is also listed as Endangered under the Environment Protection and Biodiversity Conservation Act 1999; EPBC Act) in floodplain and basin wetlands of the Murray-Darling Basin and in south-eastern South Australia (FTWMTI 2002; Jaensch 2005 pers. comm.). It may also associate with several wetland bird species listed as migratory under the EPBC Act, including Latham's Snipe (Gallinago hardwickii) and Wood Sandpiper (Tringa glareola) (Birds Australia 2005 pers. comm.).

Little information is available on the reproductive biology of the Australasian Bittern. It breeds in single solitary pairs, but sometimes several nests may be placed quite close together.

Breeding has been recorded from October to February; however, the Australasian Bittern is likely to breed when the plains are inundated by floodwaters, the timing of which can vary considerably (Jaensch 2005 pers. comm.). The species nests in swamps, generally in stands of Phragmites sp., Typha sp. or rushes (e.g. Juncus, Baumea) up to 2.5 m tall. Nests are usually placed about 30 cm above water level, but the water level can fall during the breeding season and leave the nest higher still. During one breeding season in the Riverina, NSW, nests were built in Boree (Acacia tephrina) trees amongst short (0.3 m) vegetation, a situation described as unusually conspicuous (Marchant & Higgins 1990).

The nest is a well-constructed saucer of flat pieces of reeds or rushes that are laid across one another; it measures about 35-40 cm across and 20-22 cm thick, and may be sheltered above by stems of the surrounding vegetation. The eggs are oval, smooth and glossy, and pure olive in colour; they measure 49-54 mm (Marchant & Higgins 1990). Clutch-size is usually four or five, but can range from three to six (Marchant & Higgins 1990; Serventy & Whittell 1976).

In New Zealand, eggs are laid from September to November. Clutch-size is usually four, but ranges from three to five. In New Zealand it has been noted that eggs are incubated by the female for a period of approximately 25 days and the female alone feeds the nestlings, which fledge at about seven weeks (Heather & Robertson 1997).

The Australasian Bittern has been recorded feeding on freshwater crayfish, fish (including goldfish), beetles, snakes, leaves and fruit (Marchant & Higgins 1990), as well as frogs and tadpoles (Jaensch 2005 pers. comm.). In New Zealand, it has been known to feed on spiders, insects (including crickets), crustaceans (including freshwater crayfish), fish (including eels), frogs, lizards, birds (including Silvereyes, Zosterops lateralis), rats and mice (Heather & Robertson 1997; Marchant & Higgins 1990). A recent study observed an Australasian Bittern eating Growling Grass Frogs (Litoria raniformis), listed as Vulnerable under the EPBC Act, at a rate of one every 21 minutes, with a total of 17 frogs taken in one feeding event (Menkhorst 2012).

When hunting, the Australasian Bittern holds its head and neck parallel to the surface and sways its head from side to side, or keeps absolutely still for 10 minutes, before lunging at prey by pivoting on the legs and keeping its neck and back straight. They will also lunge from a crouched position, sometimes lifting the feet from the surface to do so (Marchant & Higgins 1990). Hunting of frogs beneath dense vegetation has also been observed (Menkhorst 2012). Prey is either swallowed whole, the bird lifting its head skywards to do so, or prey is shaken and battered until subdued. They have also been recorded baiting fish with small pieces of grass (Marchant & Higgins 1990). Dunking of frogs has been observed, possibly to wash mucus from the skin (Menkhorst 2012). Most foraging appears to take place during dawn and dusk, though they have been recorded feeding during the day (Marchant & Higgins 1990; Menkhorst 2012).

The Australasian Bittern is considered to be sedentary in permanent habitats, but possibly makes regular short-distance movements during winter and occasional migrations to ephemeral habitats during wetter years. In Victoria, reporting rates suggest that no regular seasonal movements occur, however they may undergo local migration, with numbers on lakes near Geelong increasing during winter. Similar winter influxes have also been recorded at Lake George in NSW. No seasonal movements have been recorded at Bool Lagoon, South Australia, or in south-west Australia, though they are more likely to be recorded away from their usual distribution in the non-breeding season.

The Australasian Bittern formerly appeared to be resident in swamps in south-west NSW (Marchant & Higgins). More recent data from NSW indicates that the Australasian Bittern moves into the Macquarie Marshes and Gwydir wetlands during periods of inundation, which may be only three to six months, or not at all in some years; and that the species is absent from Fivebough Swamp for several months each year (Jaensch 2005 pers. comm.). This strongly suggests that the Australasian Bittern is capable of moving between wetlands as the suitability of habitats change (Garnett 1992; Garnett & Crowley 2000).

The Australasian Bittern is difficult to detect visually; it has camouflage-like plumage and occupies wetlands with dense vegetation. If disturbed, it may adopt a cryptic 'freeze' posture in which it stands with plumage compressed, bill pointing vertically and eyes pointing downwards towards the disturbance; on windy days, it may even sway to match the movement of the vegetation (Heather & Robertson 1997; Jaensch 2005 pers. comm.; Marchant & Higgins 1990). Alternatively, it may drop slowly into the vegetation by retracting the head and crouching down (Heather & Robertson 1997). For these reasons, it is more often heard than seen. Advertising calls may be detected up to 800-1000 m away (Marchant & Higgins 1990; Jaensch 2005 pers. comm.). At close range, the Australasian Bittern can be heard emitting several short gasps followed immediately by several deep resonant 'booms'. This series of calls is delivered over a period 10-15 seconds (Jaensch 2005 pers. comm.). The distinctive booming call of the Australasian Bittern could be confused with that of the Purple Swamphen (Porphyrio porphyrio) if observers are unfamiliar with the calls, a long way from the calling bird or surveying during windy conditions. It may even be confused with bellowing calls of distant cattle (Marchant & Higgins 1990).

The Australasian Bittern is only likely to be confused visually with other smaller bitterns or immature night herons (Marchant & Higgins 1990). It is superficially similar to the juvenile Nankeen Night Heron (Nycticorax caledonicus) but the Australasian Bittern is much larger and has mottled camouflage-like plumage, as opposed to the boldly spotted and streaked plumage of the immature Nankeen Night Heron (Jaensch 2005 pers. comm.; Marchant & Higgins 1990; Pizzey & Knight 1997). Unlike the Nankeen Night Heron, the Australasian Bittern also normally does not perch or roost in trees (R. Jaensch June 2005, pers. comm.; Marchant & Higgins 1990). The Black Bittern (Ixobrychus flavicollis), which is sympatric with the Australasian Bittern in far eastern Victoria, coastal New South Wales and south-east Queensland, is much smaller, generally more graceful and has a uniformly dark brown to black dorsum. Furthermore, the Black Bittern is found mainly in wooded habitats, such as trees and shrubs overhanging coastal creeks, where the Australasian Bittern is unlikely to occur (Jaensch 2005 pers. comm.; Marchant & Higgins 1990).

In most habitats, the recommended method for surveying the Australasian Bittern is by nocturnal survey with detection by call. Surveys should be conducted during the spring-summer breeding season (Jaensch 2005 pers. comm.), when calls are most often heard (Marchant & Higgins 1990). Surveys would be most effective during calm weather. It is recommended that each site be surveyed for a minimum of 1 hour listening time. This method allows many wetlands to be surveyed in a short period of time. It is unlikely that all birds present at a site will call (Jaensch 2005 pers. comm.) and therefore this method is likely to underestimate population size.

In temporary wetlands it may be possible to count aggregations of birds when the waters become shallow prior to drying out. In such habitats, area searches are recommended (population densities may be too low for transect surveys). Observers should systematically cover as much habitat as possible whilst wading through the wetland to flush concealed birds. Wading should be focused in vegetation that allows observers to observe bitterns that may flush several metres ahead (Jaensch 2005, pers. comm.).

The major threat to the Australasian Bittern is habitat loss and degradation, due mainly to drainage or filling-in of wetlands, river regulation and diversion of water away from wetlands for agriculture. High levels of grazing, salinisation of swamps, collisions with man-made structures and shooting are additional factors likely to be contributing to the species’ decline (BirdLife International 2000a, 2004; Garnett & Crowley 2000; Heather & Robertson 1997; Jaensch 2005 pers. comm.; Marchant & Higgins 1990).

Over the last 100 years, many suitable wetland sites in both south-eastern and south-western Australia have been lost because of hydrological changes (Jaensch 2005 pers. comm.). The distribution of the Australasian Bittern in Australia is severely fragmented due to the species' narrow habitat preferences (i.e. densely vegetated wetlands) and the ongoing loss or alteration of suitable habitat. In south-eastern Australia, cessation of floodplain inundation due to water harvesting and alteration of drainage systems has destroyed much of the Australasian Bittern's seasonal habitat (Jaensch 2004). Many of the Murray-Darling wetlands are no longer available or are rarely available for use by the species, due to river regulation and water harvesting (Jaensch 2005 pers. comm.). The clearing of wetlands for urbanisation or agriculture has also had a significant impact. In Queensland, clearing of coastal wetlands for urbanisation, particularly around the Sunshine Coast, has greatly reduced the species’ area of occupancy. In NSW, much of the Gwydir floodplain has been cleared and converted for agriculture, leaving only very small areas of suitable habitat (Jaensch 2005 pers. comm.).

The Australasian Bittern tends to be more sensitive to habitat loss than many other wetland birds (Garnett & Crowley 2000). Although many sites occupied by Australasian Bitterns are now protected, the species continues to be threatened by the processes associated with past declines. The threat posed by the clearing of habitat for urbanisation may have declined in NSW in recent years (due to the implementation of that state's State Environmental Planning Policy No. 14), however the coastal zone in Australia is subject to intense and escalating pressure from housing, semi-rural and other developments (Jaensch 2004).

In south-western Australia, salinisation of inland swamps due to vegetation clearing has resulted in these swamps becoming unsuitable for the Australasian Bittern (Jaensch 2004). Harvesting of groundwater has also contributed to the contraction of the species' range in Western Australia (Jaensch 2005 pers. comm.). Other factors that have affected the suitability and availability of wetland habitats since European settlement include siltation and pollution, overgrazing by livestock, peat mining and inappropriate fire regimes (a swamp near Albany, Western Australia, was deserted for two years after fire) (Garnett & Crowley 2000; Marchant & Higgins 1990; Smith et al. 1995). The European Red Fox (Vulpes vulpes) is known to prey upon the Australasian Bittern’s eggs and juvenile individuals (Smith et al. 1995); however, the impact of this threat has not been quantified.

Conservation of the current Australasian Bittern population requires the maintenance of suitable wetland habitats. For many locations, the top priority is to ensure that a suitable water regime is maintained or established. At present, Fivebough Swamp in NSW, Bool Lagoon in South Australia and Lake Muir and its surrounding wetlands in Western Australia are managed to benefit the resident Bittern populations (Garnett & Crowley 2000; R. Jaensch June 2005, pers. comm.). Further recommended management actions include:

  • Research to establish more accurate population estimates and to provide more detail on habitat and drought refuge requirements, diet, predators, breeding range and movements.
  • Identification, protection and management of habitat, including principal breeding wetlands.
  • Rehabilitation of selected former breeding habitats.
  • Control of feral animals, particularly foxes and cats.
  • Development of appropriate guidelines for wetland management.
  • Involvement of community groups and bird associations in the collection of information (Garnett & Crowley 2000; Smith et al. 1995).

Documents relevant to the management of the Australasian Bittern can be found at the start of the profile.

The following table lists known and perceived threats to this species. Threats are based on the International Union for Conservation of Nature and Natural Resources (IUCN) threat classification version 1.1.

Threat Class Threatening Species References
Agriculture and Aquaculture:Agriculture and Aquaculture:Land clearing, habitat fragmentation and/or habitat degradation The Action Plan for Australian Birds 2000 (Garnett, S.T. & G.M. Crowley, 2000) [Cwlth Action Plan].
Commonwealth Listing Advice on Land clearance (Threatened Species Scientific Committee, 2001w) [Listing Advice].
Agriculture and Aquaculture:Livestock Farming and Grazing:Grazing pressures and associated habitat changes Commonwealth Listing Advice on Botaurus poiciloptilus (Australasian Bittern) (Threatened Species Scientific Committee (TSSC), 2011v) [Listing Advice].
Regional Recovery Plan for Threatened Species & Ecological Communities of Adelaide and Mount Lofty Ranges 2009-2014 (Willson, A. & J. Bignall, 2009a) [State Recovery Plan].
Climate Change and Severe Weather:Climate Change and Severe Weather:Climate change altering atmosphere/hydrosphere temperatures, rainfall patterns and/or frequency of severe weather events Regional Recovery Plan for Threatened Species & Ecological Communities of Adelaide and Mount Lofty Ranges 2009-2014 (Willson, A. & J. Bignall, 2009a) [State Recovery Plan].
Climate Change and Severe Weather:Habitat Shifting and Alteration:Habitat loss, modification and/or degradation Commonwealth Listing Advice on Botaurus poiciloptilus (Australasian Bittern) (Threatened Species Scientific Committee (TSSC), 2011v) [Listing Advice].
Climate Change and Severe Weather:Habitat Shifting and Alteration:Habitat modification, destruction and alteration due to changes in land use patterns Commonwealth Listing Advice on Botaurus poiciloptilus (Australasian Bittern) (Threatened Species Scientific Committee (TSSC), 2011v) [Listing Advice].
Human Intrusions and Disturbance:Recreational Activities:Disturbance, especially from human recreational activities and development Regional Recovery Plan for Threatened Species & Ecological Communities of Adelaide and Mount Lofty Ranges 2009-2014 (Willson, A. & J. Bignall, 2009a) [State Recovery Plan].
Invasive and Other Problematic Species and Genes:Invasive Non-Native/Alien Species:Competition and/or predation Vulpes vulpes (Red Fox, Fox) Commonwealth Listing Advice on Botaurus poiciloptilus (Australasian Bittern) (Threatened Species Scientific Committee (TSSC), 2011v) [Listing Advice].
Regional Recovery Plan for Threatened Species & Ecological Communities of Adelaide and Mount Lofty Ranges 2009-2014 (Willson, A. & J. Bignall, 2009a) [State Recovery Plan].
Invasive and Other Problematic Species and Genes:Invasive Non-Native/Alien Species:Competition and/or predation Felis catus (Cat, House Cat, Domestic Cat) Commonwealth Listing Advice on Botaurus poiciloptilus (Australasian Bittern) (Threatened Species Scientific Committee (TSSC), 2011v) [Listing Advice].
Regional Recovery Plan for Threatened Species & Ecological Communities of Adelaide and Mount Lofty Ranges 2009-2014 (Willson, A. & J. Bignall, 2009a) [State Recovery Plan].
Invasive and Other Problematic Species and Genes:Invasive Non-Native/Alien Species:Competition and/or predation Canis lupus familiaris (Domestic Dog) Regional Recovery Plan for Threatened Species & Ecological Communities of Adelaide and Mount Lofty Ranges 2009-2014 (Willson, A. & J. Bignall, 2009a) [State Recovery Plan].
Natural System Modifications:Dams and Water Management/Use:Alteration of hydrological regimes and water quality Regional Recovery Plan for Threatened Species & Ecological Communities of Adelaide and Mount Lofty Ranges 2009-2014 (Willson, A. & J. Bignall, 2009a) [State Recovery Plan].
Natural System Modifications:Dams and Water Management/Use:Alterations to hydrology through water extraction Commonwealth Listing Advice on Botaurus poiciloptilus (Australasian Bittern) (Threatened Species Scientific Committee (TSSC), 2011v) [Listing Advice].
Natural System Modifications:Dams and Water Management/Use:Changes in hydrology including habitat drainage Commonwealth Listing Advice on Botaurus poiciloptilus (Australasian Bittern) (Threatened Species Scientific Committee (TSSC), 2011v) [Listing Advice].
Natural System Modifications:Dams and Water Management/Use:Changes to hydrology including construction of dams/barriers Commonwealth Listing Advice on Botaurus poiciloptilus (Australasian Bittern) (Threatened Species Scientific Committee (TSSC), 2011v) [Listing Advice].
Natural System Modifications:Dams and Water Management/Use:Extraction of ground water Commonwealth Listing Advice on Botaurus poiciloptilus (Australasian Bittern) (Threatened Species Scientific Committee (TSSC), 2011v) [Listing Advice].
Natural System Modifications:Fire and Fire Suppression:Inappropriate and/or changed fire regimes (frequency, timing, intensity) Commonwealth Listing Advice on Botaurus poiciloptilus (Australasian Bittern) (Threatened Species Scientific Committee (TSSC), 2011v) [Listing Advice].
Regional Recovery Plan for Threatened Species & Ecological Communities of Adelaide and Mount Lofty Ranges 2009-2014 (Willson, A. & J. Bignall, 2009a) [State Recovery Plan].
Natural System Modifications:Fire and Fire Suppression:Inappropriate prescribed regimes and/or vegetation management to control fire regimes Regional Recovery Plan for Threatened Species & Ecological Communities of Adelaide and Mount Lofty Ranges 2009-2014 (Willson, A. & J. Bignall, 2009a) [State Recovery Plan].
Pollution:Pollution:Changes to water and sediment flows leading to erosion, siltation and pollution Commonwealth Listing Advice on Botaurus poiciloptilus (Australasian Bittern) (Threatened Species Scientific Committee (TSSC), 2011v) [Listing Advice].
Pollution:Pollution:Declining water quality (salinity, nutrient and/or turbitity) Commonwealth Listing Advice on Botaurus poiciloptilus (Australasian Bittern) (Threatened Species Scientific Committee (TSSC), 2011v) [Listing Advice].
Pollution:Pollution:Pollution due to oil spills and other chemical pollutants Regional Recovery Plan for Threatened Species & Ecological Communities of Adelaide and Mount Lofty Ranges 2009-2014 (Willson, A. & J. Bignall, 2009a) [State Recovery Plan].
Residential and Commercial Development:Housing and Urban Areas:Habitat loss, modification and fragmentation due to urban development Commonwealth Listing Advice on Botaurus poiciloptilus (Australasian Bittern) (Threatened Species Scientific Committee (TSSC), 2011v) [Listing Advice].
Regional Recovery Plan for Threatened Species & Ecological Communities of Adelaide and Mount Lofty Ranges 2009-2014 (Willson, A. & J. Bignall, 2009a) [State Recovery Plan].

Birdlife International (2000a). Threatened Birds of the World. Barcelona, Spain & Cambridge, UK: BirdLife International & Lynx Edicions.

BirdLife International (2004). Species factsheet: Botaurus poiciloptilus. [Online]. Available from: http://www.birdlife.org.

Birds Australia (2005). Personal Communication, August 2005.

Christidis, L. & W.E. Boles (1994). The Taxonomy and Species of Birds of Australia and its Territories. Royal Australasian Ornithologists Union Monograph 2. Melbourne, Victoria: Royal Australasian Ornithologists Union.

Delany, S. & D. Scott (2002). Waterbird Population Estimates. Wetlands International, Wageningen, the Netherlands. Wetlands International Global Series 12. 3.

FTWMTI (2002). Management Plan for Fivebough and Tuckerbill Swamps. [Online]. Leeton, NSW. Available from: http://www.fivebough.org.au/pdfs/objectives.pdf.

Garnett, S., J. Szabo & G. Dutson (2011). The Action Plan for Australian Birds 2010. CSIRO Publishing.

Garnett, S.T. (1992). Threatened and Extinct Birds of Australia. RAOU Report 82. RAOU, Melbourne & ANPWS, Canberra.

Garnett, S.T. & G.M. Crowley (2000). The Action Plan for Australian Birds 2000. [Online]. Canberra, ACT: Environment Australia and Birds Australia. Available from: http://www.environment.gov.au/biodiversity/threatened/publications/action/birds2000/index.html.

Heather, B.D. & H.A. Robertson (2000a). The Field Guide to the Birds of New Zealand. Oxford, United Kingdom: Oxford University Press.

Herring, M. & A. Silcocks (2014). I'd like to order some bitterns and rice, please. Wetlands Australia. February:12-13.

IUCN (2004a). 2004 IUCN Red List of Threatened Species. [Online]. Available from: http://www.redlist.org. [Accessed: 07-Jun-2005].

Jaensch, R. (2004). Australasian Bittern. Wingspan. 14(4).

Jaensch, R. (2005). Personal Communcation, June 2005.

Jaensch, R.P. & R.M. Vervest (1988a). Ducks, Swans and Coots in south-western Australia: the 1986 and 1987 counts. RAOU Report Series. 31:1-32.

Jaensch, R.P., R.M. Vervest & M.J. Hewish (1988). Waterbirds in nature reserves of south-western Australia 1981-1985: reserve accounts. RAOU Report Series. 30.

Marchant, S. & P.J. Higgins, eds. (1990). Handbook of Australian, New Zealand and Antarctic Birds. Volume One - Ratites to Ducks. Melbourne, Victoria: Oxford University Press.

Menkhorst, P. (2012). The food and foraging rate of an Australasian Bittern. Australian Field Ornathology. 29:133-142.

NSW NPWS (1999). Atlas of New South Wales Wildlife. NPWS. Hurstville.

Pickering, R. (2013). The Australasian bittern and its water requirements. Wetlands Australia. Feb:25-26.

Pizzey, G. & F. Knight (1997). The Graham Pizzey and Frank Knight Field Guide to the Birds of Australia. Sydney: Angus & Robertson.

Serventy, D.L. & H.M. Whittell (1976). Birds of Western Australia. Perth: University of Western Australia Press.

Smith, P.J., J.E. Smith, R.L. Pressey & G.L. Whish (1995). Birds of Particular Conservation Concern in the Western Division of New South Wales: Distribution, Habitats and Threats. NSW NPWS, Hurstville.

Threatened Species Scientific Committee (TSSC) (2011v). Commonwealth Listing Advice on Botaurus poiciloptilus (Australasian Bittern). [Online]. Department of Sustainability, Environment, Water, Population and Communities. Canberra, ACT: Department of Sustainability, Environment, Water, Population and Communities. Available from: http://www.environment.gov.au/biodiversity/threatened/species/pubs/1001-listing-advice.pdf.

Whiteside, A.J. (1989). The behaviour of bitterns and their use of habitat. Notornis. 36:89-95.

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This database is designed to provide statutory, biological and ecological information on species and ecological communities, migratory species, marine species, and species and species products subject to international trade and commercial use protected under the Environment Protection and Biodiversity Conservation Act 1999 (the EPBC Act). It has been compiled from a range of sources including listing advice, recovery plans, published literature and individual experts. While reasonable efforts have been made to ensure the accuracy of the information, no guarantee is given, nor responsibility taken, by the Commonwealth for its accuracy, currency or completeness. The Commonwealth does not accept any responsibility for any loss or damage that may be occasioned directly or indirectly through the use of, or reliance on, the information contained in this database. The information contained in this database does not necessarily represent the views of the Commonwealth. This database is not intended to be a complete source of information on the matters it deals with. Individuals and organisations should consider all the available information, including that available from other sources, in deciding whether there is a need to make a referral or apply for a permit or exemption under the EPBC Act.

Citation: Department of the Environment (2014). Botaurus poiciloptilus in Species Profile and Threats Database, Department of the Environment, Canberra. Available from: http://www.environment.gov.au/sprat. Accessed Wed, 3 Sep 2014 04:04:41 +1000.