Eastern bristlebird Photo: EHP
Common name: eastern bristlebird
Scientific name: Dasyornis brachypterus
Conservation status: This species is listed as Endangered in Queensland (Nature Conservation Act 1992) and nationally (Environment Protection and Biodiversity Conservation Act 1999). It is considered a high priority for conservation under the Department of Environment and Heritage Protection Back on Track species prioritisation framework.
The eastern bristlebird is a small ground-dwelling bird approximately 20 cm long with the tail accounting for about one-half of its total length. It may look like just another small, brown bird but if you look closely you will see features such as the short wings, strong legs, and distinct bristles in front of the eyes that are perfect adaptations for living amongst dense ground vegetation. The bird is primarily brown with rufous flight feathers, a paler and greyer underside and a pale face with red eyes. The tail appears frayed and is sometimes raised and fanned.
Habitat and distribution
Today, the eastern bristlebird is restricted to three geographically separate areas along eastern Australia. The smallest and most northern occurrence is in the Border Ranges of south-eastern Queensland and adjacent parts of north-east New South Wales. This small group is endangered. Observers have found that the birds in this population look different from their southern cousins, however genetic research has suggested that this population is not a sub-species.
The northern population of the eastern bristlebird lives in moist, mountain ranges within about 100 km of the coast. In Queensland most sightings have been within localised pockets of relatively open eucalypt forest in close proximity to denser vegetation along creek lines and rainforest. Soils are relatively fertile, derived from basalts of the Main Range Volcanics and Mt Warning Shield. However, a colony at Mt Barney lives in shrubby montane heath vegetation on poorer soils and a colony once occupied similar habitat near Surprise Rock in Lamington National Park.
The ground stratum of the eucalypt forests favoured by the eastern bristlebird is a mosaic of dense clumped grasses interspersed with patches of shrubs, ferns, tangled vines and fallen logs. The more common grasses include wild sorghum (Sarga leiocladum), kangaroo grass (Themeda triandra) and tussock grass (Poa labillardieri). The presence of mature wild sorghum tussocks is thought to be a good indicator of high quality bristlebird habitat.
Life history and behaviour
Eastern bristlebird eggs Photo: Grant Fraser
The eastern bristlebird lives a secretive life, foraging and nesting in thick ground foliage. Its elusive nature means that you are unlikely to see it, although you may hear it. This plucky little bird uses a distinctive and loud melodic song to mark its territory and warn other eastern bristlebirds to "back off".
The eastern bristlebird obtains food mainly from the ground by probing the surface, though they may also glean foliage or snatch flying insects. Food items include insects (e.g. ants, bugs, beetles and orthopterans), seeds, small fruits and earthworms.
Birds are active by day but sedentary, spending the majority of time hidden amongst low dense vegetation. Calling begins after sunrise, often after rain. Like many other birds, eastern bristlebirds do not appear to like cool mornings and are reluctant to call when conditions are unfavourable. Males usually call from on top of a conspicuous ‘calling’ log within their territory. If a female is in the territory, she will often respond, but it can be difficult for the untrained ear to distinguish between the two calls. Throughout the day, both birds keep in contact with short ‘clicks’ known as contact calls.
Breeding pairs establish permanent territories of 1-4 ha with calling birds 100-300 m apart. The breeding season extends from late July to February. During this time a female may produce several clutches of eggs. A clutch is usually two eggs with one successful brood (of only one chick) raised per year. Time of breeding varies depending on weather, with timing most likely triggered by storms or heavy rain, which stimulate grass growth and insect activity.
A nest is constructed by the female over a few days. It is built just above the ground amongst shelter. After construction, the two eggs are laid 24 hours apart. The eggs are cream coloured with a pinkish tinge and are heavily spotted with brown and purplish brown. Incubation of bristlebird eggs takes approximately 21 days and is performed by the female. The male brings food to the female during incubation. Nests disturbed during incubation are readily abandoned.
After the eggs hatch, the male undertakes the majority of the feeding of the young. The female does all of the brooding of the chicks. After about 13 days the first feathers begin to erupt from the pin feathers. After another four or five days, the chicks fledge and are thereafter dependant on the male and have very little to do with the female. If conditions are favourable after the chicks fledge, the female will begin to construct a new nest after about three days. After a further 18 days (36 days after hatching) the chicks are fully independent.
The eastern bristlebird has developed effective tactics to survive in its fire-prone environment. During fires, adult birds take refuge in the nearby rainforest, though eggs and nestlings may be destroyed if fire occurs during the breeding season in spring. With their short wings, the eastern bristlebird is unable to fly great distances to find new places to live. If habitat is damaged or destroyed, the birds may not be able to reach nearby areas of suitable habitat not already occupied by other eastern bristlebirds.
Tussocks of wild sorghum Photo: Rowena Thomas
It is believed that inappropriate fire regimes and changes to the habitat structure in key habitats are the main threat to the northern (Queensland/New South Wales) population of eastern bristlebirds. Fire destroys cover, but infrequent fire can also cause shrub and tree density to become too high. However, if birds are not able to move from their existing habitat to new areas whilst an area is immediately affected by fire, birds can perish either during or after a fire.
Other possible threats include overgrazing, invasion of habitat by exotic plants and disturbance by humans. Inappropriate grazing, habitat damage by recreational 4WDs and illegal collection of eggs have also been listed as possible threats. Severe disturbance by wildlife is known to have caused localised extinction of the eastern bristlebird previously.
An eastern bristlebird site showing (1) the understorey prior to a planned burn, (2) soon after the fire and (3) in recovery several months later Photos: Rowena Thomas
Planned use of fire seems to be the best way to guarantee that some of the important components of eastern bristlebird habitat, especially tussock grasses, continue to be available in the places where they live. However, deliberate use of fire on a regular basis can also cause changes to the vegetation that do not necessarily benefit the eastern bristlebird. An example is the replacement of preferred grass species by fire tolerant species such as blady grass Imperata cylindrica. Finding a balance with regards to timing, frequency and extent of fire is crucial to the eastern bristlebird's future as well as for a range of other threatened species that live in similar habitat (e.g. Hastings River mouse and the vine Marsdenia longiloba).
A large group of scientists, rangers, volunteers and land managers has been striving to ensure the eastern bristlebird survives within southeastern Queensland by:
- searching for the eastern bristlebird and understanding its behaviour and habitat requirements
- protecting eastern bristlebird habitat occurs on national park and private land
- attempting to understand the possible reasons for the population declines so that management actions can be refined.
Future management actions that are required include:
- Establishing and maintaining a viable captive population for release into the northern population
- Preparing and implementing fire management plans for all populations
- Developing contingency plans in case of fire including emergency evacuations, assisted habitat recovery and translocations
- Control foxes and cats where vulnerable to predation
- Control weeds that are incompatible with bristlebirds
- Undertake further translocations and reintroductions.
Curtis LK, Dennis AJ, McDonald KR, Kyne PM, and Debus SJS. (2012) Queensland’s Threatened Animals, CSIRO, Victoria, Australia.
Garnett ST, Szabo JK, and Dutson G. (2011) The Action Plan for Australian Birds 2010, CSIRO, Victoria, Australia.