Conservation issues

Flock bronzewing pigeons can occur episodically in suitable grassland or floodplain habitats in response to favourable conditions Photo: Graeme Chapman

Male bustards return to the same sites in the northern savannas to display year after year. They spend much of the breeding season displaying Photo: Steve Wilson

Our online survey to help track two of Australia's most elusive birds—the flock bronzewing pigeon and the Australian bustard—is currently complete. Thank you to those who filled out our survey form. Most responses came from mail-out surveys; results can be found at the end of the page.

Highly mobile species

Rapid changes in populations of many animals are particularly apparent in Australia’s monsoonal and arid regions, where birds such as flock bronzewing pigeons ( Phaps histrionica ) and Australian bustards ( Ardeotis australis ) can turn up after not being seen for several years. These highly mobile species can track favourable conditions over vast distances, responding to fluxes in resources with large and rapid population increases.

Their mobility makes them hard to study, but understanding their movements is important if we are going to ensure their survival. We need to know that the resources that enable them to do well in good years, and hang on in bad years, continue to be available. To do this, we need to know where they are found at different parts of the climate cycle: their movements and population dynamics at local, regional and landscape scales.

Research methods

Collection of such information using conventional methods is exceedingly difficult. However, the development of large-scale, community-based bird surveys (including mail surveys of rangeland users) and new technologies, such as satellite telemetry and spatial information systems, is now making collection of detailed data on movements and population fluctuations, and the factors that trigger them, possible.

Using such techniques, two Northern Territory based scientists are undertaking studies of the movements and ecology of the Australian bustard and the flock bronzewing pigeon.

The studies

The overall aim of these projects is to use these focal species as models for developing innovative techniques for examining the distributions and movements of highly mobile, nomadic species and monitoring the status of both the species and their habitats over landscape scales. Complementing this broad-scale approach is an investigation of the ecology of each species at specific sites to provide a holistic picture of how such species operate and therefore how we may cater for their protection at local, regional and landscape scales.

Australian bustard

The Australian bustard is an easily identifiable and iconic species across outback Australia. It undergoes significant population fluctuations and movements in response to prevailing conditions.

Mark Ziembicki , of the University of Adelaide and the Biodiversity Conservation Unit of the Northern Territory’s Department of Natural Resources, Environment and the Arts, has been studying the movements of the Australian bustard for some years using satellite tracking techniques. Results of a continental-scale mail survey of rangeland users in 2002, aimed at documenting distribution patterns of bustards across Australia , have contributed to the picture of how these birds are distributed across the landscape.

Estimates of Australian Bustard numbers reported from 679 properties across Australia in 2002 showed highest concentrations across the northern savanna regions from the Pilbara in Western Australia to central Queensland.

Flock bronzewing pigeon

The flock bronzewing pigeon is another iconic species of the open rangelands of northern Australia, known for their nomadic habits and for sporadic and infrequent spectacular aggregations. Populations fluctuate dramatically throughout space and time and they are known as a 'boom-bust' species. They can be locally abundant following good seasons but then vanish and may not reappear in the area for decades.

Peter Dostine, of the Australian National University and the Biodiversity Conservation Unit of the Northern Territory ’s Department of Natural Resources, Environment and the Arts, has begun a project which aims to integrate data on resource patterning from satellite imagery, movement data from birds tagged with satellite transmitters and information on patterns of abundance from community-based surveys of rangeland users.

A mail-out survey of rangeland users yielded excellent information on distribution (Figure 1) and long-term patterns of abundance (Figure 2). Results suggest that populations are dynamic and linked to infrequent heavy rainfall events and major floods.

Years reported as 'Best for flock bronzewings' coincide with periods of above average rainfall and major floods.

Distribution of mail survey responses showing properties where flock bronzewing pigeons were reported as present, and those reported as absent