Tropical Savannas CRC > Education & Training > PhD Projects: 2001-2007 > Ecology and Conservation of the Australian Bustard

TS-CRC Student project - Ecology and conservation of a nomad: A case study using the Australian bustard

University of Adelaide

Mark Ziembicki

Summary | Landscape-scale distribution and monitoring | Habitat use, feeding and reproductive ecology | Exploded lek mating system | Movements | Techniques for monitoring growth pulses | Aboriginal knowledge and harvesting | Supervisors |


Terms used on this page:

Nomadic: fauna that move in an opportunistic ways across the landscape, usually in response to factors such as rainfall, fire etc.

Dispersive: movements made following breeding where large numbers of birds disperse from breeding areas.

Irruptive: Describes an organism that can demonstrate a sudden change in the density of its population.

Off-reserve conservation:
Conservation activities that take place outside designated parks and reserves.

  Australian bustard
Australian bustard: large, conspicuous and with some interesting mating habits
Photo: Mark Ziembicki

Summary

A large proportion of birds in the monsoonal and arid grasslands of Australia are characterised by dispersive, nomadic movements and large population fluctuations in response to variable climatic conditions. These characteristics, along with poor knowledge of the movements of Australian birds, make monitoring their populations complicated. Conservation and reserve design for such species are also difficult since there is no guarantee that an area set aside for conserving them will remain suitable through time.

This project aims to use a typical nomad, the Australian bustard, to develop methodology that will help monitor the distribution, movements and status of such highly mobile birds and their habitats on landscape scales and thereby aid in off-reserve conservation of highly mobile populations.

This broad scale approach is complemented by a detailed investigation of the ecology of the species at selected sites in northern Australia in relation to key threatening processes, including altered fire regimes, grazing impacts, hunting and habitat alteration due to woody weed infestation. Additionally, documenting Aboriginal knowledge of the status, distribution and ecology of the species and current harvest rates is an important part of the project.

Landscape-scale distribution and monitoring

Bustards are particularly suitable to a study of responses by birds to climatic variability on a landscape-scale because of their conspicuousness (therefore they are readily identifiable by landowners), large size (enabling radio and satellite tracking), existing databases of bustard distribution, and their nomadic, irruptive nature.

Furthermore, the species is representative of a suite of birds that have undergone significant population declines in the northern and arid grassland regions of Australia.

This component of the study aims to develop and assess techniques for efficiently monitoring the growth pulse in arid and monsoonal grasslands, with an emphasis on its use for detecting the widely scattered, ephemeral and temporally variable habitat of breeding bustards. Such areas can then be targeted for protection and management at critical times in the bustard's life cycle. Distributional data for bustards collated from numerous sources will be related to mapped landscape features and remotely sensed data that measure and compare growth pulses at particular sites and over broad landscape and temporal scales.

Progress in 2002–3

Distributional data for bustards has been collected and includes information from large scale mail surveys to remote pastoral and other landholder properties in rangeland WA, SA, NT, Qld and western NSW. Other sources of information have come from the Birds Australia Atlas surveys, state and territory government agency record schemes and museum records. Compilation of remote sensing and mapping information is almost complete and final analyses are due for completion by November 2003.

Habitat use and feeding and reproductive ecology

A detailed, site-specific investigation into the ecological relationships between bustards and different fire regimes, land uses and land productivity, especially as these relate to the species feeding and reproductive ecology is under way at two sites of varying rainfall; the Victoria River District and the Douglas-Daly River regions. Assessment of habitat use, diet and food resource availability in different habitats in relation to fire history and grazing is an important part of this work.

Bustard rustling his feathers for the girls Bustard displaying for the girls

A couple of male bustards step out to impress the females
Photos: Mark Ziembicki

Exploded lek mating system

Bustards are unique among Australia's birds in that they exhibit what is known as an exploded lek mating system. Leks are aggregations of males that come together to display in specific areas, which females in turn visit to find mates—sort of like the local pub! The difference being that males are usually well separated from each other and are more spectacularly dressed than the ladies.

It's an exploded lek because males are usually well spaced apart—from 100m up to a kilometre. Generally, among lekking species it's the larger males, with more elaborate displays, that are more successful in the mating game.

This has important implications for harvesting bustards, because if bigger birds, (the larger, more successful males) are preferred for harvest, then the breeding performance of the species as a whole may suffer.

Just as we have our preferred watering holes so too bustards may have preferred breeding or lekking sites. If this is the case then those areas are of vital importance for protecting the species. Accordingly, one aim of my research is to determine whether individuals keep to preferred breeding and lekking sites over time.

To perform their elaborate displays males prefer open areas of good visibility so females can see them. For this reason, the birds may benefit (to some extent) from grazing and periodic fires, which open up country. Females may then preferentially seek nesting sites within more sheltered, vegetated areas within the general area, which they especially require when raising young, who are almost immediately mobile. A variety of habitats in a breeding area may therefore be an advantage to bustards.

Progress in 2002-3

Progress in the past year has focused on continuing the study of the species ecology. Information has been collected on the diet and habitat use of bustards and the seasonal variability in bustard numbers at each site. Intensive field work during the following breeding season commencing in September will focus on the breeding biology of the species in addition to work already in progress on other aspects of the bustard's ecology.

Movements

Local-scale movements and ranging behaviour are currently being investigated using radiotelemetry and marking of individual bustards using wing tags with particular emphasis on determining responses to experimentally induced fires, delineating daily activity and habitat use patterns and determining territory sizes, particularly with regard to configuration and use of leks. A grant through the Herman Slade Foundation was obtained in early 2003 to facilitate satellite tracking of individual bustards in the arid and monsoonal grasslands regions of northern Australia. This work is due to commence in August and aims to identify large scale movements and possible cues for so-called nomadic movements in relation to primary productivity, rainfall, fire management, grazing intensity and horticultural developments on landscape-scales.

Techniques for monitoring growth pulses

This component of the study aims to develop and assess techniques for efficiently monitoring the growth pulse in arid and monsoonal grasslands, with an emphasis on detecting the widely scattered, ephemeral and temporally variable habitat of breeding bustards.

Distributional data for bustards collated from numerous sources, including bird atlases, government fauna record schemes, aerial surveys and a large mail-out survey to remote properties, will be related to remotely sensed data that measure and compare growth pulses at particular sites and over broad landscape and temporal scales.

Mapped features that may influence bustard habitat use in the form of GIS layers and a digital elevation model (to account for topographical preferences) will be incorporated into the analysis. This information should allow for the development of a tool for predicting and locating optimal habitat for bustards and thereby aid in targeting specific areas for protection and management at critical times in the bustard's life cycle.

Aboriginal knowledge and harvesting

Bustards are an important cultural and food resource to many Aboriginal communities throughout central and northern Australia. The decline of bustards in these regions, which has been partly attributed to breakdown over controls of traditional hunting, is of concern to many indigenous communities. Part of the project therefore seeks to:

  • determine whether such concerns are justifiable in the study site regions,
  • draw on the knowledge and perspectives of Aboriginal communities regarding the status, distribution and ecology of the species
  • examine changes in bustard numbers in specific areas over time, and to
  • determine whether current harvest rates are sustainable
Progress in 2002–3

Communities and Aboriginal land care units are involved in the project in the two main study regions. Work to date has focussed on collecting information on the status, distribution, habitat use and diet of bustards from knowledge of individuals and from collection of stomach contents from birds harvested.

It is hoped that this research, by assessing the ecology and habitat requirements of bustards, in conjunction with a landscape-scale analysis of their distribution and movements, will improve our knowledge of the conservation and management requirements of the species, as well as our understanding of ground-dwelling birds and other nomadic species and their habitats in Australia's arid and monsoonal grasslands.

Supervisors

Dr John Woinarski, NT DIPE
Dr David Paton, Adelaide University

Contacts

Mr Mark Ziembicki
PhD Student
Department of Natural Resources, Environment and The Arts
Tel: 08 8995 5000

Fax: 08 8995 5099

PO Box 496
PALMERSTON, NT 0831