Key Findings
Thursday, February 9th, 2012
Identifying and tracking the birds
Chicks and adults are being colour-banded and fitted with satellite transmitters. Two colours identify the bird’s broader region (one of four regions) and specific area, and each bird has a specific letter/ number code. Satellite transmitters collect locations using GPS technology four times per day and send these data back to the researcher via satellite once a week.
Research progress to date
Prior to December 2009 an aerial survey to find brolga nest sites was undertaken. Since late November 2009, 22 brolgas have been fitted with transmitters. This includes 11 pre-fledged chicks, five adults and six juveniles. Fourteen transmitters are still providing data. Introducing these transmitters over a year and a half means data has been collected across age cohorts, seasons and years.
Key research findings to November 2011:
Seasonal movements between non-breeding and breeding sites
Eight individual brolgas provided data on seasonal movements. These birds departed the non-breeding grounds of Willaura and Penshurst in late May to early July in 2010 and 2011. Seven of these moved approximately 100 km west and south west to an area near Casterton and Dartmoor. One individual also moved to this area, but flew back north east and settled near the Grampians.
Dispersal of chicks from breeding grounds
Leg band mounted transmitters were fitted on 11 pre-fledged brolga chicks between November 2010 and March 2011. All survived to fledging and dispersal. Nine of these have survived to date. Two individuals died shortly after leaving their breeding site.
Most of the chicks remained near their breeding grounds through the flocking period. The first fledglings began leaving their breeding area in March, with most fledglings leaving between June-August. Two individuals still remained near breeding sites in August.
Habitat use, home ranges and spatial requirements
Up to four GPS locations per day are being logged for each individual, providing detailed information about feeding and roosting habitats. Analysis of this data will begin in early 2012.
Survival of chicks, juveniles and adults
Nineteen pre-fledged chicks have been banded during the project, 11 of which have been fitted with transmitters. All these chicks survived to fledging and dispersal, indicating that chick survival can be high if breeding sites have water for the duration of the hatching to fledging period.
The data from birds fitted with transmitters indicate that adult and juvenile survival is also generally high.
Brolga counts
The Department of Sustainability and Environment has been coordinating counts of brolgas in southwest Victoria for the past three years to get a better understanding of how many brolgas there are in the southwest and how much successful breeding is happening.
Key brolga count findings to July 2010:
- 401 Brolgas were found at five flocking sites in May, of which between nine and 16% of flocks were young birds less than one year old.
- This compares favourably with the previous year 2008 when only 3% of flocks were juveniles, and indicates that the breeding season of 2009 was a very good one. This was due to the good rainfall in southwest Victoria in winter and spring of 2009.
Next steps in the research project
In December 2011 and January 2012 three more transmitters will be fitted on birds at flocking grounds.
Further data on survival will be collected in 2012 from the transmitters and observations at flocking sites.
In depth analysis of the data collected will be carried out during 2012.
