Interactions between brolgas and sarus cranes in Australia

  • Timothy Donnelly Nevard

    Student thesis: Doctor of Philosophy (PhD) - CDU


    Brolgas and Sarus Cranes use agricultural lands on the Atherton Tablelands in Australia, where they come into conflict with farmers. To help frame their conservation management, this research investigates genetic, spatial, temporal and socioeconomic patterns.

    Work on Brolga genetics (incorporating data from this research) which identifies only small variation between northern and southern populations (exluding New Guinea) has recently been published, so the genetic component of this thesis has focussed on the Australian Sarus Crane. Analyses of 10 microsatellite loci and 49 mitochondrial control sequences have established that it differs significantly from both South and South-east Asian subspecies. A sample from the extinct Philippine subspecies also clustered with the Australian Sarus Crane, hinting at its potential importance in relation to reintroduction to Luzon.

    Early observations of suspected Brolga and Sarus Crane introgression coincided with significantly increased opportunities for interaction when foraging on agricultural crops. Bayesian clustering based on ten microsatellite loci has confirmed that Australian cranes hybridise and that their hybrids are fertile. Genetic analyses have also provided definitive evidence that Brolgas and Sarus cranes migrate between the Gulf Plains and Atherton Tablelands.

    Abundances of both species on the Atherton Tablelands were positively correlated, with Sarus Cranes more abundant on fertile volcanic soils and Brolgas in outlying cropping areas, closer to roost sites. Both occurred at their highest densities on cultivated land, as well as harvested maize and peanut stubbles.

    Farmers were interviewed to explore their current attitudes and future intentions towards cranes. Most are beginning to reduce post-harvest crop residues and move to perennial crops; diminishing traditional crane foraging opportunities and increasing the potential for conflict resulting from crane damage to new plantings. By creating specific foraging areas, crane tourism could provide new feeding opportunities for cranes but as they are mobile and able to take advantage of newly created cropping areas, abandonment of the Atherton Tablelands Key Biodiversity Area is therefore also possible.
    Date of Award2019
    Original languageEnglish
    SupervisorStephen Garnett (Supervisor), George Archibald (Supervisor), Mike Lawes (Supervisor) & Ian Leiper (Supervisor)

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