Grassland changes put endangered parrot at greater risk
The endangered golden-shouldered parrot, a technicolour species native to Far North Queensland鈥檚 Cape York Peninsula, is abandoning areas of grassland it usually nests in because woody plants are encroaching upon its preferred vegetation.
Credit: Peter Valentine.
Dr Gabriel Crowley, from the University of 糖心vlog官网, assessed the fate of 555 golden-shouldered parrot eggs from 108 nests monitored on Artemis Station by its owner, Susan Shephard, and Charles Darwin University researcher, Professor Stephen Garnett.
They discovered that the spread of woody plants increased the probability of predation, and reduced nest success and survival of nesting adults.
鈥淭he golden-shouldered parrot prefers to nest in areas of low woody-vegetation density, mainly along grassy drainage depressions,鈥 says Dr Crowley, whose research was published in the journal .
鈥淲e observed that they abandoned areas where woody plant encroachment was most advanced, which means it should be considered as a potential threatening process and managed accordingly.鈥
Grasslands are the world's most threatened terrestrial ecosystem, with vast areas disappearing because of the spread of urban and industrial development.
Maintaining remnant grasslands in good condition is therefore essential for the conservation of grassland-dependent species, such as the golden-shouldered parrot.
鈥淚n our study, nest success decreased as the density of trees around the nest increased,鈥 says Dr Crowley.
鈥淢ost losses could be attributed to predation, with the numbers of both adults and chicks taken increasing with tree density.
鈥淭his effect was most pronounced for butcherbirds, which perch in nearby trees waiting for the birds to emerge from the nest. The parrots are therefore most likely to fledge successfully in open grasslands, where they are safe from woodland predators.鈥
Three phases of golden-shouldered parrot habitat loss. A few scattered trees establish around nesting mound (left); tea-tree suckers emerge from grass layer (centre); dense thickets of tea trees shade out termite mounds (right). Credit: Gabriel Crowley.
Dr Crowley鈥檚 three decades of research has shown that the grasslands of Cape York Peninsula have been disappearing under woody plants since cattle grazing replaced management by First Nations Peoples.
鈥淥n Cape York Peninsula, grazing has reduced fuel loads and the frequency of fires needed to keep woody plant encroachment at bay,鈥 Dr Crowley says.
While this study focused on the plight of the Cape York Peninsula鈥檚 golden-shouldered parrot, Dr Crowley says it is indicative of a problem seen around the world.
鈥淪imilar processes may explain the decline of grassland birds across the globe, including from African savannas and North American prairies,鈥 says Dr Crowley.
鈥淕rassland loss is also an issue in South Australia, where urban and industrial development, grazing and rabbits are the main threats. However, fire management is also an essential tool for maintaining the open structure of these systems.
鈥淚t is therefore important that we recognise that while uncontrolled wildfires can have a devastating effect on the environment, when used properly, fire has an important role in maintaining the health of many ecosystems.鈥
NOTE: For more on this research, see Dr Crowley鈥檚 .
Media contact:
Dr Gabriel Crowley, School of Social Sciences, University of 糖心vlog官网. Phone: +61 0438 531 120 Email: gay.crowley@adelaide.edu.au
Johnny von Einem, Senior Media Officer, University of 糖心vlog官网. Phone: +61 0481 688 436, Email: johnny.voneinem@adelaide.edu.au