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AG LIFE Wimmera Machinery Field Days: Rosellas providing insight into climate

INSIGHT: An eastern rosella pictured on the rural outskirts of Horsham. Picture: KELLY LAIRD

INSIGHT: An eastern rosella pictured on the rural outskirts of Horsham. Picture: KELLY LAIRD

One of the great privileges of living on or being able to visit farms in the Wimmera is the opportunity to get up close and personal with Australian wildlife.
From the region’s wide-open plains to the wetlands and mountain country, the Wimmera-Mallee is home to a variety of plants and animals.
Matching the diversity of farming landscapes in the region is the diversity of native birds, ranging from brightly coloured parrots to raptors, waterfowl and the tiny and highly camouflaged species that occasionally dart across roads or between paddock stubble.
The Wimmera – be it farmland, urban or park environments – is home to iconic rosellas, which rate among some of the most beautifully and diversely coloured birds in the world.
It is these birds that have caught the attention of Deakin University researchers, who are suggesting the colour of the species is based on evolutionary process and climate.
It is information that might help in conserving birds and monitoring and understanding implications of climatic change on natural environments.
Anyone with a vague interest in birds would be aware of the difference between the eastern and crimson rosellas in the Wimmera.
These birds vary from a deep crimson red to a pale yellow across south-eastern Australia, but until now scientists were unsure why.
Research published in the Journal of Biogeography shows habitat background and climate are major drivers of the colour variation. 
Paper co-author Dr Mathew Berg, from the Centre for Integrative Ecology in Deakin’s School of Life and Environmental Sciences, said the rosella’s colour variation was extreme for a single species.
“For most birds, and many other animals, when they have orange, yellow or red colouration that is due to carotenoid pigments, which come from food, mostly fruits and vegetables,” he said.
“But parrots have a completely different pigment system – psittacofulvins – found nowhere else in nature.
“They don’t take it in through their diet, instead it’s thought to be produced in their feather follicles.
“While we’ve long known how unique parrot coloration is, we haven’t known what function the colour fulfils or why it varies within or between species. And that’s unusual because parrots are some of the most colourful animals in the world.”
Crimson rosellas are most common around coastal Victoria, New South Wales and south-eastern Queensland.
Yellow rosellas typically inhabit drier areas along the Riverina in Victoria, New South Wales and South Australia.
‘Intermediate’ birds, which come in varying shades of orange, can be found in the Adelaide hills, as well as small pockets of Victoria and NSW.
And then there are parts of the Wimmera, caught in the middle ground between all areas, where there seems to be a mix between crimson and traditional eastern colouration.
The Deakin study is a test of ‘Gloger’s Rule’, a theory on observations that birds tend to be more darkly pigmented in humid habitats.
Dr Berg said it is only due to rapid advances in technology that science was able to look at large sets of data to consider possible factors in combination.
“When we crunched the numbers we found rosellas’ colours seemed to be closely related to the colour of the vegetation of their habitat, links which might arise to help them be more camouflaged from predators or conversely to stand out to other members of the species,” he said.
“Rain and temperature were also important factors. Areas with hot summer temperatures were the best predicator of where to find yellow birds, which could be because the lightest colours afforded the least heat stress, suggesting thermoregulation was also an important factor in coloration.”
While Australia’s crimson rosella populations are abundant, Dr Berg said study findings could have important implications for the conservation of other parrot species, with about a third endangered or threatened by extinction.
“Parrots are one of the most threatened groups of birds in the world, mostly due to habitat destruction, but also due to introduced species and trade for pets,” he said.
“They play a pivotal role in our ecosystem, excavating hollows, pollinating plants and spreading seeds, but they have a big conservation problem.
“Work like this increases our understanding of the habitat requirements of parrots, why they can live in some areas and not others.
“Changes from habitat modification and climate change might affect where parrots are able to occur and where they’ll disappear from.
“This research will help us predict when and where a species decline will happen and why.
“We now hope to model different climate change scenarios and where the parrots might move to. For example, as Australia gets hotter and drier we might see numbers of yellow rosellas expand and replace some of the colour forms in other areas.”

The entire February 27, 2019 edition of The Weekly Advertiser is available online. READ IT HERE!

The entire February 27, 2019 edition of AgLife is available online. READ IT HERE!

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Posted on Feb 27 2019

Posted by on Feb 27 2019. Filed under Agriculture, Environment. You can follow any responses to this entry through the RSS 2.0. You can leave a response or trackback to this entry

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