Drones and AI making a dent in Kakadu's war against weeds

For the traditional owners in Kakadu National Park in the Top End of Australia, magpie geese are used as an indicator of healthy country and a way to monitor the condition of now World Heritage listed wetlands.

But as with much of the rest of the continent, the landscape is spoiled by invasive species that have pushed out native flora and fauna -- in Kakadu's case, one such species is para grass.

Para grass, also known as buffalo grass and scientifically as brachiaria mutica, was introduced to Kakadu in the 1960s, prior to it being a national park, as feed for the buffalo and cattle to graze on. The cattle might be gone, but the buffalo and para grass remain.

"Para grass has proven to be a really aggressive and fast-growing weed, and so it spread throughout the park, and where it moves into these flood plain areas, it completely displaces the native plants and really what you're left with is a one- or two-metre high lawn," current Kakadu board member, leader of the National Environmental Science Program (NEST) Northern Australian Environmental Resources Hub, and professor at the University of Western Australia Dr Micheal Douglas said.

"Effectively, it's a monoculture of this weed, completely devoid of native plants, and that comes at a huge cost to the native plants that would provide nesting sites and feeding sites for these magpie geese, for other ducks and wildlife including turtles."

To fight against para grass, a partnership dubbed Healthy Country was created, which saw the coming together of traditional owners who drive the project, the Commonwealth Scientific and Industrial Research Organisation (CSIRO) and NEST, as well as Parks Australia, and Microsoft.

A 90-hectare trial site was chosen by the traditional owners, and DGI Mavic drones were used at heights of 60 metres to take RGB images of the area, which are ingested into Azure and CustomVisionAI is used to identify para grass and geese, with results outputted into a Power BI dashboard.

Code for the project is available on GitHub.

"We've removed para grass from that area, and the results have been spectacular," Douglas said.

"When we first started doing this project, that area was 100% para grass and we were able to count just 50 magpies. Nine months later, the area is teaming with native plants and we recorded more than 1,800 magpie geese."

Douglas told ZDNet that it's not as though 1,750 geese have suddenly been created, but the trial could have an impact on the wider environment.

"Just the movement around the landscape of magpie geese has consequences," he said.

"Because one of the big stories in Darwin is magpie geese attacking the mangoes ... mango farmers [are] having to get permits to shoot magpie geese because they're coming in and eating mangoes, and I wonder the extent to which magpie geese are doing that because what would have been native valuable areas for magpie geese to feed is now being displaced by para grass.

"They've got no option now, it's not a preferred food, so by creating those areas of favourable habitat again, it's probably going to take pressure off that problem as well."

After spending a decade in the Northern Territory as a ranger, CSIRO research scientist Justin Perry said he has spent his fair share slogging through para grass, killing it, and being "being perpetually frustrated with not actually winning that war".

"Weeds are terrible things to manage, they always come back, they're at such large scales," he said. "Kakadu National Park, it's two million hectares, these wetlands are enormous, some of the biggest wetlands in the world. When you get an invasive weed like para grass, it's not a trivial problem."

Compared to previous biodiversity and land management techniques, where Healthy Country works, according to Perry, is that it provides timely, visual feedback.

"We've gone out and flown the drone, collected some information, it's then been provided back to the rangers the next time we went out there. And so you can look at it, and go 'oh jeez, we actually were successful'," he said.

"And that's been an amazing motivator, because weed management is thankless, it's a thankless task.

"When you're standing at ground level, you're looking out over thousands of hectares of weed, and you stand and go: 'What am I doing? What can I actually achieve here?'"

Due to wanting the processes of Healthy Country adopted by others, Perry said the choice of off-the-shelf DJI Mavic drones was made, and hence the challenge of needing to use only RGB images for processing needed to be overcome.

When doing a pass, the drones fly a pre-programmed transect at a height 60 metres above the ground.

"But the rangers don't have to think about that, they just have to go out there and press the button ... the drone comes up, it flies, it does its route, it comes back in and it lands," Perry said.

"If it runs out of batteries, it comes back and lands, they put a new one in and it goes and flies it again and finishes off the transect."

One scientific benefit of Healthy Country, Perry told ZDNet, was the ability to constantly monitor habitat year round.

"A lot of the work that gets done on things like mobile species, like magpie geese, are correlative because you might get two cracks a year at doing a survey for them. [They're] usually done by a light plane or helicopter and they'll just be counting ... across the thing, so it's a real snapshot and so these more dynamic approaches can then allow us to build more mechanistic models of habitat use and threats," he said.

"I think from a hard science perspective on the ecology of magpie geese, how they're using that wetland, and how they're responding to threat management is going to be a really important science outcome that we will most definitely publish."

For CSIRO principal research scientist Dr Cathy Robinson, the partnership is an example of the "science mob" working well with traditional owners.

"Recent evidence shows that there's 50% of our protected areas across the world is under indigenous owned lands," she said. "80% of the globe's biodiversity is under indigenous owned areas."

"This is huge. So the planet under pressure, our only and our best pathway to achieve these really big challenges -- think weeds, think feral animals, think that the consequences of climate change and our threatened species -- our best pathway is in through partnership with Indigenous people."

While traditionally spraying para grass involved aerial distribution involving a helicopter, or using a combination of a vehicle and backpacked-mounted spraying, Douglas told ZDNet that after the success of the trial, less onerous methods were being examined.

"They're also now bought a steam gun to try and look at getting away from chemicals and using steam, but you can't do that at the scale initially that this problem occurs at," he said.

"It's also meant that they're now thinking about well can we get drones to actually do the spraying rather than having to do that dangerous process."

Healthy Country is partially funded from Microsoft's $50 million AI for Earth program launched in 2017 to provide grants to solve environmental challenges with technology.

Microsoft Australia managing director Steven Worrall said the company has awarded 484 grants, of which Australia has 12.

In April, Microsoft announced six Australian recipients including Monash University, Griffith University, Queensland University of Technology (QUT), InFarm, the Australian Wildlife Conservancy, and Bush Heritage Australia.

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