DUCKS, DRONES AND DATA: a new approach to season setting
Associate Professor Graham Hall was out in the field again during the 2016 opening weekend, collecting head and wing samples. it is a fraction of the work being undertaken on Australian waterfowl with the aim of implementing a scientific based adaptive ma
When news of the sudden decision to close Lake Elizabeth because of the presence of about 155 threatened blue-billed ducks came through, Associate Professor Graham Hall was standing on the shoreline surveying the waterfowl.
On the eve of the season opening, hunters were already in the water preparing hides and setting decoys.
Within an hour they would be informed by authorities they had to leave.
Professor Hall had to leave too, and find a new location to collect head and wing samples from hunters. The next morning he was set up along Gunbower Creek near Koondrook. “It's been a challenging weekend; the issues around closures and so on has probably meant we are down a few samples but overall it has gone well,” he said after two days of collecting samples. “The hunters are certainly much more receptive to the program now than when we started, which was in 2009. “When I finally do the numbers on it we will have notched up more than 3000 samples over those eight years.”
The samples are used in conjunction with meat ant samples from across Australia. A stable isotope signature present in the duck samples and the ants provides evidence of the movement of birds.
The wing measurements can also be used to produce age data once baseline comparison measurements from knownage ducks are established. “We started the program because up until then we might have had a number of ducks taken in Victoria every year but we didn't really know anything about that number, so the whole program was designed around trying to get some biological knowledge of the birds that made up that number,” Professor Hall said. “We didn't know anything about the numbers of each individual species that got taken, we didn't know what sex ratios got taken and really, where we want to end up, is that we have got all this information on unknown-age ducks and we would like to put that together with a program on known-age ducks so that we can say, right, a wing length of X in an unknown age duck translates to an age of X based on a study of known age ducks.”
While the sudden closure of Lake Elizabeth to protect a threatened species disrupted Professor Hall's plans, he's more concerned about what he says is a “haphazard” and unscientific approach to season setting in Victoria.
He takes issue with the Eastern Australian Waterfowl Count and the key role it plays in season determinations. “The whole issue about harvest of anything, whether it is butterflies or elephants, is that is has to be scientifically evidence based and we really don't have that for Australian game birds,” he said. “We have a number, and a number is just a number; it is not telling you anything else. If you are going to have evidence-based programs you have got to know a lot more than just a number.”
Professor Hall unpicks the Eastern Australian Waterfowl Count in this way: it started in 1983 and was designed to count Wood ducks in a small area of New South Wales. The methodology outlined in the original Commonwealth Scientific and Industrial Research Organisation (CSIRO) technical bulletins was never designed to be used to conduct surveys from the Gulf of Carpentaria to Bass Strait. “They were also never designed to count all of the waterfowl species; they were never designed to count broods of ducklings and all this sort of stuff,” Professor Hall said.
“There is a lot of scientific concern about that methodology and yet it is really the only piece of information used by the various states. They say they use the Southern Oscillation Index and all these other things but there is no correlation ever talked about between all of those bits of information.
“It is really a lick the finger and stick it out the window and say, ‘yeah that seems 'bout right, we'll do this'.”
Professor Hall calls it “survey by rote”: flying lines every two degrees of latitude going from north to south even if that means missing significant waterfowl habitat.
One benefit of an arid landscape is that it is well known where water is and Professor Hall has been part of a team investigating a better model that regularly surveys and counts specific wetlands, providing not only accurate count data but trends over time. “We've been working in NSW for the past 18 months or so looking at using drones to count waterfowl and that is a much more rigorous and scientifically reproducible way of doing it. We're taking photos on these wetlands so if I say there are 100 ducks there and someone else says there are only 10, we can actually dig out the frames,” he said. “With the Eastern Australian Waterfowl Count all we are presented with is a report each year that says there are a certain number of ducks on that transect line.”
The drone data is combined with new computer software that uses satellites to show the location and quantity of water. “It tells us how much free water, how much edge and how much dry land is around that edge,” he said. “We can work all that into a sensible, accurate index of abundance of waterfowl, and that is the other issue with the Eastern Australian Waterfowl Count: they will give you an absolute number and we really don't need an absolute number. We need to know whether the populations are changing, going up or down and whether they are changing in their distribution; an absolute number is pretty meaningless.”
Professor Hall cites a review of Field & Game Australia's annual on-ground waterfowl counts that concluded that some years are better than others, some regions are better or worse than others and that within those regions, some wetlands are better or worse.
>> “The question then becomes why some wetlands are good and some aren't,” Professor Hall said. “There wasn't time to answer that in the study but it shows us that instead of counting hundreds of wetlands, which in an ideal world we would do but we're all time poor, let's focus on where we can get the biggest bang for the buck. “There are certain wetlands that could be surveyed each year, which would give us that relative number of how waterfowl are going up or going down. “By then plugging in the new software showing where the water is and whether it is going up or down and tying it all together rather than relying on one single piece of information, we can start to say, for example, that Gippsland has huge numbers of waterfowl on lots of areas, the north-west of the state has large concentrations but on smaller numbers of wetlands and we can start to proportion the harvest.”
In a paper on adaptive management Professor Hall highlighted the current gaps in knowledge concerning the relationships between duck population density throughout the landscape in space and time, and the ability of hunted populations to recover to pre-hunted levels.
He concluded that long-term monitoring was required in the relationship between habitat, density and hunting.
A new research paper published a few weeks ago detailing the unmanned drone trial in NSW provides the platform for a shift to targeted monitoring of key waterfowl habitat.
The team, which included Professor Hall, found a fixed-wing drone could be flown as low as 60 m above the water level without disturbing waterfowl and multi-rotor models could get as low as 40 m.
Using flight paths that did not cause disturbance, commercially available on-board cameras were able to capture images of sufficient quality to identify waterfowl and even much smaller birds such as swallows. “Our results show that with proper planning of take-off and landing sites, flight paths and careful UAV (unmanned aerial vehicle) model selection, UAVS can provide an excellent tool for accurately surveying wild waterfowl populations and provide archival data with fewer logistical issues than traditional methods such as manned aerial surveys,” the researchers concluded.
The drone counts, satellite data on water availability and the evidence from ongoing research on harvested birds can build a much bigger and clearer picture for management authorities. “It gets you into a modern paradigm of management that is done all around the world called adaptive management,” Professor Hall said. “You are collecting information on the previous season and you are making decisions based on that and additional science and adapting your management for the next season. “That is being done all over the world, except for Victoria it seems.”
Graham Hall wants to see targeted monitoring of key wetlands like Johnson Swamp using unmanned drones and satellites to build a more complete picture
Graham Hall recording head and wind data from samples collected from hunters along the Gunbower Creek during the opening weekend of the 2016 season