Estimating detectability to address alien plant incursions


I’ve contributed a small section to the recently published Detecting and Responding to Alien Plant Incursions. This volume addresses the full continuum of management from pre-border efforts through early detection to selecting management options and overarching governance. It’s a synthesis of the literature that will be of value to researchers. More importantly, it’s framed as guidance to the land managers and policy makers who are responsible for addressing these threats.


The break-out box that Joslin Moore and I were invited to write regards detectability, and how we can go about estimating it experimentally. This process calls on statistics and experimental design, tempered with biosecurity concerns and our desire to accurately simulate real survey conditions. Throughout, we’ve used examples from our hawkweed detection experiments to demonstrate how we’ve made these trade-offs ourselves. We were also able to include a couple of lovely photographs taken by Roger Cousens during our field work.


Hauser C.E. & Moore J.L. (2016) Estimating detectability using search experiments, in Detecting and Responding to Alien Plant Incursions, eds Wilson, J., Panetta, F.D. & Lindgren, C. Cambridge University Press, Cambridge UK, pp 71-75.

Sally, Connor & volunteer teams are a triple threat for hawkweeds


A year ago I posted about the formidable Hawkweed Eradication Program, which is primarily focused on the Alpine National Park of south-eastern Australia. All summer parks staff, private contractors and volunteers scour likely locations to weed out Hieracium species. Detector dogs Sally and Connor are now very much part of the action, too!

Last week we gathered in Falls Creek to evaluate Sally and Connor’s search skills in the Victorian environment. We sent them – plus a team of the High Plains’ proud volunteer searchers – to some specially selected plots where live hawkweeds were known to be hiding. The three search teams found almost all of those known plants, and additionally spotted several undocumented infestations!


It was good news for us, and the program even made the news. (For example, you can check out an article in The Age, an ABC Goulburn Murray audio interview and video.) While Sally’s always ready with a smile for the camera, her human colleagues are quick to tell journalists about all the agencies who make this program possible: this time Australian Alps National Parks, Parks VictoriaVictorian Department of Economic Development, Jobs, Transport & ResourcesNSW Office of Environment & Heritage, and dog trainer Steve Austin. My Australian Research Council and University of Melbourne support is now boosted by freshly-enrolled Monash University PhD student Emma Bennett – this time next year she’ll be leading our survey evaluation and research.


Weed Conference Proceedings online

This year I’ve been involved in many conference proceedings! Following on from a suite of malleefowl studies, here are a few that address hawkweed management in the Alpine National Park.

I missed the 6th Biennial Weeds Conference hosted by the Weed Society of Victoria, but my colleagues Angela Constantine (DEDJTR) and Keith Primrose (Parks Vic) thoroughly covered the range of strategies and operations they have in place for eradicating Hieracium species from Victoria. These include their current method for prioritising locations and allocating search effort across the vast national park (Constantine et al. 2016), which is adapted from research that I led 6 years ago. They’ve also introduced a monitoring and extirpation framework that’s based on Honours research that Keith Primrose pursued with me in 2014 (Primrose et al. 2016).

A few months later I was able to represent Team Hawkweed alongside Angela Constantine, Hillary Cherry and detector dog Sally at the 20th Australasian Weeds Conference. In a single Hawkweed-focused session, Angela gave an encore of her previous presentation (Constantine et al. 2016), and Hillary followed up with an overview of the entire national program (Cherry et al. 2016).

My presentation focused on the design and findings of our detection experiments. We’ve been playing a series of hide-and-seek games in Victoria and NSW in order to understand and compare the strengths and weaknesses of human and canine searchers of hawkweed. My accompanying manuscript (Hauser et al. 2016) focuses on the strategies we use when we design these experiments – it’s intended to offer a bit more detail and insight than we’d typically include in a Methods section. It also includes bonus material on John Weiss’ (DEDJTR, Plant Biosecurity CRC) detection experiments comparing human and UAV-based detection of vineyard disease.

In a grand finale, Sally took the stage to demonstrate her nose for hawkweed. She’s higher entertainment (and cuteness!) value than our science and management activities – thankfully that’s all packed away neatly in this series of proceedings for future reference.


Cherry H., Constantine A., Primrose K., Hauser C. & Tasker K. (2016) It takes a village: detection dogs, partnerships and volunteers aid hawkweed eradication in mainland Australia. In Randall R., Lloyd S & Borger C. (eds) Proceedings of the 20th Australasian Weeds Conference. Weeds Society of Western Australia, September 2016, pp 164-170.

Constantine A., Hauser C.E., Primrose K. & Smith N. (2016) Hawkweed (Hieracium spp.) surveillance: development of a targeted and robust plan for the Victorian Alps. Plant Protection Quarterly 31: 28-32.

Hauser C.E., Weiss J., Guillera-Arroita G., McCarthy M.A., Giljohann K.M. & Moore J.L. (2016) Designing detection experiments: three more case studies. In Randall R., Lloyd S & Borger C. (eds) Proceedings of the 20th Australasian Weeds Conference. Weeds Society of Western Australia, September 2016, pp 171-178.

Primrose, K., Constantine, A., Smith, N. & Pascoe, C. (2016) Eradicating hawkweeds (Hieracium spp.) for the Victorian Alps: improving the efficiency and effectiveness of control whilst mitigating off-target impacts. Plant Protection Quarterly 31: 33-37.

PhD scholarships at Monash University


Dr Joslin Moore is advertising two terrific PhD scholarships at Monash University! I’m co-supervising one of these projects (and Dr Michael McCarthy is co-supervising the other).

Both projects address how we can best search for rare targets in ecological surveys. They’ll involve experimental design, data collection in the remote and ruggedly beautiful Alpine National Park, statistical modelling and conservation decision-making.

Jos’ and my project also rolls in concepts of novel search methods and how we can best integrate them into existing programs. It’s an opportunity to learn from the state government agencies managing a hawkweed eradication program as they investigate the combination of human search teams, trained dogs and unmanned aerial vehicles that will best detect every last hawkweed.

Jos and I have collaborated with hawkweed managers for many years. You can read more on this blog about research we’ve published, fieldwork we’ve done, coverage in other media, and three awards we’ve won.

For more details on the PhD projects and how to apply, visit Joslin Moore’s website. Applications close 17 August 2016.

Science & Innovation Award


I am the delighted recipient of a 2016 Science & Innovation Award for Young People in Fisheries, Forestry & Agriculture in the CSIRO Health & Biosecurity category. Prizes were announced last week in Canberra at ABARES Outlook but I was too occupied by my data collection to attend!

This award will support my ongoing research into the capacity of detection dogs to contribute to hawkweed eradication on mainland Australia. With the help of a research assistant, I’ll be building new time- and distance-based detection models, then taking the models to the International Statistical Ecology Conference in Seattle.

To coincide with the award, I’ve written an article for the University’s Pursuit website.

Categorized as weeds

Sniffing out Kosciuszko’s hawkweeds

NSW OEH dog handler Hillary Cherry takes a search break with detection dog Sally.

I’ve spent the past week in Kosciuszko National Park, contributing to the mammoth team effort eradicating hawkweeds (Hieracium species) from mainland Australia. Dozens of parks staff, state weeds staff, contractors and volunteers train their eyes on rosettes that could otherwise be mistaken for common daisies. Their goal is to find and kill every last one of these interlopers.

The searchers’ newest team-mate Sally prefers to follow her nose. She’s a working dog trained specifically to distinguish hawkweeds’ scent from the other plants occurring in the Alpine National Park. I’ve been helping set up fully- and partially- controlled experiments to evaluate detection dogs’ strengths and weaknesses, and compare them to the skills that human teams have been honing for years.

Last week’s program brought together the NSW National Parks & Wildlife Service, NSW Office of Environment & Heritage, NSW Department of Primary Industries, Victorian Department of Economic Development, Jobs, Transport & Resources, my University of Melbourne representation and a cluster of dedicated volunteers, with cameo appearances from dog trainer Steve Austin and up-and-coming detection dog Connor. We’re making great progress, thanks to our diverse skills and shared goals.

Our cutest colleagues are getting coverage on ABC News. For the rest of us it’s time to map track logs, sort spreadsheets and figure out the best way forward.


My research in #ESA15comic

I am mightily chuffed that #ESA15‘s resident artist Luke O’Loughlin included my hawkweed detection research in his comic series this week. Check out his entire gallery here.

I’ve also written a more thorough run-down of the conference on

Practicable methods for weed delimitation

A comparison of
In November 2011 Kate Giljohann & I recommended that Parks Victoria and the Department of Primary Industries search the places highlighted in map (a) for hawkweed infestations. They made it to the places in map (b) (purple tracks) and only found new infestations (red dots) close to the known population extent.

I’ve got a new article available for view online early! I’m proud to lead a team of researchers and weed managers discussing and demonstrating how we can manage weed delimitation.

‘Delimitation’ is a crucial process during a weed eradication program, whereby the full extent of the invasion is mapped out. There’s really no other way of ensuring that your removal method is successfully targeting every last pesky plant. In 2011 the Hawkweed Eradication Project Control Group were wondering whether they’d nailed it. They’d been sending out search teams for years and had drawn a minimum convex polygon (MCP, dashed line mapped above) around the infestations they’d found. But could there be more hawkweed beyond those boundaries? The worst case scenario was that hawkweeds had actually spread much further south, where the terrain gets so tough that they’d probably have to give up on eradication entirely.

‘Further south’ encompasses a huge area, and the Control Group consulted Kate Giljohann and I to prioritise locations for search. While working on a biosecurity surveillance review for ACERA the previous year, I’d learned that very little research literature directly addresses how we should design delimitation surveys! So Kate and I started afresh, adapting my previous hawkweed survey design to increase the value of hawkweeds detected outside the known population boundary. This process also accounts for hawkweed occurrence (via dispersal and habitat suitability) and detection rates, ensuring that search teams visit places where they’re most likely to find far-reaching hawkweed infestations.

The hawkweed project managers used the shaded map we supplied (a above) to direct their GPS-tracked search teams (b above). The good news is that they found no new hawkweeds in the dreaded southern reaches, just a few extra plants to the north and east of the infestations they already knew about. While this was good evidence that they were close to delimitation, the search teams’ GPS practices were inconsistent – it was hard work for Kate and Michael Rigby to clean up the spatial data, and we had little idea how much time and effort the search teams had put in at each site.

In our new article, my co-authors and I document the process of designing, implementing and evaluating this delimitation survey. I’ve even put together a wishlist for future delimitation work. While minimum convex polygons describe infestations that we know about, probability maps can tell us where else our weed population might be lurking. The maps are ripe for Bayesian updating as we collect new survey data. They can also be aggregated into a delimitation score developed by Mark Burgman, Dane Panetta and colleagues to track progress from survey to survey.

Based on what my co-authors and I achieved in this study, I’m optimistic that these measures can be taken in real eradication programs.


Hauser, C.E., Giljohann, K.M., Rigby, M., Herbert, K., Curran, I., Pascoe, C., Williams, N.S.G., Cousens, R.D. & Moore, J.L. (in press) Practicable methods for delimiting a plant invasion. Diversity & Distributions. DOI: 10.1111/ddi.12388

Estimating detection rates for biosecurity surveillance

IMG_9557_colourBiosecurity Surveillance: Quantitative Approaches is a second new book that I’ve contributed to. It starts with the basic concepts of biosecurity, motivations for surveillance and foundational probability theory, then works up to some very sophisticated approaches for risk mapping and survey design.

IMG_9559_colourIn Chapter 8 Georgia Garrard, Joslin Moore and I discuss methods for estimating detection rates and probabilities. Understanding what you’re missing is an important component of biosecurity surveillance and inference, and we’ve done some field experiments and statistical analyses to find out just that. We lay out our experimental designs and findings for hawkweed detection in the Aussie alps and serrated tussock detection in native grasslands. There are also general tips and tricks for designing such experiments, sample BUGS code, and a quick look at the literature on estimating detection and abundance.


Hauser, C.E., Garrard, G.E. & Moore, J.L. (2015) Estimating detection rates and probabilities, in Biosecurity Surveillance: Quantitative Approaches. Jarrad, F., Low-Choy, S. & Mengersen, K., eds. CABI, Wallingford Oxfordshire UK. pp 151-166.

Weed management across sweeping plains

IMG_9244_colourI’ve made a small contribution to the recently published book, Land of Sweeping Plains. The focus of this edited volume is the restoration and management of the native temperate grasslands of south-eastern Australia. It seeks to be much more than a prescriptive textbook, containing a high density of colour photographs, some poetry and artwork, and a discussion of social context and connection.

IMG_9245_colourThe break-out box I’ve written regards how we can select suitable weed management activities. I’ve drawn from the literature of structured decision making and cost benefit analysis to list the set of factors worth considering and how to combine them to rank alternatives.


Hauser, C.E. (2015) Prioritising weed management alternatives, in Land of Sweeping Plains. Williams, N.S.G., Marshall, A. and Morgan, J.W., eds. CSIRO Publishing, Clayton South VIC Australia.