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.

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.

Malleefowl Forum Proceedings now online


In September 2014, the Malleefowl Adaptive Management team visited Dubbo to participate in the National Malleefowl Forum. Recently the Forum Proceedings have been published online, so you can access information on every presentation and poster contributed.

Our team was given a full session to present all the research driving the Adaptive Management project. In the first paper, I provided an overview of how we are applying adaptive management principles to Malleefowl conservation through a nested set of scientific studies.

Mike Bode followed up with an introduction to the qualitative ecosystem modelling that we’re using to collate data and expert opinion. It helps to prioritise threats to Malleefowl persistence and conservation actions that show promise for addressing those threats.

José Lahoz-Monfort developed an experimental design and power analysis that we can use to monitor one particular threat-action pair drawn from Bode’s options: baiting to reduce fox predation. His approach relies primarily on the monitoring data already being collected nation-wide and stored on a national database.

Finally, our recently graduated Master student Rosanna van Hespen, then just starting out on her degree, discussed the potential for motion-triggered cameras to supplement the existing monitoring data and Lahoz-Monfort’s analysis by observing changes in fox activity.

Our work has progressed substantially in the almost-2 years since we made these presentations and we’re keen to release updates into the peer-reviewed research literature very soon! Get in touch if any facets of this project spark your interest.



Hauser C.E., Bode M., Rumpff L., Lahoz-Monfort J.J., Benshemesh J., Burnard T., van Hespen R. & Wintle B. (2016) Applying adaptive management principles to Malleefowl conservation. Proceedings of the 5th National Malleefowl Forum pp 210-215.

Bode M., Rumpff L., Benshemesh J., Burnard T., Lahoz-Monfort J., van Hespen R., Hauser C. & Wintle B. (2016) Predicting Malleefowl dynamics using decision theory and qualitative ecosystem modelling. Proceedings of the 5th National Malleefowl Forum pp 223-236.

Lahoz-Monfort J.J. & Hauser C.E. (2016) Analysing the effects of ongoing and historical fox control on Malleefowl population viability. Proceedings of the 5th National Malleefowl Forum pp 216-220.

van Hespen R., Hauser C.E., Lahoz-Monfort J.J. & Rumpff L. (2016) Camera trap analysis of mallee wildlife. Proceedings of the 5th National Malleefowl Forum pp 221-222.


Adaptive management of a mainland-island metapopulation

The Bay Checkerspot butterfly. Image by USFWS, used under Creative Commons License.

Earlier this year, Ecological Applications published one of QAEcologist Darren Southwell‘s PhD thesis chapters as an article. In it, Darren builds a model of a threatened species following mainland-island metapopulation dynamics and investigates the relative merits of adding new habitat patches, extending the area of existing patches and leaving the metapopulation alone.

It’s clear pretty early on that the best approach for population persistence depends on the colonisation rate. If the species colonises new habitat patches well, then creating new patches is worthwhile because we can trust individuals to find their way over and establish a new subpopulation. If the species disperses to new patches rarely, we may be better off expanding existing habitat patches to secure these local populations.

But what if we don’t know the species’ colonisation rate? Darren goes on to build an optimisation that allows for uncertainty in this important parameter. Even better, it factors in the potential learning opportunities that pop up when we monitor colonisation into empty habitat patches.  This is adaptive management in its most quantitative form.

Darren’s use of stochastic dynamic programming and beta-binomial updating make this a great methodological companion piece to Mick McCarthy’s article on adaptive vegetation management, my PhD research on harvest management and Tracy Rout’s Honours research on threatened species translocation. It’s an elegant approach that prevents the range of learning possibilities from spiralling beyond computational bounds. (Nevertheless, the types and sizes of problems that can be addressed are quite limited.) As a co-author, I most enjoyed diving into this technical detail with Darren.

For those less excited about recursive equations, there’s a nice case study based on a Bay Checkerspot butterfly metapopulation.


Southwell D.M., Hauser C.E. & McCarthy M.A. (2016) Learning about colonization when managing metapopulations under an adaptive management framework. Ecological Applications 26: 279-294. doi: 10.1890/14-2430

Who detects pests in the grains industry?

Source: CSIRO, used with permission.

I’ve devoted a lot of my research effort towards designing active surveillance for biosecurity; that is, the structured surveys that we use to detect specific problem species (like this). Yet many pests are detected incidentally; the Hawkweed Eradication Program can thank a well-trained off-duty volunteer for reporting the third invading species, and their monitoring staff have a detected a number of new Hawkweed infestations as they go about their routine activities. Such reports form a secondary layer of passive or general surveillance. These detections can be pivotal for pest management programs, but they’re much more difficult to quantify and control. What style of training will inform and motivate staff to report pests? What kinds of public awareness campaigns lead to new findings and better management?

During her PhD studies, Nichole Hammond took on this issue in the context of Western Australia’s grains industry. She surveyed growers, agricultural consultants, Department of Agriculture and Food staff, and a self-described cowboy to test their familiarity with the signs and symptoms of four high-priority grain pests. In the second part of her study Nichole went on to assess participants’ likelihood of reporting what they observed and to whom they’d report. This enabled Nichole to analyse the sensitivity of general surveillance; that is, the probability that any existing pest would be detected, reported and therefore managed during routine industry activities. That’s important information for assessing current industry biosecurity practice and identifying where improvement is needed.

This month the survey findings are published in two Crop Protection papers, of which I’m a co-author. Please email me if you’d like a copy of either of them!


Hammond, N.E.B., Hardie, D., Hauser, C.E. & Reid, S. (2016) Can general surveillance detect high priority pests in the Western Australian grains industry? Crop Protection 79: 8-14. doi:10.1016/j.cropro.2015.10.004

Hammond, N.E.B., Hardie, D., Hauser, C.E. & Reid, S. (2016) How would high priority pests be reported in the Western Australian grains industry? Crop Protection 79:26-33. doi:10.1016/j.cropro.2015.10.005

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

Woodland bird classification and its consequences

Is the striated pardelote
Is the Striated Pardalote a woodland bird? Experts are divided! Image by Grahame Bowland, used under Creative Commons License.

I’m proud to share the first publication of PhD student Hannah Fraser, who I co-supervise. During her Masters work, Hannah noticed inconsistencies in the ways that different studies identified Australian woodland birds and she wanted to dig deeper. She really has! In this work, she summarises the literature on nomenclature, measures the inconsistency in Australian woodland bird classification in the research literature, polls study authors on their choices, and demonstrates the quantitative effects of this inconsistency. SPOILER ALERT: there are consequences for conservation. So let’s be transparent, if not consistent.

Head over to Hannah Fraser’s blog for a more detailed summary of the article. The full article is open access so you’re free to geek out over it too!


Fraser, H., Garrard, G.E., Rumpff, L., Hauser, C.E. & McCarthy, M.A. (2015) Consequences of inconsistently classifying woodland birds. Frontiers in Ecology & Evolution 3:83. doi: 10.3389/fevo.2015.00083