Wednesday, 21 November 2012

Sensationalist press coverage - is this always the way the general public will see our work?

This is just a quick post today, and features an article in Engineering & Technology magazine which in turn has quoted me.  I was pretty relieved to see that I'd been quoted appropriately and I come across as a voice of caution.  However, the real reason I'm blogging about it now, is because it raises questions about the 'face' we present to the non-specialist audiences when translocations are covered in the media.

E & T magazine has a print circulation of 180,000, mostly professional engineers, and is published online.  If we assume this is the first time many of these readers have heard about assisted migration, it presents quite a controversial picture.  Importantly, careful reading of this article reveals that it is well-balanced in its portrayal of when out-of-range translocations should be used, but how many people read this sort of article carefully?  Instead, will the take home message to many engineers be that biologists can sort it out - we're not there yet but it won't be long before we can move threatened species with certainty.  Is that the message they will read because that's the message they want to see?

Of course, I don't want to polarise engineers and biologists as 'them and us', we're going to have to work closely to make sure ecosystem functioning is protected whilst we continue to develop the infrastructure to house, educate and employ the 7 billion people on the planet.  But how do we communicate a more nuanced message that can actually achieve results?

Pool, R. (2012). Assisted migration and the ethics of playing  'eco god'. Engineering & Technology Magazine, 7(11). Available at:

Sunday, 18 November 2012

Have the guidelines really sunk in?

This post features a paper by Irene Perez and co-authors (2012), and is a wake-up call for those of us undertaking translocations as it reports on the lack of compliance with 10 key criteria for evaluating translocation projects. None of the criteria will be new to anyone who has read the IUCN Guidelines on Re-introductions (1998) and so it is pretty shocking to see that the median number of criteria in published studies is three, and in a dataset of Spanish translocations used to avoid publication bias, the median number of criteria used rises only to five. Even if, as the authors acknowledge is possible, the publications and reports neglect to mention criteria that were addressed in any feasibility assessment of translocations, it seems appropriate to expect that a full rationale of every translocation is available for all stakeholders to view.

Perez et al. go on to propose a propose hierarchical decision-making system, represented as a flow chart.  It is sensible and easy to apply to real examples of candidate species for translocation. However, I worry that with all attempts to provide a framework for complex decision processes, some of the important detail is omitted.  Ultimately, the responsibility of properly interpreting the decision-making system is left with the person undertaking a translocation and this framework might be open to misuse whether intentional or not.  For example, the second level of the decision-making system asks if risks are posed to the target species, other species or ecosystems by undertaking a translocation.  As Perez et al. have demonstrated, risk evaluation is not a strong point in the translocation community and the comprehensiveness of risk assessment will vary enormously based on practitioner capacity and data availability. Further, the dichotomous outcome following the question on risk is presented as 'intolerable risk' versus 'tolerable risk' and this is a subjective decision that I know from experience would divide stakeholders in species conservation.

It seems to me that we need to get better at explicitly addressing guideline documents and particularly the area of evaluating risk potential in terms of the target species and other species and the ecosystem at both the donor and recipient sites. We also need to develop robust ways of judging where the balance lies between tolerable and intolerable risks and involve stakeholders in this decision. There is plenty of treatment of risk in the scientific literature but as far as I'm aware (and Perez et al.'s paper would support me on this), few examples of practical assessments of risk prior to a proposed translocation. If someone out there is already doing this please make yourselves known - we need to learn by your example!

Pérez, I., Anadón, J. D., Díaz, M., Nicola, G. G., Tella, J. L., & Giménez, A. (2012). What is wrong with current translocations? A review and a decision-making proposal. Frontiers in Ecology and the Environment, 10(9), 494–501. doi:10.1890/110175

Thursday, 8 November 2012

Combining data-led methods with expert opinion - how Bayesian approaches can bridge the gap between academia and practice.

With hindsight, I have mistakenly avoided Bayesian approaches to ecological modelling  because they incorporate prior beliefs. The quantitative scientist in me thought that this sounded a little too vague to be of use in conservation and would surely fall foul of bias towards preconceived ideas. However, after reading the paper featured below and the detailed supplementary materials, I am now a convert to Bayesian techniques and hope to incorporate them into my work in the future.

Laws & Kesler (2012) have developed a model for selecting translocation sites for the Guam Micronesian kingfisher (GMK), Todiramphus cinnamominus cinnamominus and to me, it seems like an excellent way of combining quantitative methods with common sense whilst incorporating the complexity of issues involved in selecting suitable sites for translocation. The best way I can explain their approach is to describe their inference diagram: imagine a tree where the main thing we're interested in, island suitability, is the trunk. The trunk splits into four branches representing ecological requirements, impacts on native species, anthropogenic threats and operational support. The tree continues to branch until the generic factors associated with any translocation (e.g. presence of disease, habitat protection laws, food availabilty) give way to GMK-specific factors (e.g. West Nile virus, protected areas, insect prey). At that point, my tree analogy breaks down because some of the 'twigs' feed into several branches but hopefully, you appreciate that this is a relatively straightforward way of representing the complexity in the GMK's translocation needs.

The next job is to assign conditional probablities to each of the factors that contribute to island suitability. For habitat suitability, the two components of available area of suitable vegetation and the extent of habitat fragmentation were modelled using data from 156 Micronesian islands and the occurence of kingfishers of the same genus as GMK. This was used as training data for the GMK model to select candidate translocation sites from 239 island. The rest of the modelling process relied on qualitative decisions to set categorical outcomes, for example, if predatory non-native species were present, the island would be deemed unsuitable. These were then translated into quanitative combinations for the purposes of the judging each island's suitability (see appendix A of the paper for more details).

Only five islands were considered suitable for GMK translocation and even then, they were thought to require varying levels of management. Site visits to the five islands found two of these to be unsuitable due to degraded habitats and lack of political support. The authors caution that the models are only as good as the input data they are built on.

I can see from Laws & Kesler's paper that Bayesian methods have real potential for bridging the gap between expert knowledge and data-driven correlative methods. However, we still need people with the statistical know-how to reach across the gap. Any volunteers?

Laws, R. J., & Kesler, D. C. (2012). A Bayesian network approach for selecting translocation sites for endangered island birds. Biological Conservation, 155, 178–185. doi:10.1016/j.biocon.2012.05.016