Thursday, 6 December 2012

1 million fish reveal translocation and captive-breeding synergies

The translocation described in this post could be an example of assisted migration although not in the sense that this is a climate change-motivated intervention. The movement of the Chinook salmon described by Holsman et al (2012) is assisting migration by transporting fish passed hydroelectric dams from the spawning headwaters to the ocean. As someone who has worked with threatened species and the small numbers of individuals this normally entails, I am envious of their sample size - over 1 million tagged fish made up the dataset and allowed an exceptional number of explanatory variables and interactions to be explored.

Key to their findings are the fact that their million fish represented wild and captively reared individuals, and translocated fish (moved down river) and non-translocated fish (in-river migrants) in all combinations over the period 1998 - 2006. They found that the origin of the fish and whether they were translocated around the hydropower schemes interacted synergistically on fish mortality: captive-reared fish benefited from being transported while wild fish were detrimentally affected by translocation. The latter occurred despite the fact that transportation should minimise deaths associated with migrating through hydropower systems.

The authors go on to explore a range of factors affecting survival in the marine environment before concluding with three important recommendations for management. Firstly, that the effects of management and environment can interact and this must be considered at the outset of any conservation programme. Secondly, that the survival translocated or captive-bred populations cannot be predicted from survival of wild populations because the intervention can alter some of the key phenological, behavioural, genetic and demographic parameters of a cohort. Thirdly, and I feel most importantly, practitioners should adopt an adaptive management approach. Whilst Holsman et al (2012) have the benefit of 1 million fish in their dataset, all translocation projects can improve the ability to identify and respond to unexpected and detrimental outcomes if translocated plants and animals are followed throughout the translocation programme on an individual basis.  As a systematic reviewer of plant reintroductions, I can vouch for this recommendation - survival analysis of an entire cohort is much more diagnostically powerful than samples of an already small population. However, I know it is easier said than done if you are say, trying to reintroduce a plant using seed, but it's not impossible and the rewards for the success of the project are more than worth it.

Holsman, K. K., Scheuerell, M. D., Buhle, E., & Emmett, R. (2012). Interacting Effects of Translocation, Artificial Propagation, and Environmental Conditions on the Marine Survival of Chinook Salmon from the Columbia River, Washington, U.S.A. Conservation biology : the journal of the Society for Conservation Biology, 26(5), 912–922. doi:10.1111/j.1523-1739.2012.01895.x

Saturday, 1 December 2012

Definitions of conservation translocation

This post is just to highlight the fact that I've updated the 'definitions' page on this blog (see top tabs to find the different pages).  Definitions are key to a discipline such as this one, where confusion in terminology generates a host of uncertainties about the motivations, appropriate methods and policy implications for species conservation.  For this reason, the IUCN Task Force charged with revising and expanding the Guidelines for Reintroductions and Other Conservation Translocations spent a great deal of time scrutinising the definitions and testing their applicability under a range of scenarios and case-studies.

The new definitions for conservation translocations include a shift from 'historic range' to 'indigenous range' and the following interventions:
  • Population Restoration - including reinforcement and reintroduction
  • Conservation Introduction - including assisted colonisation and ecological replacement

The full Guidelines are available in an interim version just now (please email me if you would like this version) but will be freely available on the IUCN Re-introductions Specialist Group website in the final format soon.  There are also plans underway for translation of the Guidelines into several languages and hard-copies to be made available.

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

Thursday, 4 October 2012

Is host tolerance to pathogens and herbivores is more beneficial than resistance in reintroduced populations?

In just about every set of reintroduction guidelines I’ve ever read, one of the primary recommendations is always to eradicate the threats that caused the extirpation of populations of the target species. However, dealing with threats that have an extensive impact are often impossible to eradicate or limit to a specific location.  In the paper summarised below, Matthew Venesky and his co-authors (Venesky et al. 2012) examine several lines of evidence to look at the incidence of pathogens and herbivores and how reintroductions can be optimised to cope with a threat that can’t easily be controlled.

The paper relies on three concepts to make their argument that particular traits are key to successful translocation of species threatened by non-native pathogens or herbivores: virulence, tolerance and resistance. Virulence is defined "as the per capita effects of a pathogen or herbivore". Host tolerance is expressed as the ability to withstand an attack with little loss of fitness. Resistance refers to the reduction of pathogen or herbivore impact through deterring infection or herbivory, or attacking the pests directly. Tolerance is thought to have a neutral or positive consequence for pest abundance whereas resistance has a negative impact on pathogen or herbivore abundance.

The main thesis is that the generation time of pathogens and herbivores (especially invertebrates) is shorter than that of their hosts and can therefore be subject to selection pressures that are exerted as a result of the negative influence of host resistance. This creates pest populations that evolve countermeasures against resistance mechanisms; the lag in the host response means that reintroduced populations suffer high mortality before developing adequate resistance. Hosts which exhibit tolerance rather than resistance do not place strong selection pressures causing increased virulence, and in some cases may even select for decreased impacts. As a result, captive breeding that selects for tolerant (rather than resistant) individuals for translocation, may maximise the chance that a reintroduction attempt will survive long enough to produce progeny.

The two case studies use examples of non-native organisms to explore how captive breeding might select for tolerance rather than resistance to cope with pathogens and herbivory. The first is the fungal pathogen Batrachochytrium dendrobatidis (Bd) that causes chytridiomycosis and has decimated amphibian populations across the world. Selection for resistance involves several suggested approaches including identifying indicators of infection but minimal loss in fitness.  The second example is the cactus moth (Cactoblastis cactorum) which was succesfully introduced to Australia to reduce the prevalence of non-native prickly pear (Opuntia spp.). Unfortunately, the cactus moth has exhibited similar voracity against two narrow endemic species of cactus in Florida. Selection for tolerant genotypes might involve identifying individuals that drop pads from the main plant when stressed by moth herbivory.

The final section of the paper adds some important caveats to the discussion that shifts in host tolerance may have unexpected consequences such as a trade-off for competitive abilities of the host and the existence of low levels of pathogens and herbivores that could act as a reservoir for invading non-tolerant communities. As a result, Venesky et al. (2012) recommend adaptive managment strategies and using an experimental approach to compare the survival of resistant and tolerant genotypes post translocation.

Venesky, M. D., Mendelson III, J. R., Sears, B. F., Stiling, P., & Rohr, J. R. (2012). Selecting for Tolerance against Pathogens and Herbivores to Enhance Success of Reintroduction and Translocation. Conservation biology, 26(4), 586–592. doi:10.1111/j.1523-1739.2012.01854.x

Wednesday, 26 September 2012

Decision tools for reintroduction but who actually uses them?

My post today was going to be a summary of a paper by Adam Schapaugh and Andrew Tyre of the University of Nebraska-Lincoln on Markov decision processes (MDPs). These enable conservation decision-making by dictating what action should be taken based on the state a system is in, and incorporates a reward for having taken the action. Schapaugh and Tyre have used as one of their examples, an hypothetical reintroduction to demonstrate this. MDPs require the user to describe the state variables, set what actions are associated with all the combinations of state variables, and construct a reward system that means the actions can be optimised to create the best outcome. In the paper this means that a set of state variables (e.g. source population size) affect which actions (e.g. capture and release) are undertaken to produce a target population of a given size through reintroduction.

Schapaugh and Tyre present a way of selecting the most relevant variables to include in order to make the best informed choices using MDPs. Their algorithm chooses the actions that maximises rewards where the rewards are set by the user to match their targets (e.g. creating a population of the target species). The actions which reap largest rewards are selected first; the actions which provide negligible or no reward are removed from the process. There is obvious application to species recovery programmes as a decision tool for when and how to act and this paper seems to present an approach for streamlining this potentially complex process.

I wish I was in a position to comment on the utility of their approach and critique it in a way that would be useful to conservation translocations. However, I am new to MDPs and instead would like to pose the question: who uses MDPs in the real world? This then leads me to ask: how do they (the practitioners) make the jump from algorithms in a paper to policy and implementation? And finally, how long does it take for advances such as the one presented in this paper to be absorbed into practice?

Feel free to comment - the questions above are not rhetorical and are a genuine attempt to understand the use of MDPs in relation to translocations.

Schapaugh, A. W., & Tyre, A. J. (2012). A simple method for dealing with large state spaces. Methods in Ecology and Evolution. doi:10.1111/j.2041-210X.2012.00242.x

Monday, 17 September 2012

Translocation implications for the song repertoire of the kōkako

The North Island Kōkako, Callaeas cinerea, use song in year-round territory defence and strengthening monogamous pair bonds.  Sandra Valderrama and co-workers described song repertoire in six natural populations, and two translocated populations on New Zealand's North Island to describe how population size affected this important behaviour.

They found that pairs in smaller populations have lower song diversity and higher shared song phrases than larger populations.  In many cases translocated populations are very small relative to the size of natural populations and this study was no exception – the two translocated populations consisted of only 18 and 20 individuals. Higher numbers of founding members may be helpful in accelerating population growth through more efficient pair formation and territory establishment and defence.

Their findings also have implications for selecting individuals from natural populations for translocation.  Translocations using individuals from multiple donor populations may result in individuals from smaller populations being at a disadvantage due to a smaller song repertoire and therefore, reduced ability to find mates. This may have knock-on effects for the genetic mixing of individuals from different donor populations – if the birds from smaller populations cannot find a mate due to a lack of the right ‘vocabulary’, their genes will not be represented in the newly created population.

Valderrama, S. V., Molles, L. E., & Waas, J. R. (2012). Effects of Population Size on Singing Behavior of a Rare Duetting Songbird. Conservation Biology, no–no. doi:10.1111/j.1523-1739.2012.01917.x

Saturday, 15 September 2012

First ever 'Reintroduction Biologist' - heralding a new era for the sub-discipline?

Today I read an article on the Chicago Tribune website that named a member of staff at Lincoln Park Zoo as the first ever person to have 'reintroduction biologist' as their job title (  Given that Phil Seddon, Doug Armstrong and Richard Maloney wrote "there is therefore now a recognizable field of reintroduction biology" only five years ago (Seddon et al. 2007), this represents quite a development and a milestone the translocation community should be aware of.

Hopefully we'll see more people join Allison Sacerdote, the Lincoln Park Zoo employee, as the profession develops.  Perhaps more importantly, we'll see increasing numbers of employees of zoos, botanic gardens and statutory agencies who adopt an 'experimental' approach called for by Seddon et al. (2007) and adopted by Sacerdote. In the featured reintroduction project, she will be comparing 'hard' and 'soft' release techniques in order to develop effective protocols for smooth green snakes in Illinois.

Seddon, P. J., Armstrong, D. P., & Maloney, R. F. (2007). Developing the science of reintroduction biology. Conservation biology : the journal of the Society for Conservation Biology, 21(2), 303–12. doi:10.1111/j.1523-1739.2006.00627.x

An introduction of the non-conservation kind

My name is Sarah Dalrymple and I'm a conservation ecologist working in Northern England, UK.  I have a background in plant ecology and after attempting a reintroduction of small cow-wheat (Melampyrum sylvaticum) I became interested in conservation translocations and whether they really could be a viable tool for reversing the decline of threatened species.

I have recently been part of the International Union for the Conservation of Nature (IUCN) Task Force charged with revising their Guidelines for Reintroduction and Other Conservation Translocations.  The membership reflected the double edge of deliberate movements of plants and animals being drawn from both the IUCN Re-introductions Specialist Group and the Invasive Species Specialist Group.

My current research is trying to identify examples of translocations both within and beyond a species' indigenous range in order to assess the effectiveness of interventions such as assisted colonisation when compared to within-range translocations such as reintroduction.  (If I've already confused you with the terminology, please see the definitions page.) I am building a database of conservation translocations and offering to assess the habitat suitability of translocations for practitioners who are willing to share their data - please see the project page for more details.

Finally, if you would like me to blog about any aspect of your translocation work, feel free to contact me:

Looking forward to working with you,