Tag Archives: pest management

On Culling Overabundant Wildlife

Ecologists have written much about the culling of wildlife from an ecological and conservation perspective (Caughley 1981, Jewell et al. 1981, Bradford and Hobbs 2008, Hampton and Forsyth 2016). The recommendations for culling as a method for reducing overabundant wildlife populations are typically scientifically well established and sensitive to animal welfare. The populations chosen for culling are classified as ‘overabundant’. But overabundant is a human-defined concept, and thus requires some form of social license to agree about what species, in which conditions, should be classified as ‘overabundant’. The problem of overabundance usually arises when humans make changes that permit a species to become so numerous locally that it is having an adverse effect on its food supply, its competitors, or the integrity of the ecosystem it occupies. Once overabundance is recognized, the management issue is to determine which methods should be used to reduce abundance to a suitable level. Culling is only one option for removing wildlife, and animals may be captured and moved elsewhere if that is possible or sterilized to prevent reproduction and further increase (Liu et al. 2012, Massei and Cowan 2014).

All these policy issues are subject to open public debate and these debates are often heated because of different belief systems. Animal rights advocates may push the assumption that we humans have no rights to kill any wildlife at all. News media often concentrate on the most stringent views on controlling populations that are overabundant, and public discussion becomes impossible. Two aspects need to be noted that are often lost in any discussion. First is the cost of alternatives in dollars and cents. As an example, most ecologists would agree that wild horses are overabundant on open range in western United States (Davies et al. 2014, Rutberg et al. 2017) but the question is what to do about this. Costs to reduce horse populations by capturing horses and penning them and feeding them are astronomical (the current situation in western USA, estimated at $25,000 per animal) but this method of control could be done if society wishes to spend money to achieve this goal. Culling would be much cheaper, but the killing of large animals is anathema to many people who speak loudly to politicians. Fertility control methods are improving with time and may be more acceptable socially, but costs are high and results in population reduction can be slow in coming (Hobbs and Hinds 2018). Models are essential to sort out many of these issues, whether it be the projected costs of various options (including doing nothing), the expected population trajectory, or the consequences for other species in the ecosystem.

The bottom line is that if overabundant wildlife populations are not reduced by some means, the result must be death by starvation or disease coupled with extensive damage to other species in these ecosystems. This type of “Plan B” is the second aspect not often considered in discussions of policies on overabundant species. In the present political scene in North America opposition to culling overabundant wildlife is strong, coherent discussion is rarely possible, and Plan B problems are rarely heard. Most overabundant wildlife result from human actions in changing the vegetation, introducing new species, and reducing and fragmenting wildlife habitats. Wishing the problems will go away without doing anything is not a feasible course of action.

These kinds of problems in wildlife management are soluble in an objective manner with careful planning of research and management actions (Hone et al. 2017). Ecologists have a moral duty to present all scientific sides of the management of overabundant species, and to bring evidence into the resulting social and political discussions of management issues. It is not an easy job.

Bradford, J.B., and N.T. Hobbs. 2008. Regulating overabundant ungulate populations: An example for elk in Rocky Mountain National Park, Colorado. Journal of Environmental Management 86:520-528. doi: 10.1016/j.jenvman.2006.12.005

Caughley, G. 1981. Overpopulation. Pages 7-19 in P.A. Jewell S. Holt, and D. Hart, editors. Problems in Management of Locally Abundant Wild Mammals. Academic Press, New York. ISBN: 978-0-12-385280-9

Davies, K. W., Collins, G. & Boyd, C. S. (2014) Effects of feral free-roaming horses on semi-arid rangeland ecosystems: an example from the sagebrush steppe. Ecosphere, 5, 127. doi: 10.1890/ES14-00171.1

Hampton, J. O., and D. M. Forsyth. 2016. An assessment of animal welfare for the culling of peri-urban kangaroos. Wildlife Research 43:261-266. doi: 10.1071/WR16023

Hobbs, R.J. and Hinds, L.A. (2018). Could current fertility control methods be effective for landscape-scale management of populations of wild horses (Equus caballus) in Australia? Wildlife Research 45, 195-207. doi: 10.1071/WR17136.

Hone, J., Drake, V.A. & Krebs, C.J. (2017) The effort–outcomes relationship in applied ecology: Evaluation and implications BioScience, 67, 845-852. doi: 10.1093/biosci/bix091

Jewell, P. A., Holt, S. & Hart, D. (1982) Problems in Management of Locally Abundant Wild Mammals. Academic Press, New York. 360 pp. ISBN: 978-0-12-385280-9

Liu, M., Qu, J., Yang, M., Wang, Z., Wang, Y., Zhang, Y. & Zhang, Z. (2012) Effects of quinestrol and levonorgestrel on populations of plateau pikas, Ochotona curzoniae, in the Qinghai-Tibetan Plateau. Pest Management Science, 68, 592-601. doi: 10.1002/ps.2302

Massei, G. & Cowan, D. (2014) Fertility control to mitigate human–wildlife conflicts: a review. Wildlife Research, 41, 1-21. doi: 10.1071/WR13141

Rutberg, A., Grams, K., Turner, J.W. & Hopkins, H. (2017) Contraceptive efficacy of priming and boosting doses of controlled-release PZP in wild horses. Wildlife Research, 44, 174-181. doi: 10.1071/WR16123

Predator Free New Zealand

The New Zealand Government announced in July 2016 the adoption of Predator Free New Zealand 2050, a program for the control and eradication of introduced pests. It is setting up a new public-private partnership company by the beginning of 2017 to help fund regional large-scale predator eradication programs with the anticipated funding ratio of 1 government dollar to 2 private dollars. This is a bold new program grounded in the fundamental research of an excellent array of conservation biologists that have carried out the field research underpinning what needs to be done to protect native biodiversity in New Zealand.

Because of its isolation and the complete absence of endemic terrestrial vertebrate predators, New Zealand has become a basket case for the conservation of native species after the introduction of four species of rodents – Norway rat, black rat, house mouse, and Pacific rat (kiore) – as well as the possum (introduced for fur), the stoat (to “control rodents”) and the hedgehog (Goldson et al. 2015). The initial focus in this program will be on rats, stoats, and possums. Rat control on islands has already been a major success story for New Zealand scientists (Russell et al. 2016).

Four short-term goals have been set for 2025 for the Predator Free New Zealand project:

  • An additional 1 million hectares of land where pests have been supressed or removed through Predator Free New Zealand partnerships
  • Development of a scientific breakthrough capable of removing at least one small mammal predator from New Zealand entirely
  • Demonstration areas of more than 20,000 hectares that are predator free without the use of fences
  • Complete removal of all introduced predators from offshore island nature reserves

This is a striking vision, and it puts New Zealand at the forefront of global conservation efforts and goals. Everyone appreciates that it will not be easy. In particular there has to be careful attention to the order in which pests are removed. Competition between invasive species as well as predation among them often has counterintuitive results. In New Zealand when rats were removed from experimental plots, house mice increased, and when possums were removed rats increased (Ruscoe et al. 2011). When stoats (Mustela erminea) were removed, there was no effect on rat or mouse abundance, contrary to what a model predicted (Tompkins and Veltman 2006). At the moment there is no clear way to do a total removal of these pest mammals all at once rather than sequentially.

One of the major stimuli for this program has been stopping bovine TB transmission from possums to cattle. The brushtail possum (introduced from Australia) is a disease reservoir and vector of bovine tuberculosis to cattle. Extensive control programs for possums are applied over about 10 million ha in New Zealand by the spreading of 1080 poison baits and trapping, and this program has reduced possum populations to low numbers but not eliminated this pest (Byrom et al. 2016). Poisoning for possum control also reduces stoats and rats, and so has secondary benefits for native biodiversity. A total of approximately NZ$55 million is spent each year on this control program, and if possums could be eradicated, the financial benefits would be great for the cattle industry. Byrom et al. (2016) showed that possum reduction by poisoning had benefits not only for TB transmission but also for increases in vegetation (reduced herbivory), invertebrate, frog and bird abundance.

Two worries are that the social license to continue widespread use of deadly poisons will erode in the future and secondly that the pest species will eventually evolve resistance to the poisons. For these reasons much research is needed on more clever ways of achieving pest reduction and elimination.

The success of island eradications in the past 20 years has emboldened ecologists to wish for successes on larger and larger scales. But eradication is a complex problem and there is a long history of success and failures, particularly in insect populations (Myers et al. 2000). But by reaching out with a direct challenge to applied ecologists, molecular biologists, chemists, and other clever scientists, New Zealand has moved the standard forward in ways that bode well for understanding more why ecology matters.

And then it is on to the feral cats.

Byrom, A.E., Innes, J. & Binny, R.N. (2016) A review of biodiversity outcomes from possum-focused pest control in New Zealand. Wildlife Research, 43, 228-253. doi: 10.1071/WR15132

Campbell, K.J., et al. (2015) The next generation of rodent eradications: Innovative technologies and tools to improve species specificity and increase their feasibility on islands. Biological Conservation, 185, 47-58. doi: 10.1016/j.biocon.2014.10.016

Goldson, S.L., et al. (2015) New Zealand pest management: current and future challenges. Journal of the Royal Society of New Zealand, 45, 31-58. doi: 10.1080/03036758.2014.1000343

Myers, J.H., Simberloff, D., Kuris, A.M. & Carey, J.R. (2000) Eradication revisited: dealing with exotic species. Trends in Ecology and Evolution, 15, 316-320.

Ruscoe, W.A. et al. (2011) Unexpected consequences of control: competitive vs. predator release in a four-species assemblage of invasive mammals. Ecology Letters, 14, 1035-1042. doi: 10.1111/j.1461-0248.2011.01673.x

Russell, J.C. & Broome, K.G. (2016) Fifty years of rodent eradications in New Zealand: another decade of advances. New Zealand Journal of Ecology, 40, 197-204. doi: 10.20417/nzjecol.40.22.

Tompkins, D.M. & Veltman, C.J. (2006) Unexpected consequences of vertebrate pest control: predictions from a four-species community model. Ecological Applications, 16, 1050-1061. doi: 10.1890/1051-0761(2006)016[1050:UCOVPC]2.0.CO;2


Hypothesis testing using field data and experiments is definitely NOT a waste of time

At the ESA meeting in 2014 Greg Dwyer (University of Chicago) gave a talk titled “Trying to understand ecological data without mechanistic models is a waste of time.” This theme has recently been reiterated on Dynamic Ecology Jeremy Fox, Brian McGill and Megan Duffy’s blog (25 January 2016 https://dynamicecology.wordpress.com/2016/01/25/trying-to-understand-ecological-data-without-mechanistic-models-is-a-waste-of-time/).  Some immediate responses to this blog have been such things as “What is a mechanistic model?” “What about the use of inappropriate statistics to fit mechanistic models,” and “prediction vs. description from mechanistic models”.  All of these are relevant and interesting issues in interpreting the value of mechanistic models.

The biggest fallacy however in this blog post or at least the title of the blog post is the implication that field ecological data are collected in a vacuum.  Hypotheses are models, conceptual models, and it is only in the absence of hypotheses that trying to understand ecological data is a “waste of time”. Research proposals that fund field work demand testable hypotheses, and testing hypotheses advances science. Research using mechanistic models should also develop testable hypotheses, but mechanistic models are certainly are not the only route to hypothesis creation of testing.

Unfortunately, mechanistic models rarely identify how the robustness and generality of the model output could be tested from ecological data and often fail comprehensively to properly describe the many assumptions made in constructing the model. In fact, they are often presented as complete descriptions of the ecological relationships in question, and methods for model validation are not discussed. Sometimes modelling papers include blatantly unrealistic functions to simplify ecological processes, without exploring the sensitivity of results to the functions.

I can refer to my own area of research expertise, population cycles for an example here.  It is not enough for example to have a pattern of ups and downs with a 10-year periodicity to claim that the model is an acceptable representation of cyclic population dynamics of for example a forest lepidopteran or snowshoe hares. There are many ways to get cyclic dynamics in modeled systems. Scientific progress and understanding can only be made if the outcome of conceptual, mechanistic or statistical models define the hypotheses that could be tested and the experiments that could be conducted to support the acceptance, rejection or modification of the model and thus to inform understanding of natural systems.

How helpful are mechanistic models – the gypsy moth story

Given the implication of Dwyer’s blog post (or at least blog post title) that mechanistic models are the only way to ecological understanding, it is useful to look at models of gypsy moth dynamics, one of Greg’s areas of modeling expertise, with the view toward evaluating whether model assumptions are compatible with real-world data Dwyer et al.  2004  (http://www.nature.com/nature/journal/v430/n6997/abs/nature02569.html)

Although there has been considerable excellent work on gypsy moth over the years, long-term population data are lacking.  Population dynamics therefore are estimated by annual estimates of defoliation carried out by the US Forest Service in New England starting in 1924. These data show periods of non-cyclicity, two ten-year cycles (peaks in 1981 and 1991 that are used by Dwyer for comparison to modeled dynamics for a number of his mechanistic models) and harmonic 4-5 year cycles between 1943 and1979 and since the 1991 outbreak. Based on these data 10-year cycles are the exception not the rule for introduced populations of gypsy moth. Point 1. Many of the Dwyer mechanistic models were tested using the two outbreak periods and ignored over 20 years of subsequent defoliation data lacking 10-year cycles. Thus his results are limited in their generality.

As a further example a recent paper, Elderd et al. (2013)  (http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3773759/) explored the relationship between alternating long and short cycles of gypsy moth in oak dominated forests by speculating that inducible tannins in oaks modifies the interactions between gypsy moth larvae and viral infection. Although previous field experiments (D’Amico et al. 1998) http://onlinelibrary.wiley.com/doi/10.1890/0012-9658(1998)079%5b1104:FDDNAW%5d2.0.CO%3b2/abstract concluded that gypsy moth defoliation does not affect tannin levels sufficiently to influence viral infection, Elderd et al. (2013) proposed that induced tannins in red oak foliage reduces variation in viral infection levels and promotes shorter cycles. In this study, an experiment was conducted using jasmonic acid sprays to induce oak foliage. Point 2 This mechanistic model is based on experiments using artificially induced tannins as a mimic of insect damage inducing plant defenses. However, earlier fieldwork showed that foliage damage does not influence virus transmission and thus does not support the relevance of this mechanism.

In this model Elderd et al. (2013) use a linear relationship for viral transmission (transmission of infection on baculovirus density) based on two data points and the 0 intercept. In past mechanistic models and in a number of other systems the relationship between viral transmission and host density is nonlinear (D’Amico et al. 2005, http://onlinelibrary.wiley.com/doi/10.1111/j.0307-6946.2005.00697.x/abstract;jsessionid=D93D281ACD3F94AA86185EFF95AC5119.f02t02?userIsAuthenticated=false&deniedAccessCustomisedMessage= Fenton et al. 2002, http://onlinelibrary.wiley.com/doi/10.1046/j.1365-2656.2002.00656.x/full). Point 3. Data are insufficient to accurately describe the viral transmission relationship used in the model.

Finally the Elderd et al. (2013) model considers two types of gypsy moth habitat – one composed of 43% oaks that are inducible and the other of 15% oaks and the remainder of the forest composition is in adjacent blocks of non-inducible pines. Data show that gypsy moth outbreaks are limited to areas with high frequencies of oaks. In mixed forests, pines are only fed on by later instars of moth larvae when oaks are defoliated. The pines would be interspersed amongst the oaks not in separate blocks as in the modeled population. Point 4.  Patterns of forest composition in the models that are crucial to the result are unrealistic and this makes the interpretation of the results impossible.

Point 5 and conclusion. Because it can be very difficult to critically review someone else’s mechanistic model as model assumptions are often hidden in supplementary material and hard to interpret, and because relationships used in models are often arbitrarily chosen and not based on available data, it could be easy to conclude that “mechanistic models are misleading and a waste of time”. But of course that wouldn’t be productive. So my final point is that closer collaboration between modelers and data collectors would be the best way to ensure that the models are reasonable and accurate representations of the data.  In this way understanding and realistic predictions would be advanced. Unfortunately the great push to publish high profile papers works against this collaboration and manuscripts of mechanistic models rarely include data savvy referees.

D’Amico, V., J. S. Elkinton, G. Dwyer, R. B. Willis, and M. E. Montgomery. 1998. Foliage damage does not affect within-season transmission of an insect virus. Ecology 79:1104-1110.

D’Amico, V. D., J. S. Elkinton, P. J.D., J. P. Buonaccorsi, and G. Dwyer. 2005. Pathogen clumping: an explanation for non-linear transmission of an insect virus. Ecological Entomology 30:383-390.

Dwyer, G., F. Dushoff, and S. H. Yee. 2004. The combined effects of pathogens and predators on insect outbreaks. Nature 430:341-345.

Elderd, B. D., B. J. Rehill, K. J. Haynes, and G. Dwyer. 2013. Induced plant defenses, host–pathogen interactions, and forest insect outbreaks. Proceedings of the National Academy of Sciences 110:14978-14983.

Fenton, A., J. P. Fairbairn, R. Norman, and P. J. Hudson. 2002. Parasite transmission: reconciling theory and reality. Journal of Animal Ecology 71:893-905.

On Philanthropic Investment in Biodiversity Conservation

In the holiday season there is much talk and recommendations about donations to worthy causes, and this raises an interesting conundrum in biodiversity conservation. The question is relatively simple to answer if you have little money, but any reading of the business pages of our newspapers or a walk around the shopping centers of our large cities makes you realize that there are a great many people with more than a little money. What should you do with your excess cash?

Some people (but not all) will want to ‘make a difference’ with their accumulated wealth, at least until medical science can overcome the universal belief that “you can’t take it with you”. Peter Singer (2015) has addressed this question of how to spend your money most effectively when you donate. It comes down in the first instance of your time frame. If you wish to make a difference in the short term of a few years, your choices may differ fundamentally from those taken to make a difference in the long term of 100-500 years. The bulk of philanthropic donations now are in the short-term camp. We have poor people living on the street in most of our cities, people with curable diseases in less developed countries but no medical aid, and victims of wars, earthquakes and tsunamis who must rebuild their lives. So we must start with what I think is the biggest decision regarding philanthropy – do we worry only about people, or do we worry about the biological world as well? Most donations are directly related to improving the human condition, locally or globally.

But there is hope because more and more people are realizing that we cannot separate people from biodiversity because of ecosystem services. Without well-functioning ecosystems on Earth, all the medical advances of our time are for naught. This is an important message to convey to potential donors.

Conservation philanthropy is a curious mix of short term and long term goals. Many endangered species need action now to survive. But ecologists typically look at both the shorter and the longer term goals of conservation. The simplest goal is to set aside land for protection. Without habitat all is lost. But this goal must be paired with long term funding to hire rangers to protect the area from poachers and to monitor the status of the species within the protected zone. Relying on the government to do this by itself is not adequate and never has been. But beyond this primary goal of land protection, the conservation movement fractionates. There are arguments that without effective human population stabilization biodiversity loss must continue. So does this mean that effective donations should be earmarked for agencies that empower women and offer reproductive services? But this points out that we must not fall into the trap of thinking we can do only one thing at a time. Pandas or population – why not “both and”? Climate change is a similar ‘elephant in the room’ problem.

What are the long-term goals of conservation biology that would benefit from philanthropic investment? Start with pest control. Biological control of pests is a long-term issue par excellence (Goldson et al. 2015, Myers et al. 2009, Wyckhuys et al. 2013). But biological control programs are underfunded by governments and obtain little private philanthropy. Weed control, insect pest control, vertebrate pest control all fit in the same problem basket – long term problem supported only by short term funding. Invasive pest eradication on islands is one area of pest control in which both governments and private funding have been joining forces (http://www.islandconservation.org/ ) with good results.

Two other areas of conservation biology that are classically underfunded are taxonomy and monitoring. In many taxonomic groups the majority of the species on Earth are not yet identified and described with a scientific name. The nearest analogy would be having a bank with tons of coins of different sizes and shapes, but only a few of which had any engraving on them. Taxonomy which is so vital to biology suffers because physical scientists consider it “stamp collecting” and unworthy of scientific funding. Monitoring of ecological communities faces the same problem. Monitoring ecological communities is similar to monitoring weather, yet we support meteorological stations around the world but provide little support for ecological monitoring. At present ecological monitoring is done ad hoc by dedicated people but with little systematic organization. Monitoring of changes in the arctic is being coordinated globally (http://www.amap.no/ ) and specific programs have been outlined for example for northern Canada (https://www.ec.gc.ca/faunescience-wildlifescience/, but the funding levels are low considering the size of the areas under consideration. Tropical ecosystem monitoring is even less well funded, yet that is where much of global biodiversity is located (c.f. for example, Cardoso et al. 2011, Burton 2012).

So what can you do about this? Talk up the necessity and the advantages of conservation biodiversity. Imagine what would happen to any of these biodiversity problems if a foundation the size of the Bill & Melinda Gates Foundation devoted a large amount of its donations to conservation. Environmental stewardship is the key to the Earth’s survival, and a combination of problem solving of current biodiversity problems combined with a strong research component on how species interact and ecosystems operate to sustain themselves would be a legacy for future generations and a flagship for the next 100 years.

Burton, A.C. (2012) Critical evaluation of a long-term, locally-based wildlife monitoring program in West Africa. Biodiversity and Conservation, 21, 3079-3094. doi: 10.1007/s10531-012-0355-6

Cardoso, P., Erwin, T.L., Borges, P.A.V. & New, T.R. (2011) The seven impediments in invertebrate conservation and how to overcome them. Biological Conservation, 144, 2647-2655. doi: 10.1016/j.biocon.2011.07.024

Glen, A.S., Atkinson, R., Campbell, K.J., Hagen, E., Holmes, N.D., Keitt, B.S., Parkes, J.P., Saunders, A., Sawyer, J. & Torres, H. (2013) Eradicating multiple invasive species on inhabited islands: the next big step in island restoration? Biological Invasions, 15, 2589-2603. doi: 10.1007/s10530-013-0495-y

Goldson, S.L., Bourdôt, G.W., Brockerhoff, E.G., Byrom, A.E., Clout, M.N., McGlone, M.S., Nelson, W.A., Popay, A.J., Suckling, D.M. & Templeton, M.D. (2015) New Zealand pest management: current and future challenges. Journal of the Royal Society of New Zealand, 45, 31-58. doi: 10.1080/03036758.2014.1000343

Myers, J.H., Jackson, C., Quinn, H., White, S.R. & Cory, J.S. (2009) Successful biological control of diffuse knapweed, Centaurea diffusa, in British Columbia, Canada. Biological Control, 50, 66-72. doi: 10.1016/j.biocontrol.2009.02.008

Singer, P. (2015) The Most Good You Can Do. Yale University Press, New Haven. ISBN: 978-0-300-18027-5

Wyckhuys, K.A.G., Lu, Y., Morales, H., Vazquez, L.L., Legaspi, J.C., Eliopoulos, P.A. & Hernandez, L.M. (2013) Current status and potential of conservation biological control for agriculture in the developing world. Biological Control, 65, 152-167. doi: 10.1016/j.biocontrol.2012.11.010 http://www.islandconservation.org/where-we-work/


On Funding for Agricultural Research

One of the most important problems of our day is the interaction between human population growth and the maintenance of sustainable agriculture in the face of climate change. I am currently sitting at the International Rice Research Institute (IRRI) near Manila where I am told they are responding to a 15-20% reduction in funding for their work. I have found this funding situation to be so ridiculous that I have decided to write this blog. Please stop reading if you think agricultural research already has too much funding, or that climate change and sustainable agriculture are not very important issues in comparison to our need for economic growth and increased wealth.

The critical issues here in Southeast Asia are the increasing human population and the productivity of rice agriculture. IRRI has done and is doing outstanding research to raise production of rice with new varieties and to control pests of rice with clever techniques that minimize the spreading of poisons, which everyone agrees must be minimized to protect agricultural and natural ecosystems. Present research concentrates on the ‘yield gap’, the difference between the actual production from farmer’s fields and the maximum possible yield that can be achieved with the best farm practices. The yield gap can be closed with more research by both social and natural scientists, but that is what is under stress now. IRRI operates with funding from a variety of governments and from private donors. Research funds are now being reduced from many of these sources, and the usual explanation is the faltering global economy combined with the severe refugee problems in the Middle East.

Consequently we now do not have enough money to support the most important research on a crop – rice – that is the essential food of half of the Earth’s human population. And it is not just research on rice that is being reduced, but that on corn, wheat, and any other crop you wish to name. Governments of developed countries like Canada, Australia and the USA are reducing their funding of agricultural research. Anyone who likes to eat might think this is the most ridiculous decision of all because agricultural research is an essential part of poverty reduction in the world and overall human welfare. So I ask a simple question – Why? How is it that you can visit any city in a developed country and see obscene excesses of wealth defined in any way you wish? Yet our governments continue to tell us that we are taxed too much, and we cannot afford more foreign aid, and that if we raised the taxation rate to help the poor of the Earth, our countries would all collapse economically. Yet historically taxes have often been raised during World Wars with general agreement that we needed to do so to achieve society’s goals. The goal now must be poverty reduction and sustainability in agriculture as well as in population. Important efforts are being done on these fronts by many people, but we can and must do more if we wish to leave a suitable Earth for future generations.

At the same time this shortage of funding should not all be laid at the feet of governments. Private wealth continues to increase in the world, and private gifts to research agencies like IRRI and to universities are substantial. But if we believe Piketty (2014), the rich will only get richer in the present economic climate and perhaps the message needs to be sent that donations are long overdue from the wealthy to establish foundations devoted to the problems of sustainability in agriculture, population, and society, as well as the protection of biodiversity. The inactions of people and governments in the past are well documented in books like Diamond (2005). Many scientific papers are mapping and have mapped the way forward to achieve a sustainable society (e.g. Cunningham et al. 2013). To make effective progress we must begin reinvestment in agriculture while not neglecting the human tragedies of our time. It can be both-and rather than either-or.

Cunningham, S.A., et al. (2013) To close the yield-gap while saving biodiversity will require multiple locally relevant strategies. Agriculture, Ecosystems & Environment, 173, 20-27. doi 10.1016/j.agee.2013.04.007

Diamond, J. (2005) Collapse: How Societies Choose to Fail or Succeed. Viking, New York. 575 pp. ISBN: 0670033375

Piketty, T. (2014) Capital in the Twenty-First Century. Belknap Press, Harvard University, Boston. 696 pp. ISBN 9780674430006

On Sequencing the Entire Biosphere

There is an eternal war going on in science which rests on the simple question of “What should we fund?” If you are at a cocktail party and want to set up a storm of argument you should ask this question. There may be general agreement among many scientists that we should reduce funding on guns and wars and increase funding on alleviating poverty. But then the going gets tough. It is easier to restrict our discussion to science. There is a clear hierarchy in science funding favouring the physical sciences that can make money and the medical sciences that keep us alive until 150 years of age. But now let’s go down to biology.

The major rift in biology is between funding blue sky research and practical research. In the discussions about funding, protagonists often confound these two categories by saying that blue sky research will lead us to practical research and nirvana. We can accept salesmanship to a degree. The current bandwagon in Canada is to barcode all of life on earth, at a cost of perhaps $2 billion but probably much more. Or we can sequence everything we can get our hands on with the implicit promise that it will help us understand these organisms better or solve practical problems in conservation and management. But all of this is driven by what we can do technically, so it is machine driven, not necessarily thought driven. So if you want another heated discussion among ecologists, ask them how they would spend $2 billion for research in ecology.

We sequence because we can. Fifty years ago I heard a lecture by Richard Lewontin in which he asked what we would know if we had a telephone book with all the genetic sequences of all the organisms on earth. He concluded, as I remember, that we would know nothing unless we had a purely ‘genetic-determinism’ view of life. There is more to life than amino acid sequences perhaps.

No one I know thinks that current ecological changes are driven by genetics, but perhaps I do not know the right people. So for example, if we sequence the genomes of all the top predators on earth (Estes et al. 2011, Ripple et al. 2014), would we know anything about their importance in community and ecosystem dynamics? Probably not. But still we are told that if in New Zealand we sequence the common wasp genome we will find new ways to control this insect pest. Perhaps an equally important area would be funding to understand their biology in New Zealand, and the threats and threatening processes in an ecosystem context.

We are back to the starting question about the allocation of resources within biology. Perhaps we cycle endlessly in science funding in search of the Promised Land. In a recent paper Richards (2015) makes the argument that genome sequencing is the key to biology and thus the Promised Land:

“The unifying theme of biology is evolutionary conservation of the gene set and the resultant proteins that make up the biochemical and structural networks of cells and organisms throughout the tree of life.”

“The absence of these genome references is not just slowing research into specific questions; it is precluding a complete description of the molecular underpinnings of biology necessary for a true understanding of life on our planet.” (p. 414)

There seems little room in all this for ecological thought or ecological viewpoints. It is implicit to me that these arguments for genome sequencing have as a background assumption that ecological research is rather useless for achieving biological understanding or for solving any of the problems we currently face in conservation or management. Richards (2015) makes the point himself in saying:

“While the author is fond of ‘stamp collecting’, there are many good reasons to expand the reference sequences that underlie biological research (Table 2).”

The table he refers to in his paper has not a single item on ecological research, except that this approach will achieve “Acceleration of total biological research output”. It remains to be seen whether this view will achieve much more than stamp collecting and a massive confusion of correlation with causation. It requires a great leap of faith that this approach through genome sequencing can help to solve practical ecological problems.

Richards, S. (2015) It’s more than stamp collecting: how genome sequencing can unify biological research. Trends in Genetics, 31, 411-421.

Estes, J.A., et al. (2011) Trophic downgrading of Planet Earth. Science, 333, 301-306.

Ripple, W.J., et al. (2014) Status and ecological effects of the world’s largest carnivores. Science, 343, 1241484.

The Anatomy of an Ecological Controversy – Dingos and Conservation in Australia

Conservation is a most contentious discipline, partly because it is ecology plus a moral stance. As such you might compare it to discussions about religious truths in the last several centuries but it is a discussion among scientists who accept the priority of scientific evidence. In Australia for the past few years there has been much discussion of the role of the dingo in protecting biodiversity via mesopredator release of foxes and cats (Allen et al. 2013; Colman et al. 2014; Hayward and Marlow 2014; Letnic et al. 2011, and many more papers). I do not propose here to declare a winner in this controversy but I want to dissect it as an example of an ecological issue with so many dimensions it could continue for a long time.

Dingos in Australia are viewed like wolves in North America – the ultimate enemy that must be reduced or eradicated if possible. When in doubt about what to do, killing dingos or wolves has become the first commandment of wildlife management and conservation. The ecologist would like to know, given this socially determined goal, what are the ecological consequences of reduction or eradication of dingos or wolves. How do we determine that?

The experimentalist suggests doing a removal experiment (or conversely a re-introduction experiment) so we have ecosystems with and without dingos (Newsome et al. 2015). This would have to be carried out on a large scale dependent on the home range size of the dingo and for a number of years so that the benefits or the costs of the removal would be clear. Here is the first hurdle, this kind of experiment cannot be done, and only a quasi-experiment is possible by finding areas that have dingos and others that do not have any (or a reduced population) and comparing ecosystems. This decision immediately introduces 5 problems:

  1. The areas with- and without- the dingo are not comparable in many respects. Areas with dingos for example may be national parks placed in the mountains or in areas that humans cannot use for agriculture, while areas with dingo control are in fertile agricultural landscapes with farming subsidies.
  2. Even given areas with and without dingos there is the problem of validating the usual dingo reduction carried out by poison baits or shooting. This is an important methodological issue.
  3. One has to census the mesopredators, in Australia foxes and cats, with further methodological issues of how to achieve that with accuracy.
  4. In addition one has to census the smaller vertebrates presumed to be possibly affected by the mesopredator offtake.
  5. Finally one has to do this for several years, possibly 5-10 years, particularly in variable environments, and in several pairs of areas chosen to represent the range of ecosystems of interest.

All in all this is a formidable research program, and one that has been carried out in part by the researchers working on dingos. And we owe them our congratulations for their hard work. The major part of the current controversy has been how one measures population abundance of all the species involved. The larger the organism, paradoxically the more difficult and expensive the methods of estimating abundance. Indirect measures, often from predator tracks in sand plots, are forced on researchers because of a lack of funding and the landscape scale of the problem. The essence of the problem is that tracks in sand or mud measure both abundance and activity. If movements increase in the breeding season, tracks may indicate activity more than abundance. If old roads are the main sampling sites, the measurements are not a random sample of the landscape.

This monumental sampling headache can be eliminated by the bold stroke of concluding with Nimmo et al. (2015) and Stephens et al. (2015) that indirect measures of abundance are sufficient for guiding actions in conservation management. They may be, they may not be, and we fall back into the ecological dilemma that different ecosystems may give different answers. And the background question is what level of accuracy do you need in your study? We are all in a hurry now and want action for conservation. If you need to know only whether you have “few” or “many” dingos or tigers in your area, indirect methods may well serve the purpose. We are rushing now into the “Era of the Camera” in wildlife management because the cost is low and the volume of data is large. Camera ecology may be sufficient for occupancy questions, but may not be enough for demographic analysis without detailed studies.

The moral issue that emerges from this particular dingo controversy is similar to the one that bedevils wolf control in North America and Eurasia – should we remove large predators from ecosystems? The ecologist’s job is to determine the biodiversity costs and benefits of such actions. But in the end we are moral beings as well as ecologists, and for the record, not the scientific record but the moral one, I think it is poor policy to remove dingos, wolves, and all large predators from ecosystems. Society however seems to disagree.


Allen, B.L., Allen, L.R., Engeman, R.M., and Leung, L.K.P. 2013. Intraguild relationships between sympatric predators exposed to lethal control: predator manipulation experiments. Frontiers in Zoology 10(39): 1-18. doi:10.1186/1742-9994-10-39.

Colman, N.J., Gordon, C.E., Crowther, M.S., and Letnic, M. 2014. Lethal control of an apex predator has unintended cascading effects on forest mammal assemblages. Proceedings of the Royal Society of London, Series B 281(1803): 20133094. doi:DOI: 10.1098/rspb.2013.3094.

Hayward, M.W., and Marlow, N. 2014. Will dingoes really conserve wildlife and can our methods tell? Journal of Applied Ecology 51(4): 835-838. doi:10.1111/1365-2664.12250.

Letnic, M., Greenville, A., Denny, E., Dickman, C.R., Tischler, M., Gordon, C., and Koch, F. 2011. Does a top predator suppress the abundance of an invasive mesopredator at a continental scale? Global Ecology and Biogeography 20(2): 343-353. doi:10.1111/j.1466-8238.2010.00600.x.

Newsome, T.M., et al. (2015) Resolving the value of the dingo in ecological restoration. Restoration Ecology, 23 (in press). doi: 10.1111/rec.12186

Nimmo, D.G., Watson, S.J., Forsyth, D.M., and Bradshaw, C.J.A. 2015. Dingoes can help conserve wildlife and our methods can tell. Journal of Applied Ecology 52. (in press, 27 Jan. 2015). doi:10.1111/1365-2664.12369.

Stephens, P.A., Pettorelli, N., Barlow, J., Whittingham, M.J., and Cadotte, M.W. 2015. Management by proxy? The use of indices in applied ecology. Journal of Applied Ecology 52(1): 1-6. doi:10.1111/1365-2664.12383.

Why We Cannot Forget about Weeds

Weeds are one of world’s most significant ecological problems. As such it is surprising that the word “weeds” does not appear at all in Sutherland et al. (2013), and only once in Sutherland et al. (2006). (Perhaps there are no weeds in the UK.) Weeds affect plant and animal communities in national parks and nature reserves as well as in agricultural landscapes and cities. We have taken a benign neglect attitude toward weeds, perhaps because they are everywhere, but ecologists may also wish to avoid the word ‘weed’ because it is not a useful aggregate term about which we can draw some ecological generalizations. How should we respond to weeds?

I consider ‘weeds’ as a collective term for what might be the worst global example of serious ecological problems (Strayer 2012). But is this collective term a very useful one? At the first step when we deal only with plants, we get confused with native plants and exotic plants. A utilitarian perspective looks at all plants to see if they are useful or harmful for humans. So some conservation biologists want to get rid of all exotic plants outside of gardens and crops, and others wish to limit all harmful plants, whether native or exotic, and call them ‘weeds’. So the rose in your front yard is indeed an exotic species but a good one. Farmers want to get rid of at least some weeds to maximize production but at the same time to tolerate other exotic species that increase production. Weeds might be thought of as a convenient grouping to simplify ecological generalizations. But alas it has not been so.

The War against Weeds is in general not going well for conservation biologists (Downey et al. 2010). While biological control is very useful for some weeds, it does not at present seem to work for most weeds of national concern. So it does not seem to be a universal solution. Herbicides work for a time and then natural selection intervenes. The problem is that weed problems are very much a local problem in being species-specific and environment-specific, so that there is no overall weed strategy that works everywhere (Vilà et al. 2011). If one is interested in community productivity, weeds may increase plant biomass which might be considered a good result for the ecosystem. Graziers may encourage weeds that plant ecologists would consider destructive to natural communities. Ecosystem ecologists might welcome weeds that increase plant cover if they reduce soil erosion and nutrient leakage into water bodies.

This conflict of interest comes home to us in quarantine restrictions on weeds. In Australia government research scientists work to increase the tolerance of exotic pasture grassess to cold and drought, even though the species in question is a weed of national significance, and improving it genetically will make it more invasive in natural communities (Driscoll et al. 2014). The problem comes back to who wants what kind of an ecological world. Generalist grazing mammals may care little about the exact species composition of the grasslands they inhabit, or alternately they may be poisoned by specific weeds that are toxic to farm animals. The devil rests in the details, so the general message is that we cannot forget species names and attributes in the War on Weeds.

As a minimum, we ought to encourage our governments to place quarantine restrictions on all plant species listed as global weeds of significance. For the present time the best predictor of whether or not an introduced plant will become a destructive weed is: what happened to that plant in other countries to which it was introduced? That you can still buy at your local plant store the seeds of an array of weeds of national significance shouts to ecologists that quarantine systems needs to be strengthened. The War on Weeds is greatly under-financed like many long term problems in ecology, and we should put more effort into developing tactics to deal with destructive weeds rather than ignoring them.

Downey, P.O. et al. 2010. Managing alien plants for biodiversity outcomes—the need for triage. Invasive Plant Science and Management 3(1): 1-11. doi:10.1614/ipsm-09-042.1.

Driscoll, D.A. et al. 2014. New pasture plants intensify invasive species risk. Proceedings of the National Academy of Sciences USA 111(46): 16622-16627. doi:10.1073/pnas.1409347111.

Strayer, D.L. 2012. Eight questions about invasions and ecosystem functioning. Ecology Letters 15(10): 1199-1210. doi:10.1111/j.1461-0248.2012.01817.x.

Sutherland, W.J. et al. 2006. The identification of 100 ecological questions of high policy relevance in the UK. Journal of Applied Ecology 43(4): 617-627. doi:10.1111/j.1365-2664.2006.01188.x.

Sutherland, W.J. et al. 2013. Identification of 100 fundamental ecological questions. Journal of Ecology 101(1): 58-67. doi:10.1111/1365-2745.12025.

Vilà, M., et al. 2011. Ecological impacts of invasive alien plants: a meta-analysis of their effects on species, communities and ecosystems. Ecology Letters 14(7): 702-708. doi:10.1111/j.1461-0248.2011.01628.x.

On House Mouse Outbreaks in Australia

It occurred to me after some recent discussions that the problem of house mouse outbreaks in Australia is almost a paradigm for modern ecological science. A brief synopsis. At irregular intervals house mice (an introduced pest) reach high densities in the wheat growing areas of eastern and southern Australia, and cause serious damage to wheat, barley, oats, and sunflower crops. There are two approaches to this applied problem.

The ecological approach is to understand why these outbreaks occur and why for many years (2-9 years) between outbreaks, hardly a mouse can be found. This approach has been highly successful led by a series of excellent Australian ecologists over the last 40 years. The key limitation is food, combined with social interactions, and the food supply is driven by rain at critical times of the year to provide seeds for the mice. There are no competitors for house mice, and there are a few insignificant predators, overwhelmed by the mouse’s high reproductive rate. These ecological facts are clearly known, and the job now is to build the best predictive models to help the farmers anticipate when the outbreak is coming. There are still important ecological questions to be studied, to be sure, but the broad outline of the ecological play is well described.

The management approach is much simpler because farmers can control house mice with poison, primarily zinc phosphide, and for them the question is when to poison, and secondarily (over time and with more research) can we develop better poisons so there are few non-target problems. Poisoning costs time and money so good farmers wish to minimize these costs.

The long-term issues get lost in this situation, a model of the way the world operates now with ecological and environmental problems. Questions about sustainability multiply in any system dependent on poisons for a solution. Will the target organisms become resistant so the poison does not work? Many examples exist of this already. Are there any long-term problems with soil organisms, or non-target species? No research yet on these issues, and perhaps they are more serious with herbicide applications in agriculture. And while predators do not control house mice during outbreaks, they do eat many of them and this food pulse may have implications for the wider ecosystem. We focus on farming and forget the wider ecosystem which has no dollars attached to it.

Ecologists recognize that these issues are not the farmers’ fault, but we raise the question of who worries about the long-term future of this system, and the answers to these long-term questions. The government is rushing to get out of long-term ecological and agricultural research and we leave problems that do not have immediacy.

Consequently we become short-sighted as a society. Long-term research becomes 1-3 years and not the 50-100 years that ecologists would support. And consequently applied ecologists bounce from one problem to the next under the paradigm that, no matter what we do, science will come up with a technological fix. There should be a better way. To go back to our house mice, we might ask (for example) if we implement no-till agriculture, what will be the consequences for house mouse survival and future outbreaks? The practical minister of agriculture will respond that we have no time or money for such research, so we lurch along, managing the world in an ad-hoc manner. There should be a better way. But meanwhile we must follow the money.