Category Archives: wildlife management

On Cats and Birds and Policy Gaps

1 Reply

Many people in western societies like to keep cats as pets, and with that simple observation we run into two problems that require resolution. First, cats are killers of wildlife, particularly birds but also an array of other small prey. Most people do not believe this, because cats are adored and make good, if somewhat disinterested pets. So, my first point might be that if you think cats are not killers, I invite you to keep another cat like a mountain lion for a pet. But we need some data on the kill rate of cats. Before we begin this search, we should note that cats can be kept inside dwellings or in cat runs with no access to birds or other prey. If this is the case, no problem exists for wildlife, and you can skip to the bottom of this blog for one other issue to recognize.

How much mortality can be traced to cats roaming out of doors? This will include normal house cats let out to roam at night, as well as wild cats that have been discarded by their owners into the wild. There is extensive literature on cats killing birds. If you want a brief introduction Greenwall et al. (2019) discuss a nesting colony of Fairy Terns, a threatened species of Australian seabird, along a beach in southwestern Australia. With detailed observations and photographic data, they recorded the complete failure of all 111 nests in this colony with the loss of all tern chicks in the early summer of 2018. The predator was a single desexed feral cat. Many local governments allow the capture of feral cats with the protocol that they are desexed and then released back into the environment. Clearly desexing and release does not remove the problem.

The domestic cat has been spread world-wide, so that the cat problem is not a local one. Li et al. (2021) completed a survey of feral cat kill rates in the eastern part of China and found that the minimum annual loss of wildlife to feral cats was in the range of 2.7-5.5 billion birds, and 3.6-9.8 billion mammals, as well as large numbers of amphibians, reptiles, and fish. In gardens in Western Europe cat predation on ringed birds studied with precise data showed that up to 25% of dead birds were killed by cats, but these data varied greatly among species (Pavisse et al. 2019). For the European Robin which often feeds on the ground 40% of all ringed birds were killed by cats, for the European Greenfinch the figure was 56% of ringed birds killed. These are just two examples of an extensive literature on cat kills going back many years (Calvert et al. 2013).

What can we do about this predation? As with too many conservation issues the answer is simple but difficult to implement: Ban all cats from free-ranging unless they are on a leash and under control. Keep cats in the house or in special cat runs that are confined outdoors. Ban completely stupid programs of catching feral cats, sterilizing them, and releasing them back to the wild to continue their killing. Cats may make marvellous pets but need to be kept indoors. Many people would support these measures but many cat owners would disagree about such measures. Some progress is being made in urban environments in which some suburbs do not permit cats to roam freely.

Feral cats are a serious issue in Australia because they attack many threatened birds and reptiles (Doherty et al. 2019). In this case a federal environmental policy to kill 2 million cats is popular but from a conservation viewpoint still a poor policy. We do not know if killing 2 million cats is too much or too few, and without specific goals for conservation and careful monitoring of bird populations widespread killing my not achieve the goal of protection for threatened species. Eradications of cats on islands is often feasible, but no mainland eradication is currently possible.

As conservation biologists know too well, when humans are the problem, wise policies may not be implemented. So, the second issue and the bottom line might be to consider the human costs of cat ownership. Adhikari et al. (2020) report a highly significant association between the risk of dying from colon cancer and cat ownership. These results are not confounded by sedentary lifestyle, cigarette smoking or socio-economic status. In a similar study Adhikari et al. (2019) found that living with a cat significantly increased the death rate from lung cancer among women. The cause of these associations cannot yet be deciphered but are postulated to result from mycotoxins, toxic secondary metabolites produced by fungi (moulds) in cereal crops used in cat food. Aflatoxin is a mycotoxin that produces well-known chemicals that are seriously toxic to animals and humans.

These kinds of studies of associations arising from surveys can be tossed off by the typical comments ‘these-things-do-not-concern-my cats’ or ‘that there is no proof of the exact cause’ so if you are concerned you might investigate the literature on both mycotoxins and the diseases that cats carry.

It is up to humans to solve human problems, but up to conservation biologists to point out the detrimental effects of household pets and their feral cousins on wildlife. The present situation is a complete policy failure by governments at all levels. Good science is relatively easy, good policy is very difficult.

Adhikari, Atin, Adhikari, A., Jacob, N. K., and Zhang, J. (2019). Pet ownership and the risk of dying from lung cancer, findings from an 18 year follow-up of a US national cohort. Environmental Research 173, 379-386. doi: 10.1016/j.envres.2019.01.037.

Adhikari, Atin, Adhikari, A., Wei, Y. D., and Zhang, J. (2020). Association between pet ownership and the risk of dying from colorectal cancer: an 18-year follow-up of a national cohort. Journal of Public Health 28, 555-562. doi: 10.1007/s10389-019-01069-1.

Calvert, A.M., Bishop, C.A., Elliot, R.D., Krebs, E.A., Kydd, T.M., Machtans, C.S., Robertson, G.J., 2013. A synthesis of human-related avian mortality in Canada. Avian Conservation and Ecology 8: 11. doi 10.5751/ACE-00581-080211.

Doherty, T.S., Driscoll, D.A., Nimmo, D.G., Ritchie, E.G., and Spencer, R. (2019). Conservation or politics? Australia’s target to kill 2 million cats. Conservation Letters 12, e12633. doi: 10.1111/conl.12633.

Li, Yuhang, Wan, Yue, Shen, Hua, Loss, S.R., Marra, P.P., and Li, Zhongqiu (2021). Estimates of wildlife killed by free-ranging cats in China. Biological Conservation 253, 108929. doi: 10.1016/j.biocon.2020.108929.

Greenwell, C.N., Calver, M.C., and Loneragan, N.R. (2019). Cat Gets Its Tern: A Case Study of Predation on a Threatened Coastal Seabird. Animals 9, 445. doi: 10.3390/ani9070445.

Pavisse, R., Vangeluwe, D., and Clergeau, P. (2019). Domestic Cat Predation on Garden Birds: An Analysis from European Ringing Programmes. Ardea 107, 103-109. doi: 10.5253/arde.v107i1.a6.

A Few Problems Ecologists Need to Face

Leave a reply

This is an overly simple attempt to look ahead, after a summer of extreme heat, extensive forest fires, overheated crops, and excessive flooding, to ask where we ecologists might be going in the next century. 

The first and most important point is that these disasters of the last several months can all be blamed on climate change, and despite what you hear, there is no stopping these changes in the next hundred years. CO2 enrichment is turning Earth into a hot planet. This is a simple fact of physics that the CO2 we have already emitted into our atmosphere will be there for hundreds to thousands of years. The politicians and the media will tell you that carbon-capture is coming soon to solve all our emission problems and cleanse the atmosphere of excess greenhouse gases. If you believe that, ask yourself if you would invest your capital and retirement account in a poker game for a decline in CO2 during the next 20 years.

The critical question for we ecologists is this: How much of the accumulated ecological wisdom will be unchanged in 100 years? If we have only to deal with changing climate, we could develop an understanding of what the limiting factors are and express the anticipated changes in the climatic units of the future. But that becomes a problem when we recognize that food webs have many interactions in them that are climate affected but perhaps not climatically determined. So, for example if we have a simple food web of polar bears feeding on seals, both of which require an ice pack for survival at the present time, what should we expect in 100 years when there is virtually no polar ice to be found. A simple model will predict that the polar bear will go extinct and perhaps seals will learn to use land instead of ice packs, but the fish that are the main food of the seals may also change if they depend on zooplankton that have a water temperature niche boundary that is exceeded. So exactly what will happen to this simple food web cannot be easily understood from current ecological wisdom or models.

Another example is from the current changing dynamics of Stellar sea lions of the North Pacific, summarized in an excellent review by Andrew Trites (2021). Stellar sea lions occupy the coastlines of the North Pacific from the Sea of Okhotsk and the Bering Sea eastward down the west coast of North America to southern California. Forty years ago, scientists noted a decline beginning in the western sea lion populations in the Bering Sea and the Gulf of Alaska and at the same time an increase in sea lion numbers from Southeast Alaska to California. Two explanations compete among seal experts to explain this pattern. The ‘overfishing hypothesis’ suggested that the Alaskan and Russian fishery has removed too much of the sea lion’s favourite food items and thus caused starvation among western sea lions. The alternative to this explanation, the ‘junk-food-hypothesis’ suggested that sea lions in the west were consuming too many fish species of low fat and fewer calories, and that their starvation was self-limited and not caused by the human fisheries.

Here is a “simple” ecological problem with 2 competing hypotheses or explanations that has not yet been resolved after many years of research. Empirical ecologists will possibly argue that we need to monitor the sea lions and their prey and the fishing catches over this extensive area for the next decade or two to find the answer as to which of the two competing hypothesis is closest to being correct. But given climate change and ocean warming, neither of which are uniform over all parts of the Earth, we would expect large changes in the abundance and distribution of many fish species and consequently also in the predators that depend on them. But exactly which ones, and exactly where? Conservation ecology is dogged by this problem and subsists largely by ignoring it in favour of short-term studies in small areas and the effects of human population growth, and perhaps this is all we can do at present. So, should “watch and wait, look and see” become our model? Wildlife and fisheries management thus become short-term ‘watch and wait’ sciences, like passengers on the Titanic long ago, wondering what the future holds.

One way to suggest future paths is to model the various communities and ecosystems that we study, and this activity is now strong in ecology and conservation. But there are many difficulties with this approach boiling down to a ‘wait-and-see’ method of empirical investigation. A review by Furtado (2020) of two books on fisheries management provides an up-to-date view of progress in fisheries ecology and illustrates problems with bluefin tuna management and the modelling approach to fish ecosystems in general. The problem in assuming the modelling approach as an answer to our dilemma is shown clearly by the current Covid pandemic and the reversals in modelling and alternative views that have caused much confusion despite much important research. Whither ecology from this point in time?

Furtado, Miguel (2020). The Future of Bluefin Tunas: Ecology, Fisheries Management and Conservation. Conservation Biology 34, 1600-1602.

Trites, A.W. (2021). Behavioral Insights into the Decline and Natural History of Steller Sea Lions. In ‘Ethology and Behavioral Ecology of Otariids and the Odobenid, Ethology and Behavioral Ecology of Marine Mammals,’. (Ed. C. Campagna and R. Harcourt), pp. 489-518. (Springer Nature Switzerland.)  doi: 10.1007/978-3-030-59184-7_23  

The Crunch is Here

Leave a reply

There are times when we either act or give up, so if you think that the Covid epidemic, the conservation of endangered species, and the protection of old growth forests are irrelevant problems to your way of life, stop reading here. These three major problems are here and now and have come to a head as a crunch: do something or quit.

The Covid epidemic is the most obvious of the current crises and it is on the radio and TV every day with an array of instructions of how to avoid this virus disease. You can respond to all this in three ways: ignore the problem because you are immortal, take a few precautions when you have time but minimize inconvenience, or take the mortality rate and the sickness rate of Covid to heart and do all you can to prevent infection or spread of infection. In the third wave of this virus, too many people in North America are taking option 1 and 2, perhaps in the hope that the vaccines arriving now will solve the problem of infection. If you think the pandemic will go away without much death and disruption, read Kolata (2019) or one of the many good books on pandemics in history (e.g., Kelly (2006). They are with us and our governments must take note.

Of less visibility in the news media are conservation issues that are equally at a crunch point. The most obvious one in Canada is the decline of mountain caribou, and the current status of conservation efforts on their behalf. Nagy-Reis et al. (2021) have recently reported on the lack of success to date in conserving mountain caribou. We have known for more than 20 years that habitat loss and habitat changes were the critical factors driving mountain caribou populations in Western Canada to extinction. Forest cover within the caribou range is the key indicator for caribou conservation, and forest harvest is the main cause of habitat loss added to by forest fires in more northern areas. From 2000 to 2018 caribou lost twice as much habitat as they gained by restoration policies from forest companies and the governments involved. Loss rates of habitat in different subregions of Western Canada ranged from about 1% per year to 8% per year loss. If we had a bank account with these continued losses over 20 years, we would start a revolution. The accepted policies are failing caribou. Seismic lines that break up caribou habitat are regenerating at a slow rate. Changes in land use management must be implemented to prevent extinction but the crunch comes there – jobs in the forestry industry vs. conservation goals that do not generate cash for governments. Temporary fixes like wolf control will help, but as Nagy-Reis et al. (2021) point out are not sufficient to solve the problem. If we wish to reverse these caribou declines, we must make long-term commitments to land use planning and reduce human alterations of landscapes. 

The third problem in which crunch time is coming is the loss of old growth forests, and thus is related to some extent to the caribou conservation issue. Old growth forest is disappearing globally and in any country on Earth you can hear the cry (e.g. Lindenmayer et al. 2020, Watson et al. 2018). In British Columbia now you must drive many hours to see old growth (3 meters diameter) and they are still logging these stands. The reason for this is the clever foresters who classify “old growth” in this province, so that in their arithmetic at present 26% of our forests are called ‘old growth’. At high elevations many ‘old growth’ stands are small trees, and at one extreme old growth in terms of age could be Krummholz (‘knee timber’) < 1 m tall. The government classifies old growth in wetter areas as stands of 250 years or more in age, and in dryer areas trees of 140 years old, primarily because the logging companies so far have not wanted to log such “small” trees. Price et al. (2021) analysed the forest structure of British Columbia and classified old growth with a proper definition of a productivity class of trees that will grow to 25 m or more in height by age 150 years. By government definitions B.C. has about 50 million ha of forest, of which 26% is classified as ‘old’growth’. So, this means they believe that 13 million ha of forest in B.C. is old growth. But if you consider the more correct ecological definition of old growth as stated by Price et al. (2021) of trees that will grow > 25 m tall in 50 years you find that <1% of B.C. forest is old growth at the present time. People do not drive for miles to see 5 m trees which they already have in cities. They will drive to see trees that are 800-1000 years old and more than 3 m in diameter, so a common-sense definition of old growth prevails in the tourist population. But again, we are back at jobs in forestry vs tourism potentials and the government is so committed to the forest industry that you have to search hard to find anyone who will give you a public lecture on “old growth” logging. So, this is another crunch for our time, jobs vs some 800-year-old trees with a lot of wood that inspire us and our children as being part of nature. All these considerations do not even begin to consider the other species that are lost in logging old growth because they are small and rarely measured (Doak 1989). The accepted government policies are failing us and our children. It is time to use science to challenge these changes which will affect us all now and in the future.

Doak, D. (1989). Spotted owls and old growth logging in the Pacific Northwest. Conservation Biology 3, 389-396.

Kelly, J. (2006) ‘The Great Mortality: An Intimate History of the Black Death, the Most Devastating Plague of All Time.’ (Harper Perennial: New York.). ISBN: 978-0060-00693-8.

Lindenmayer, D.B., Kooyman, R.M., Taylor, C., Ward, M., and Watson, J.E.M. (2020). Recent Australian wildfires made worse by logging and associated forest management. Nature Ecology & Evolution 4, 898-900. doi: 10.1038/s41559-020-1195-5.

Kolata, G.B. (2019) ‘Flu: The Story of the Great Influenza Pandemic of 1918 and the Search for the Virus that caused it.’ (Atria Books: New York.). ISBN: 978-14299-79351

Nagy-Reis, M., Dickie, M., Calvert, A.M., Hebblewhite, M., Hervieux, D., Seip, D.R., Gilbert, S. L., Venter, O., DeMars, C., Boutin, S., and Serrouya, R. (2021). Habitat loss accelerates for the endangered woodland caribou in western Canada. Conservation Science and Practice (in press), e437. doi: 10.1111/csp2.437 .

Price, K., Holt, R.F., and Daust, D. (2021). Conflicting portrayals of remaining old growth: the British Columbia case. Canadian Journal of Forest Research 51, 1-11. doi: 10.1139/cjfr-2020-0453.

Watson, J.E.M., Evans, T., Venter, O., Williams, B., and Tulloch, A. (2018). The exceptional value of intact forest ecosystems. Nature Ecology & Evolution 2, 599-610. doi: 10.1038/s41559-018-0490-x.

On an Experimental Design Mafia for Ecology

2 Replies

Ecologist A does an experiment and publishes Conclusions G and H. Ecologist B reads this paper and concludes that A’s data support Conclusions M and N and do not support Conclusions G and H. Ecologist B writes to Journal X editor to complain and is told to go get stuffed because Journal X never makes a mistake with so many members of the Editorial Board who have Nobel Prizes. This is an inviting fantasy and I want to examine one possible way to avoid at least some of these confrontations without having to fire all the Nobel Prize winners on the Editorial Board.

We go back to the simple question: Can we agree on what types of data are needed for testing this hypothesis? We now require our graduate students or at least our Nobel colleagues to submit the experimental design for their study to the newly founded Experimental Design Mafia for Ecology (or in French DEME) who will provide a critique of the formulation of the hypotheses to be tested and the actual data that will be collected. The recommendations of the DEME will be nonbinding, and professors and research supervisors will be able to ignore them with no consequences except that the coveted DEME icon will not be able to be published on the front page of the resulting papers.

The easiest part of this review will be the data methods, and this review by the DEME committee will cover the current standards for measuring temperature, doing aerial surveys for elephants, live-trapping small mammals, measuring DBH on trees, determining quadrat size for plant surveys, and other necessary data collection problems. This advice alone should hypothetically remove about 25% of future published papers that use obsolete models or inadequate methods to measure or count ecological items.

The critical part of the review will be the experimental design part of the proposed study. Experimental design is important even if it is designated as undemocratic poppycock by your research committee. First, the DEME committee will require a clear statement of the hypothesis to be tested and the alternative hypotheses. Words which are used too loosely in many ecological works must be defended as having a clear operational meaning, so that idea statements that include ‘stability’ or ‘ecosystem integrity’ may be questioned and their meaning sharpened. Hypotheses that forbid something from occurring or allow only type Y events to occur are to be preferred, and for guidance applicants may be referred to Popper (1963), Platt (1964), Anderson (2008) or Krebs (2019). If there is no alternative hypothesis, your research plan is finished. If you are using statistical methods to test your hypotheses, read Ioannidis (2019).

Once you have done all this, you are ready to go to work. Do not be concerned if your research plan goes off target or you get strange results. Be prepared to give up hypotheses that do not fit the observed facts. That means you are doing creative science.

The DEME committee will have to be refreshed every 5 years or so such that fresh ideas can be recognized. But the principles of doing good science are unlikely to change – good operational definitions, a set of hypotheses with clear predictions, a writing style that does not try to cover up contrary findings, and a forward look to what next? And the ecological world will slowly become a better place with fewer sterile arguments about angels on the head of a pin.

Anderson, D.R. (2008) ‘Model Based Inference in the Life Sciences: A Primer on Evidence.‘ (Springer: New York.) ISBN: 978-0-387-74073-7.

Ioannidis, J.P.A. (2019). What have we (not) learnt from millions of scientific papers with P values? American Statistician 73, 20-25. doi: 10.1080/00031305.2018.1447512.

Krebs, C.J. (2020). How to ask meaningful ecological questions. In Population Ecology in Practice. (Eds D.L. Murray and B.K. Sandercock.) Chapter 1, pp. 3-16. Wiley-Blackwell: Amsterdam. ISBN: 978-0-470-67414-7

Platt, J. R. (1964). Strong inference. Science 146, 347-353. doi: 10.1126/science.146.3642.347.

Popper, K. R. (1963) ‘Conjectures and Refutations: The Growth of Scientific Knowledge.’ (Routledge and Kegan Paul: London.). ISBN: 9780415285940

On the Use of Statistics in Ecological Research

1 Reply

There is an ever-deepening cascade of statistical methods and if you are going to be up to date you will have to use and cite some of them in your research reports or thesis. But before you jump into these methods, you might consider a few tidbits of advice. I suggest three rules and a few simple guidelines:

Rule 1. For descriptive papers keep to descriptive statistics. Every good basic statistics book has advice on when to use means to describe “average values”, when to use medians, or percentiles. Follow their advice and do not in your report generate any hypotheses except in the discussion. And follow the simple advice of statisticians not to generate and then test a hypothesis with the same set of data. Descriptive papers are most valuable. They can lead us to speculations and suggest hypotheses and explanations, but they do not lead us to strong inference.

Rule 2. For explanatory papers, the statistical rules become more complicated. For scientific explanation you need 2 or more alternative hypotheses that make different, non-overlapping predictions. The predictions must involve biological or physical mechanisms. Correlations alone are not mechanisms. They may help to lead you to a mechanism, but the key is that the mechanism must involve a cause and an effect. A correlation of a decline in whale numbers with a decline in sunspot numbers may be interesting but only if you can tie this correlation into an actual mechanism that affects birth or death rates of the whales.

Rule 3. For experimental papers you have access to a large variety of books and papers on experimental design. You must have a control or unmanipulated group, or for a comparative experiment a group A with treatment X, and a group B with treatment Y. There are many rules in the writings of experimental design that give good guidance (e.g. Anderson 2008; Eberhardt 2003; Johnson 2002; Shadish et al. 2002; Underwood 1990).

For all these ecology papers, consider the best of the recent statistical admonitions. Use statistics to enlighten not to obfuscate the reader. Use graphics to illustrate major results. Avoid p-values (Anderson et al. 2000; Ioannidis 2019a, 2019b). Measure effect sizes for different treatments (Nakagawa and Cuthill 2007). Add to these general admonitions the conventional rules of paper or report submission – do not argue with the editor, argue a small amount with the reviewers (none are perfect), and put your main messages in the abstract. And remember that it is possible there was some interesting research done before the year 2000.

Anderson, D.R. (2008) ‘Model Based Inference in the Life Sciences: A Primer on Evidence.’ (Springer: New York.). 184 pp.

Anderson, D.R., Burnham, K.P., and Thompson, W.L. (2000). Null hypothesis testing: problems, prevalence, and an alternative. Journal of Wildlife Management 64, 912-923.

Eberhardt, L.L. (2003). What should we do about hypothesis testing? Journal of Wildlife Management 67, 241-247.

Ioannidis, J.P.A. (2019a). Options for publishing research without any P-values. European Heart Journal 40, 2555-2556. doi: 10.1093/eurheartj/ehz556.

Ioannidis, J. P. A. (2019b). What have we (not) learnt from millions of scientific papers with P values? American Statistician 73, 20-25. doi: 10.1080/00031305.2018.1447512.

Johnson, D.H. (2002). The importance of replication in wildlife research. Journal of Wildlife Management 66, 919-932.

Nakagawa, S. and Cuthill, I.C. (2007). Effect size, confidence interval and statistical significance: a practical guide for biologists. Biological Reviews 82, 591-605. doi: 10.1111/j.1469-185X.2007.00027.x.

Shadish, W.R, Cook, T.D., and Campbell, D.T. (2002) ‘Experimental and Quasi-Experimental Designs for Generalized Causal Inference.’ (Houghton Mifflin Company: New York.)

Underwood, A. J. (1990). Experiments in ecology and management: Their logics, functions and interpretations. Australian Journal of Ecology 15, 365-389.

On Three Kinds of Ecology Papers

Leave a reply

There are many possible types of papers that discuss ecology, and in particular I want to deal only with empirical studies that deal with terrestrial and aquatic populations, communities, or ecosystems. I will not discuss here theoretical studies or modelling studies. I suggest it is possible to classify papers in ecological science journals that deal with field studies into three categories which I will call Descriptive Ecology, Explanatory Ecology, and Experimental Ecology. Papers in all these categories deal with a description of some aspects of the ecological world and how it works but they differ in their scientific impact.

Descriptive Ecology publications are essential to ecological science because they present some details of the natural history of an ecological population or community that is vital to our growing understanding of the biota of the Earth. There is much literature in this group, and ecologists all have piles of books on the local natural history of birds, moths, turtles, and large mammals, to mention only a few. Fauna and flora compilations pull much of this information together to guide beginning students and the interested public in increased knowledge of local fauna and flora. These publications are extremely valuable because they form the natural history basis of our science, and greatly outnumber the other two categories of papers. The importance of this information has been a continuous message of ecologists over many years (e.g. Bartholomew 1986; Dayton 2003; Travis 2020).

The scientific journals that professional ecologists read are mostly concerned with papers that can be classified as Explanatory Ecology and Experimental Ecology. In a broad sense these two categories can be described as providing a good story to tie together and thus explain the known facts of natural history or alternatively to define a set of hypotheses that provide alternative explanations for these facts and then to test these hypotheses experimentally. Rigorous ecology like all good science proceeds from the explanatory phase to the experimental phase. Good natural history provides several possible explanations for ecological events but does not stop there. If a particular bird population is declining, we need first to make a guess from natural history if this decline might be from disease, habitat loss, or predation. But to proceed to successful management of this conservation problem, we need studies that distinguish the cause(s) of our ecological problems, as recognized by Caughley (1994) and emphasized by Hone et al. (2018). Consequently the flow in all the sciences is from descriptive studies to explanatory ideas to experimental validation. Without experimental validation ‘ecological ideas’ can transform into ‘ecological opinions’ to the detriment of our science. This is not a new view of scientific method (Popper 1963) but it does need to be repeated (Betini et al. 2017). 

If I repeat this too much, I suggest you do a survey of how often ecological papers in your favorite journal are published without ever using the word ‘hypothesis’ or ‘experiment’. A historical survey of these or similar words would be a worthwhile endeavour for an honours or M.Sc. student in any one of the ecological subdisciplines. The favourite explanation offered in many current papers is climate change, a particularly difficult hypothesis to test because, if it is specified vaguely enough, it is impossible to test experimentally. Telling interesting stories should not be confused with rigorous experimental ecology.

Bartholomew, G. A. (1986). The role of natural history in comtemporary biology. BioScience 36, 324-329. doi: 10.2307/1310237

Betini, G.S., Avgar, T., and Fryxell, John M. (2017). Why are we not evaluating multiple competing hypotheses in ecology and evolution? Royal Society Open Science 4, 160756. doi: 10.1098/rsos.160756.

Caughley, G. (1994). Directions in conservation biology. Journal of Animal Ecology 63, 215-244. doi: 10.2307/5542

Dayton, P.K. (2003). The importance of the natural sciences to conservation. American Naturalist 162, 1-13. doi: 10.1086/376572

Hone, J., Drake, Alistair, and Krebs, C.J. (2018). Evaluating wildlife management by using principles of applied ecology: case studies and implications. Wildlife Research 45, 436-445. doi: 10.1071/WR18006.

Popper, K. R. (1963) ‘Conjectures and Refutations: The Growth of Scientific Knowledge.’ (Routledge and Kegan Paul: London.)

Travis, Joseph (2020). Where is natural history in ecological, evolutionary, and behavioral science? American Naturalist 196, 1-8. doi: 10.1086/708765.

On Declining Bird Populations

2 Replies

The conservation literature and the media are alive with cries of declining bird populations around the world (Rosenberg et al. 2019). Birds are well liked by people, and an important part of our environment so they garner a lot of attention when the cry goes out that all is not well. The problems from a scientific perspective is what evidence is required to “cry wolf’. There are many different opinions on what data provide reliable evidence. There is a splendid critique of the Rosenberg et al paper by Brian McGill that you should read::
https://dynamicecology.wordpress.com/2019/09/20/did-north-america-really-lose-3-billion-birds-what-does-it-mean/

My object here is to add a comment from the viewpoint of population ecology. It might be useful for bird ecologists to have a brief overview of what ecological evidence is required to decide that a bird population or a bird species or a whole group of birds is threatened or endangered. One simple way to make this decision is with a verbal flow chart and I offer here one example of how to proceed.

  1. Get accurate and precise data on the populations of interest. If you claim a population is declining or endangered, you need to define the population and know its abundance over a reasonable time period.

Note that this is already a nearly impossible demand. For birds that are continuously resident it is possible to census them well. Let me guess that continuous residency occurs in at most 5% or fewer of the birds of the world. The other birds we would like to protect are global or local migrants or move unpredictably in search of food resources, so it is difficult to define a population and determine if the population as a whole is rising or falling. Compounding all this are the truly rare bird species that are difficult to census like all rare species. Dorey and Walker (2018) examine these concerns for Canada.

The next problem is what is a reasonable time period for the census data. The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) gives 10 years or 3 generations, whichever is longer (see web link below). So now we need to know the generation time of the species of concern. We can make a guess at generation time but let us stick with 10 years for the moment. For how many bird species in Canada do we have 10 years of accurate population estimates?

  • Next, we need to determine the causes of the decline if we wish to instigate management actions. Populations decline because of a falling reproductive rate, increasing death rate, or higher emigration rates. There are very few birds for which we have 10 years of diagnosis for the causes of changes in these vital rates. Strong conclusions should not rest on weak data.

The absence of much of these required data force conservation biologists to guess about what is driving numbers down, knowing only that population numbers are falling. Typically, many things are happening over the 10 years of assessment – climate is changing, habitats are being lost or gained, invasive species are spreading, new toxic chemical are being used for pest control, diseases are appearing, the list is long. We have little time or money to determine the critical limiting factors. We can only make a guess.

  • At this stage we must specify an action plan to recommend management actions for the recovery of the declining bird population. Management actions are limited. We cannot in the short term alter climate. Regulating toxic chemical use in agriculture takes years. In a few cases we can set aside more habitat as a generalized solution for all declining birds. We have difficulty controlling invasive species, and some invasive species might be native species expanding their geographic range (e.g. Bodine and Capaldi 2017, Thibault et al. 2018).

Conservation ecologists are now up against the wall because all management actions that are recommended will cost money and will face potential opposition from some people. Success is not guaranteed because most of the data available are inadequate. Medical doctors face the same problem with rare diseases and uncertain treatments when deciding how to treat patients with no certainty of success.

In my opinion the data on which the present concern over bird losses is too poor to justify the hyper-publicity about declining birds. I realize most conservation biologists will disagree but that is why I think we need to lift our game by having a more rigorous set of data rules for categories of concern in conservation. A more balanced tone of concern may be more useful in gathering public support for management efforts. Stanton et al. (2018) provide a good example for farmland birds. Overuse of the word ‘extinction’ is counterproductive in my opinion. Trying to provide better data is highly desirable so that conservation papers do not always end with the statement ‘but detailed mechanistic studies are lacking’. Pleas for declining populations ought to be balanced by recommendations for solutions to the problem. Local solutions are most useful, global solutions are critical in the long run but given current global governance are too much fairy tales.

Bodine, E.N. and Capaldi, A. (2017). Can culling Barred Owls save a declining Northern Spotted Owl population? Natural Resource Modeling 30, e12131. doi: 10.1111/nrm.12131.

Dorey, K. and Walker, T.R. (2018). Limitations of threatened species lists in Canada: A federal and provincial perspective. Biological Conservation 217, 259-268. doi: 10.1016/j.biocon.2017.11.018.

Rosenberg, K.V., et al. (2019). Decline of the North American avifauna. Science 366, 120-124. doi: 10.1126/science.aaw1313.

Stanton, R.L., Morrissey, C.A., and Clark, R.G. (2018). Analysis of trends and agricultural drivers of farmland bird declines in North America: A review. Agriculture, Ecosystems & Environment 254, 244-254. doi: 10.1016/j.agee.2017.11.028.

Thibault, M., et al. (2018). The invasive Red-vented bulbul (Pycnonotus cafer) outcompetes native birds in a tropical biodiversity hotspot. PLoS ONE 13, e0192249. doi: 10.1371/journal.pone.0192249.

http://cosewic.ca/index.php/en-ca/assessment-process/wildlife-species-assessment-process-categories-guidelines/quantitative-criteria

On Fires in Australia

2 Replies

The fires of Australia in their summer 2019-20 are in the news constantly, partly because the media survive on death and destruction and partly because to date we have never seen a whole continent burn up. It is hardly a ‘Welcome to the Anthropocene”  kind of event to celebrate, and the northern media display the fires as nearly all news of the Southern Hemisphere is treated, something unusual, often bad, but of no general importance to the real world of the Northern Hemisphere.

What do we hear from a cacophony of public opinion?

“Nothing unusual. We have always had fires in the past. Why in 1863…..”
“Nothing to do with climate change. Climate has always been changing….(see point 1)
“Main cause had been Green Policies. If we had more forestry, there would have been many fewer trees to burn….”
“Inadequate controlled burning because of the Greens’ policies….(see point 3)
“Why doesn’t the Government do something about this?”
“Fortunately these fires are a rare event and not likely to occur again…….

In reply an ecologist might offer these facts:

  1. Much research by plant geographers and ecologists have shown how many plant communities are dominated by fire. The boreal forest is one, the chaparral of Southern California is another, the grasslands of Africa and the Great Plains of the USA are yet more.
  2. By preventing fire in these communities over time the fuel load builds up so that, should there be a subsequent fire, the fire severity would be very high.
  3. By building houses, towns, and cities in these plant communities fire danger increases, and an active plan of fire management must be implemented. Most of these plans are effective for normal fires but for extreme conditions no fire management plan is effective.
  4. Climate change is now producing extreme conditions that were once very rare but are now commonly achieved. With no rainfall, high winds, and temperatures over 40-45ºC fires cannot be contained. Severe fires generate their own weather that accelerates fire spread with embers being blown kilometers ahead of the active fire front.
  5. The long-term plan to have controlled patch burns to relieve these fire conditions are impossible to implement because they require no wind, low temperatures, and considerable person-power to prevent controlled burns getting away from containment lines should the weather change.

Since a sizeable fraction of dangerous fires are deliberately set by humans, methods to detect and prevent this behaviour could help in some cases. Infrastructure such as power lines could be upgraded to reduce the likelihood of falling power poles and lines shorting out. All this will cost money, and the less the fire frequency, the fewer the people willing to pay more taxes to reduce public risk. Some serious thinking is needed now because Australia 2020 is just the start of a century of fire, drought, floods, and high winds. We do not need the politicians of 2050 telling us “why didn’t someone warn us?

There is a very large literature on fire in human landscapes (e.g. Gibbons et al. 2012), and I include only a few references here. They illustrate that the landscape effects of fire are multiple and area specific. Much more field research is needed, and landscape ecology has a vital role to play in understanding and managing the interface of humans and fire.

Badia, A. et al. (2019). Wildfires in the wildland-urban interface in Catalonia: Vulnerability analysis based on land use and land cover change. Science of The Total Environment 673, 184-196. doi: 10.1016/j.scitotenv.2019.04.012.

Gibbons, P, et. al. (2012) Land management practices associated with house loss in wildfires. PLoS ONE 7(1): e29212. https://doi.org/10.1371/journal.pone.0029212

Gustafsson, L. et al. (2019). Rapid ecological response and intensified knowledge accumulation following a north European mega-fire. Scandinavian Journal of Forest Research 34, 234-253. doi: 10.1080/02827581.2019.1603323.

Minor, J. and Boyce, G.A. (2018). Smokey Bear and the pyropolitics of United States forest governance. Political Geography 62, 79-93. doi: 10.1016/j.polgeo.2017.10.005.

Ramage, B.S., O’Hara, K.L., and Caldwell, B.T. (2010). The role of fire in the competitive dynamics of coast redwood forests. Ecosphere 1(6), art20. doi: 10.1890/ES10-00134.1.

Thoughts on Wildlife Management

Leave a reply

Stop for a moment and think about where we are now in the science of wildlife management and conservation. Look at the titles of paper in our scientific journals. The vast majority of the problems and questions being investigated are basically about how to reverse some human-caused folly. Many wildlife scientists, ecologists, and organismal biologists entered science with the goal of understanding natural systems from the ecosystem down to the molecular level but in the past 60 years the focus has had to shift. This shift has occurred almost unnoticed because it has been gradual in the time scale of human employment and turnover. The ecosystems of the world are in a frightful mess, and virtually all the mess is human caused. So while we engage in many discussions about how to define the ‘Anthropocene’ in the geological sciences (Correia et al. 2018; Zalasiewicz et al. 2017) ecological science is left in the dust because it never leads to ‘progress’.

This came home to me when I considered which of the many study sites in which classical ecological research has been carried out over the last century still exist. They have been replaced by suburbs, highways, shopping malls, farms, and industrial sites, and the associated waterways have been altered beyond recognition. A simple consequence is that if you wished to repeat a famous ecological study done 50-100 years ago, you could not do it because the site has been obliterated. One consequence is that if we wish to do field work today, we choose a new site that has so far been protected from development.

The elephant in the room now is climate change, so if you choose to investigate the trophic dynamics of an Amazonian forest area (for example), you face two problems – the site could be obliterated by ‘development’ before your work is completed, or the climate changes expected during the next 80 years will alter the trophic dynamics of your site so that your current results are no guide to the future state of these ecosystems. Whither predictive ecology? Many of us thought that by discovering and analyzing ecological principles, we could closely approach the precision of the physical sciences, the laws of physics and chemistry. But the more we search for generality in ecology the less we find. We retreat to general principles that are too vague to be of any predictive use for the wildlife managers of the future.

The thought has been prevalent that by investigating the changes in communities and ecosystems in the past we would have a guide to the future. This belief guides much of paleo-ecological research as well as the projections from evolutionary research of how species have recovered from the recent ice ages. But the past is perhaps not necessarily a good guide to the future when we add in the human footprint arising from the combination of population growth and climate change. Ecologists are left with the concern that our findings have much current value but perhaps little long-term insight. 

Many current papers on ecological changes assume a simple extrapolation predicting the future state of ecosystems (e.g. Martin et al. 2019; Yu et al. 2019). Testing these kinds of extrapolations is virtually possible within the lifetime of the typical ecologist, and my concern is that management actions that are recommended now may be completely off the mark in 30 years. Several papers have warned about this (e.g. Inkpen 2017; La Marca et al. 2019; Mouquet et al. 2015) but as far as I can determine to little effect.

I think the bottom line might be a recommendation for all predictive papers to state a strong prediction and a defined time frame so that there is hope of testing the predictive model in ecological time. Otherwise we ecologists begin to fall into the realm of science fiction.

Correia, R.A. et al. (2018). Pivotal 20th century contributions to the development of the Anthropocene concept: overview and implications. Current Science 115, 1871-1875. doi: 10.18520/cs/v115/i10/1871-1875.

Inkpen, S.A. (2017). Are humans disturbing conditions in ecology? Biology & Philosophy 32, 51-71. doi: 10.1007/s10539-016-9537-z.

La Marca, W. et al. (2019). The influence of data source and species distribution modelling method on spatial conservation priorities. Diversity & Distributions 25, 1060-1073. doi: 10.1111/ddi.12924.

Martin, D. et al. (2019). Long-distance influence of the Rhône River plume on the marine benthic ecosystem: Integrating descriptive ecology and predictive modelling. Science of The Total Environment 673, 790-809. doi: 10.1016/j.scitotenv.2019.04.010.

Mouquet, N. et al. (2015). Predictive ecology in a changing world. Journal of Applied Ecology 52, 1293-1310. doi: 10.1111/1365-2664.12482.

Yu, F., et al. (2019). Climate and land use changes will degrade the distribution of Rhododendrons in China. Science of The Total Environment 659, 515-528. doi: 10.1016/j.scitotenv.2018.12.223.

Zalasiewicz, J. et al. (2017). The Working Group on the Anthropocene: Summary of evidence and interim recommendations. Anthropocene 19, 55-60. doi: 10.1016/j.ancene.2017.09.001.