A positive outlook on large carnivores in Europe
There was a popular saying when I was working as a research biochemist in the 1980s that you needed a wheel barrow to haul around the sheer volume of your published papers as evidence of academic success. I never got caught up in that career grind of publishing anything and everything, and so the saying did not apply to my meagre output. Being on the other side as well, as a reviewer of submitted articles to various journals, I never accepted a poor paper for publication, but there seemed quite a few at that time that were published, seemingly being evidence of a complicity to support fellow colleagues in playing the game. Perhaps I am being too harsh, but letting poor papers through that just add another tick to someone’s accumulative list, degrades the integrity of academic publishing. Just as bad is the situation where a paper is published that seeks to diminish the importance of a particular process in an attempt to aggrandise their own findings, and which trashes the reputation of a dead person in doing so.
Using unreliable data
I came across an example of the latter when I
delved behind why, on coming back to re-read Paul Colinvaux’s popular account
of ecology from 1980 (1) he appeared to discount Charles Darwin’s descriptions
of the “struggle for existence” (2); that “animals and plants in
nature are not after all engaged in debilitating struggle, as a loose reading
of Darwin might suggest”; that only a “careless reading of Darwin”
made inevitable a trophic process of predator-prey interaction; and that
survival of the fittest was a “deformed view of what Darwin wrote”. We
get to the nub of Colinvaux’s bone of contention when he says “It seems
very likely that the larger and fiercer predators are not nearly so important
in regulating the numbers of animals in nature as common sense suggests”.
While Colinvaux appears to be blaming us for misinterpreting what Darwin
meant, rather than blaming Darwin himself, he was more explicit in his
anti-predator crusade in fingering Aldo Leopold. In his suggestions for
further reading, Colinvaux makes this accusation:
In justification, Colinvaux invoked a paper by
New Zealand ecologist Graeme Caughley published in 1970 in the journal Ecology
that needlessly and meretriciously trashed the reputation of Aldo Leopold (3).
Caughley accused Leopold of using unreliable data in his paper from 1943 on
the irruption of deer in a Game Preserve on the Kaibab Plateau in Arizona in
the 1920s (4). Leopold had sought to show a causal link between the irruption
of deer and a local policy of removal of predators, such as wolves and
mountain lions. Since Leopold had relied on the data of Irvin Rasmussen from
1941 (5) Caughley also trashed him. It is a wonder that Caughley didn’t also
trash Oxford ecologist Charles Elton. I have noted before that Elton’s seminal
book on Animal Ecology from 1927, although not specifically naming the Grand
Canyon National Game Preserve on Arizona's Kaibab Platea, described the
consequences of the removal of the predators from the Plateau as a booming
population of deer (6,7):
It is the case that Elton and Leopold met up at the Matamek Conference on Biological Cycles, held at the Matamek Factory at the mouth of the Matamek River as it flows from the north shore into the St Lawrence River, east of Sept Isle in Quebec, Canada (8,9). The conference was about fluctuations in populations of such species as trees, insects, sea and river fish, game birds, birds of prey, mice, rabbits and a range of “fur-bearing animals that prey upon their smaller neighbors. They also occur in the bacteria and other parasites which cause epidemics among animals and sweep them away by the millions” (10). Leopold described to the Conference a cycle of nine or ten years among the grouse and rabbits of Wisconsin and neighbouring lake states, whereas Elton described a four year cycle in “far northern mice, lemmings and Arctic ptarmigan, and also in the Arctic fox and snowy owl which feed upon these lesser types of animals”. The two men corresponded thereafter, but I should point out that this conference took place in 1931 and thus after Elton had written his book, as did Leopold’s paper on deer irruptions. Elton would therefore not have been influenced by Leopold in his understanding of events at Kaibab in his book, even though they came to the same conclusion, but Leopold’s writings were to show thereafter a greater focus on the functional concepts of ecology, as synthesised in Elton’s book (9)
I have explained elsewhere that the reason Caughley took the approach of denigrating Leopold was so that he could then substantiate the ecological validity of his own study on the irruption in New Zealand of the non-native Himalayan tahr, an invasive goat-like bovid, as it fitted his results that the rate of increase of the tahr population was influenced only by food supply, there being no natural predator of the tahr in New Zealand (11). That Caughley had sought to portray his observations on the population variation of a feral herbivore as having significance for eruptive fluctuations in other species, was of course an ecological nonsense, since why would it have any relevance when he was observing an artefact of human construction from the introduction of this non-native animal, not subject to predation, to New Zealand? It would be 46 years, 68 years after Leopold’s death, for Caughley to be shown for the hypocrite he was in having himself misused data, as well as an investigation of the variation in the age range and regeneration of aspen on the Kaibab Plateau showing a temporal link with the removal of predators and the irruption of deer (12).
What I didn’t mention in that explanation was that after Caughley’s critique, textbooks on ecology apparently began to purge references to the Kaibab deer as an example of predator-prey interaction, and the story of the Kaibab Plateau was called a “cherished fable” and a “long persisting myth”, but that the existence of the myth had a cautionary value about accepting “faulty examples and spurious interpretations of dubious facts”(13). Well, I use this whole example as a learning point for students on the wilderness course at Leeds to check whether it has stood the test of time and any re-examinations before they use a paper like Caughley’s for a defining argument. It does beg the question why Caughley’s paper was accepted anyway for publication.
Pontificating on wolves
I have noted before that the Dutch herbivorists
have a lot in common with Caughley in denying or minimizing the influence that
carnivores have on the behaviour and impact of herbivores (14). Thus in a
guide to using domestic livestock as “landscape architects” produced by
Free Nature and Eurosite (co-founders of "Rewilding" Europe) diminishes the
role of predators' and behaviourally mediated
effects don't exist (15):
However, it is not just the Dutch herbivorists, but also their fellow travellers in the European megaherbivore mafia. I have written before about my correspondence with Paul Jepson, and how he admitted that he had been focusing on herbivores and “upward cascades”, rather than herbivores and predators, as part of his “rewilding package” (16). However, he could not let that admission rest without seeming to justify it. He had sent me three papers, two of his own and one by David Mech, the latter author having a history of pontificating on wolves, such as claiming an existence of alpha males in wolf behaviour, and then recanting the existence of them later on (17-19). In the Mech paper Jepson had sent me, Mech claimed that scientists, wolf advocates and the news media alike were painting an overly positive image of the wolf in the ecological restoration of Yellowstone, giving the fact that later research had challenged several previous studies’ findings such that earlier conclusions on the influence of wolves in fostering the regrowth of woody vegetation by influencing deer herbivory were now controversial – “The wolf is neither a saint nor a sinner except to those who want to make it so” (20)
Well, as I have explained, the discrepancies have probably arisen because different studies have measured different things (average aspen sucker heights compared to tallest five sucker heights) and in different places (riparian, non-riparian) or have had too many variables (willow, water, elk, wolves) and few have had follow up studies that tracked changes as long as possible ((21) and see (22)). The latter is a key factor since wolves have only been back in Yellowstone since 1995, and so most studies of effects have only had a few years and none are published yet that cover the last five years, giving the potential of at least 20 years rather than the 10 (or even three) years of most studies. Others have tackled Mech over his assertions, in particular about the news media being complicit in promoting positive studies about wolves, pointing to his “reliance upon a biased sample (11 sources, selected purposively, as opposed to randomly)” before citing data of their own that gives a different story (23). When I eventually responded to Jepson, I explained that the delay was because I was researching whether there was any credible evidence that the ecological role of wolves could be substituted by, for instance, fences (21) and where the influence of an opinion like that of Mech could lead to the wrong decision being made. I also said that I always tell our students to check whether there have been any replies/rebuttals before they use a paper for a defining argument, and this was the case with the Mech paper.
Jepson’s use of the Mech paper was in
combination with his own papers when he wanted to illustrate what he called
his engagement with Actor-Network Theory over the last 4-5 years, and his
efforts to apply that to conservation:
I couldn’t find any reference to Transaction
Cost Theory in his two papers (25,26) but I think what he really meant was
Transaction-Cost Analysis since that, along with Social Network Analysis, is
linked to Actor-Network Theory (ANT) in being approaches towards understanding
networks through organisational theory and behaviour (24). In his first paper,
Jepson seeks to define what is a conservation actor, by which he means
individuals, institutions, and collectives that have traditionally delivered
conservation goals in practice, and which he believes are “entities with
agency” in that they have the capacity to “produce a phenomenon or
modify a state of affairs”. (25). He describes ANT as going beyond
associations of humans with agency to consider the “participation of
non-human entities in the assembly, behaviours, and influence of networks”.
It is from drawing on theoretical developments in this aspect of ANT, and of
collective governance, that Jepson concluded that the concept of an actor in
conservation biology “should be broadened to include non-humans, such as
species, because they have the agency and ability to influence project goals
and outcomes” (25):
Drawing again on actor-networks, Jepson’s other
paper proposed a theory about flagship species action, where a flagship
species is one of those popular or iconic species on which there is a focus of
attention for its conservation (26):
My simple intellect finds all this virtually impenetrable, particularly when his example of Asian elephants as a non-human actor merely reflects the consequences of their large spatial requirements; their behavioural response in landscapes of differing levels of human use; and the fact that being a large species poses differing conservation issues compared to say a small rodent. If I thought I knew what Jepson was getting at by referencing Mech’s paper about wolves in relation to wilding, then I didn’t after I had read his papers. Perhaps the "agency" imbued in wolves as a “non-human actor” that is “enrolled in the network” of Yellowstone comes down to wolves thinking about where their next meal is going to come from, and how long it is before the next mating season. I doubt the wolves trouble themselves about whether their existence is contributing indirectly to a burgeoning regeneration of the riparian vegetation in Yellowstone.
The invocation by Jepson of the Mech paper trashing the outcome of wolf reinstatement is reminiscent of those who perennially use Cronon’s polemic to trash wilderness (27). I’ve picked apart Cronon’s nonsense, of how he lays the blame for wilderness being the “wrong nature” on European Romanticism, imported into America in the 19th century (28). Moreover, it is never acknowledged by those who bend Cronon’s article to their purpose, that when it was republished in the journal Environmental History, it was immediately followed by three, varied, detailed and very cogent rebuttals (29-31). More evidence if needed that using a paper for a defining argument needs great care.
Anthropogenic influence on the dynamics of predation is not a novel issue
If I had to say who else from the European megaherbivore mafia would be likely to reference the Mech paper in an anti-predator crusade, then it would be Joris Cromsigt of the Swedish University of Agricultural Sciences (Sveriges lantbruksuniversitet (SLU)) in Umeå. He doesn’t disappoint. Cromsigt is not above advancing an undisclosed personal agenda through the academic literature. This is evidenced by his clumsy attempt to redefine the habitat selection of European bison in justification for the presence of some captive bison on a sand dune in the Netherlands (11) my account of which got me a defensive response in an email from Carl-Gustaf Thulin, a colleague of Cromsigt’s at SLU (32). The ecological consequence of large carnivores in Europe became Cromsigt’s next target for redefinition when he organised a symposium at the annual meeting in February 2015 of Oikos, the Swedish ecological society, held at Umeå University (33). It is obvious in the briefing paper that shaped the symposium that a negative outlook was being pursued since it sought to cast doubt that the pattern of trophic interactions and behaviour between predator, prey and vegetation would be consistent across European landscapes because of the heavy modification by humans (34). It is not unusual in organising a symposium to give invitations to selected speakers (see the briefing) but there is the danger when pursuing a negative rather than a positive outlook that objectivity is cast aside. You can judge whether this occurred as you read on.
Anthropogenic influence on the dynamics of
predation is not a novel issue, since Mech had already noted that most of the
studies in America on trophic interaction had been conducted in National
Parks, areas that are substantially free of the ravages of human exploitation,
whereas the greater part of the wolfs range would be outside of the Parks
(20). Mech had also ventured that the density of wolves outside of Parks would
never reach those inside because he said wolf populations would almost always
be managed outside of National Parks. Mech gave little evidence for his
contentions, completely ignoring the protections given to wolves under the
Endangered Species Act (35,36) and being sweeping in his dismissal of the
impact of wolves (20):
Cromsigt’s symposium took place on Friday, 6 February 2015, between 10.30 -12.30 (Symposia 8 – see (37,38)). I can find no record of the proceedings, but you can imagine his frustration when a few months after the symposium, another group beat him to publication with their own take on the influence of human activities on ecosystem regulation by predators in Europe. This was an interesting study, utilising data on species’ occurrence and encounters from camera traps and hunting records in a human-dominated landscape in Transylvania, Romania, but which is highly diverse, including apex predators (brown bear and wolf ) mesopredators (red fox) and large herbivores (roe and red deer) as well as hunters and their dogs (39). Their aim was to use the data in quantifying through modelling the relative effects of top-down and bottom-up processes in shaping predator and prey distributions. Unsurprisingly, their conclusion was that apex predators maintained their ecological role by suppressing lower trophic levels in a human-dominated landscape, especially the herbivores, but that the combined direct and indirect anthropogenic top-down effects dominated over natural processes. You might think this intuitive. However, Cromsigt exhibited his usual reaction when he finds other groups thinking differently from him by blasting the paper, criticising the methodology that had been employed (40). Perhaps he was irked because one of the authors of the paper that had trumped him was Tobias Kuemmerle, Head of Conservation Biogeography at Humboldt-University in Berlin. He had been the lead author of the paper on the range dynamics and range fragmentation of European bison that Cromsigt had blasted in his clumsy attempt to redefine the habitat selection of European bison (see above).
As Kuemmerle did then, his group replied with a devastating critique of the logic failure of Cromsigt’s blast, explaining that it was incorrect to conclude that no appropriate bottom-up controls were included in their models; that their design did in fact employ a randomized approach to camera placement across the landscape; that it was a tenuous criticism that the top-down and bottom-up processes were not examined at appropriate spatial resolutions because the model allowed the strength of the response of species to predator densities at each scale to be the deciding factor, rather than assuming that predator–prey dynamics occur at a particular scale; that the supplementary information to the paper showed the rank ordering of estimates of wolf densities were consistent through time (from 2006 to 2010) and so were a useful indicator of the relative differences in wolf abundance and activity; and that humans were not included as drivers of wolf distributions because they did not attempt to explain wolf or bear densities obtained for hunting grounds, as they were at a much larger scale than species encounter rates obtained from cameras, or human population size in nearby villages (41). As they say, they did not disregard the possible effects of humans on this in their discussion, but they were unable to examine this linkage effectively because of the different spatial scales that wolves and humans were measured on, as humans were measured at a finer spatial scale.
No new field data
Belatedly, over a year afterwards, Cromsigt finally got around to publishing the outcome of his symposium – it referenced the Mech paper (42). Unlike the paper that had beaten him to publication, Cromsigt’s contained no new field data – it was entirely a desk study, using what others had done to speculate within his own agenda. Basically what Cromsigt and his group (those he had selected for the symposium – see above) wanted to put forward was what they thought were the research priorities in studying the role of carnivores in the anthropogenic landscapes of Europe. You can now see why Cromsigt had criticised the methodology of the paper that had trumped his, the criticism being a pre-emption of what was to come in his own paper, and also presumably because he didn’t like the conclusion that apex predators maintained their ecological role by suppressing lower trophic levels in a human-dominated landscape.
There were only two novel pieces of evidence in Cromsigt’s paper. One was a literature search for papers on trophic cascades, showing the high number of studies coming from North America, and in their National Parks, compared to Europe, Australia and Africa. This finding is used to suggest a bias in the advocacy of carnivore conservation and restoration in Europe in seeing large carnivores as “saviours of biodiversity and ecosystem functioning” largely based on studies coming primarily out of relatively natural landscapes in North American National Parks. The preponderance of papers from North America is hardly surprising, given the longer history of an engagement with the functioning of ecosystems at a large scale, and with the reluctance in Europe (particularly in Britain) to get over the classic cultural obstacle in recognising that there are parallels to be drawn, but which are increasingly being researched in Europe (43,44).
The other piece of evidence is a plotting of published data on the current European wolf distribution compared to a plot of the human footprint index, and a plot of net primary productivity. These three plots together are alleged to show a gradient of anthropogenic effect in which the wolves exist and which could be used to study its impact on the functional role of predators, their distribution, and the abundance and distribution of their prey. I have Steve’s voice in my ear when even I can recognise that there is no attempt to correlate at any spatial scale a quantitative relationship between these variables. Moreover, as we showed in our report to the Scottish Government, the overwhelming characteristic of the distribution of wolves in Europe, as evidenced by the designation of Natura 2000 sites for significant protection of a country’s population, correlated with the most wild areas of the continent, areas with low human footprint and low net primary productivity (45). That this relationship is marginally shifting now with the westward move of wolves into new countries in Europe is only a very recent phenomenon of the last couple of decades, and which does not invalidate the natural dynamics of the existing majority of substantially unfettered wolf population. I would also venture that dietary studies of wolves in Germany, one of the recent new voluntary reinstatements, and which could be considered overall a more anthropogenically modified country, show the wolves to essentially seek out wild mammals and not livestock, an indication that they take the wildness with them wherever they migrate (46). It will also be interesting to see, now that wolves are increasingly migrating into Denmark and the Netherlands, whether the areas in which they settle are those that have been predicted for them in the evaluations from spatial studies based on habitat and prey availability in both countries (7). Given that the criteria in the spatial studies were more likely to have picked out areas with relatively the least human modification and influence, it then becomes a circular argument about whether humans affect predator distribution and thus effect, or if the wolves are just smarter than us in avoiding our influence, and can thus get on and do what they do.
The greatest objection to Cromsigt’s paper are the examples of puerile rhetoric that should not be seen in an academic publication, such as in the title of the paper – “Paws without claws?” – which only seeks to diminish and trivialise large carnivores. Another is the use of the word “saviour” in relation to predators (see above) which is only a subjective value judgement because it is not a direct quote from any of the three references cited in support of the sentence in the paper in which it appeared. Exactly the same can also be said of the use of “romanticize” in this sentence in the Concluding remarks – “It may therefore be important not to romanticize the overall ecological role of large carnivores”. Why did the reviewers of Cromsigt’s paper allow the use of these two words? It is thus patently obvious that Cromsigt’s paper was not born out of intellectual curiosity, but in another attempt to redefine trophic interaction in Europe. So what is he saying – that there is no point in having large carnivores as predators in Europe? It will be no surprise that Cromsigt, having been born in the Netherlands, now works in a country that systematically shoots its wolves, and is subject to infringement proceedings from the European Commission for doing so (47) as well as blasting away at large numbers of moose, thus killing off the wolves prey (48,49)
A positive outlook for lynx reinstatement in Britain
I made a personal commitment to lynx reinstatement in Britain after the stakeholder forum meeting of the Lynx UK Trust last year (16) by becoming a member of the Trust’s Project Stakeholder Forum, a constituted advisory group on the trial reinstatement of Eurasian lynx. There is no attempt by the Trust to necessarily portray the trial as a means of driving wilding through ecological restoration in a large area: there are no assertions that lynx will be the “saviours of biodiversity and ecosystem functioning” in Britain; nor do I see the Trust “romanticize the overall ecological role” of lynx. The only consideration is that there are enough roe deer around for them to eat so that they aren’t tempted to start chomping through any sheep. If you think about it, these lynx are bound to have an ecological effect since every roe deer eaten by them has an impact. Killing roe deer will affect its overall population; the vegetation that would have been eaten by the dead roe deer lasts a little longer; scavengers get to pick over the corpse after the lynx; decomposers start on what’s left; nutrients from decomposition and defecation enter the soil; and the lynx gets to kill again. There has been progress since that stakeholder forum meeting in doing the necessary work in developing applications for the trial release of lynx, and there is an interesting parallel between the Trust’s proposals with the reinstatement of lynx in a transboundary Biosphere Reserve that straddles France and Germany. I will return later to this positive outlook for lynx reinstatement in Britain.
Mark Fisher 14 March 2017
(1) Colinvaux, P.A. (1980) Why Big Fierce Animals are Rare. Penguin Books
(2) Darwin, C. (1859) Chapter 3: Struggle for existence, in On the origin of species, John Murray, London
(3) Caughley, G. (1970). Eruption of ungulate populations, with emphasis on Himalayan thar in New Zealand. Ecology 51: 53-72
(4) Leopold, A. (1943) Deer irruptions. Transactions of the Wisconsin Academy of Sciences, Arts and Letters 35: 351-366
(5) Rasmussen, D.I. (1941) Biotic Communities of Kaibab Plateau, Arizona. Ecological Monographs 11: 229-275
(6) Elton, C. (1927) Animal Ecology. Sidgwick and Jackson, London
(7) Ecological consequence of predator removal, Self-willed land July 2014
(8) Simberloff, D. (2012). Integrity, Stability, and Beauty: Aldo Leopold's Evolving View of Nonnative Species. Environmental History, 17(3), 487-511
(9) Warren, J. L. (2016) Aldo Leopold's Odyssey, Tenth Anniversary Edition: Rediscovering the Author of A Sand County Almanac. Island Press
(10) Huntington, E. (1931). The Matamek conference on biological cycles, 1931. Science, 74(1914), 229-235
(11) Bison habitat preference becomes a pawn in the disputed natural vegetation cover of Europe, Self-willed land November 2015
(12) Binkley, D., Moore, M.M., Romme, W.H. and Brown, P.M. (2006) Was Aldo Leopold Right about the Kaibab Deer Herd? Ecosystems 9: 227–241
(13) Burke, C.J., 1973. The Kaibab deer incident: a long-persisting myth. BioScience 23, 113–114
(14) Dissecting the warped ideology, in What is rewilding?, Self-willed land September 2013
(15) Natural grazing: wild and semi-wild animals as landscape architects. FREE Nature and Eurosite May 2013
(16) One more step towards the trial release of lynx, Self-willed land June 2016
(17) Mech, L. D. (1966) Social ranking within the large pack, In The Wolves of Isle Royale. U.S. National Park Service Fauna Series No. 7.
(18) Mech, L.D. (1970) The wolf: the ecology and behavior of an endangered species. Natural History Press
(19) Mech, L. D. (1999). Alpha status, dominance, and division of labor in wolf packs. Canadian Journal of Zoology, 77(8), 1196-1203
(20) Mech, L. D. (2012). Is science in danger of sanctifying the wolf? Biological Conservation 150(1), 143-149.
(21) Can the ecological functions of wolves be substituted? Self-willed land September 2015
(22) Beschta, R. L., & Ripple, W. J. (2016). Riparian vegetation recovery in Yellowstone: The first two decades after wolf reintroduction. Biological Conservation, 198, 93-103.
(23) Bruskotter, J. T. (2013). To the editor: If science is “sanctifying the wolf” the news media is not complicit. Biological Conservation 158: 420
https://tinyurl.com/hmuhpvy(24) Thompson, G.F. (2003) Social Network Analysis, Transaction-Cost Analysis, and Actor-Network Theory: Three Approaches to Networks. In Between Hierarchies and Markets
(25) Jepson, P., Barua, M., & Buckingham, K. (2011). What is a conservation actor? Conservation and Society 9(3): 229-235
(26) Jepson, P., & Barua, M. (2015). A theory of flagship species action. Conservation and Society 13(1): 95-104
(27) Cronon, W (1996). The Trouble with Wilderness: Or, Getting Back to the Wrong Nature. Environmental History 1: 7-28
(28) Forest, Rocks, Torrents, Self-willed land October 2011
Hays, S.P. (1996) Comment: (29) The Trouble with Bill Cronon's Wilderness. Environmental History 1: 29-32
(30) Cohen, M.P. (1996) Comment: Resistance to Wilderness. Environmental History 1: 33-42
(31) Dunlap, T.R. (1996) Comment: But What Did You Go Out into the Wilderness to See? Environmental History 1: 43-46
(32) Carl-Gustaf, 16 December 2015. Bison habitat preference becomes a pawn in the disputed natural vegetation cover of Europe Your contribution, Self-willed land
(33) OIKOS Meeting 2015, February 4-6, Umeå Sweden
https://tinyurl.com/zgpynvt(34) Carnivore top-down effects in a European landscape of fear: What do we know and where do we go from here? Ellinor Sahlen & Joris Cromsigt
(35) Restoring the gray wolf, Centre for Biological Diversity
(36) Gray wolf (Canis lupus), ECOS Environmental Conservation Online System, U.S. Fish and Wildlife Service
(37) Invited Symposia, OIKOS Meeting 2015
(38) Programme, OIKOS Meeting 2015
(39) Dorresteijn, I., Schultner, J., Nimmo, D.G., Fischer, J., Hanspach, J., Kuemmerle, T., Kehoe, L. and Ritchie, E.G. (2015). Incorporating anthropogenic effects into trophic ecology: predator–prey interactions in a human-dominated landscape. Proc. R. Soc. B 282: 20151602
(40) Kuijper, D. P., Bubnicki, J. W., Churski, M., & Cromsigt, J. P. (2016). Multi-trophic interactions in anthropogenic landscapes: the devil is in the detail. Proc. R. Soc. B 283: 20152375
(41) Ritchie, E.G., Schultner, J., Nimmo, D.G., Fischer, J., Hanspach, J., Kuemmerle, T., Kehoe, L. and Dorresteijn, I. (2016) Crying wolf: limitations of predator–prey studies need not preclude their salient messages. Proc. R. Soc. B 283: 2016124
(42) Kuijper, D. P. J., Sahlén, E., Elmhagen, B., Chamaillé-Jammes, S., Sand, H., Lone, K., & Cromsigt, J. P. G. M. (2016) Paws without claws? Ecological effects of large carnivores in anthropogenic landscapes. Proc. R. Soc. B 283: 20161625
(43) Fisher, M. (2009) Ecological incompleteness and our missing top predators: learning the lessons from abroad. Wilder Horizons 1: 14-16
(44) Fisher, M. (2016) Ecological values of wilderness in Europe. Chapter 3 In Bastmeijer, K. (Ed.). Wilderness Protection in Europe: The Role of International, European and National Law. Cambridge University Press. 67-93
(45) Fisher, M., Carver, S., Kun, Z., McMorran, R., Arrell, K., & Mitchell, G. (2010). Review of status and conservation of wild land in Europe. Report: The Wildland Research Institute, University of Leeds, UK
(46) Wagner, C., Holzapfel, M., Kluth, G., Reinhardt, I., & Ansorge, H. (2012). Wolf (Canis lupus) feeding habits during the first eight years of its occurrence in Germany. Mammalian Biology-Zeitschrift für Säugetierkunde, 77(3): 196-203
(47) Giving natural justice to wild nature, Self-willed land January 2017
(48) Wikenros, C., Sand, H., Bergström, R., Liberg, O., & Chapron, G. (2015). Response of moose hunters to predation following wolf return in Sweden. PloS one, 10(4), e0119957. http://journals.plos.org/plosone/article/file?id=10.1371/journal.pone.0119957&type=printable
(49) Wikenros, C., Balogh, G., Sand, H., Nicholson, K. L., & Månsson, J. (2016). Mobility of moose—comparing the effects of wolf predation risk, reproductive status, and seasonality. Ecology and Evolution, 6(24): 8870-8880