Assisted Migration (Assisted Colonization, Managed Relocation)
and Rewilding of Plants and Animals
in an Era of Global Warming
EDITOR'S NOTE: This annotated and linked list of online-accessible papers, articles, and news reports on assisted migration (aka: assisted colonization / colonisation, translocation, managed relocation) aims to further professional and popular understanding of both the substance and history of debate and actions regarding one of the most significant developments in conservation biology. This list is continually updated; entries are ordered not by date but (rather casually) in a blended order of academic importance, insight into shifting conservation values, expansive treatment of the debate, and provision of background understanding.
Read the National Science Foundation press release of the above article, where you can also access short VIDEOS of Jessica Hellmann talking about the importance of managed relocation.
To see what is going on in Europe on this topic, see pp 42-43 of Convention on the Conservation of European Wildlife and Natural Habitats: Standing Committee Report of November 2009.
For superb popular coverage of this article and the underlying forest-dieoff phenomenon, read the online report by Jim Robbins dated 15 March 2010: "What's Killing the Great Forests of the American West?".
Note: A letter to TEE journal commenting on the above is "Assisted colonization is a techno-fix" by Ioan Fazey and Joern Fischer.
http://www.csmonitor.com/2005/0830/p08s02-comv.html
Click here for Proposed Standards for Assisted Migration of Plants.
Visit The Rewilding Institute.
In-depth exploration of "the biggest controversy in contemporary conservation science." Engagingly written for both a popular and professional audience, journalist Marinelli draws from her interviews with leading scientists, horticulturalists, and activists to present the core arguments for and against assisted migration. A site visit to an endangered plant breeding facility (the Atlanta Botanical Garden) is paired in the article with Marinelli's eye-witness description of "eco-vigilante" action, when the loose-knit citizens group Torreya Guardians intentionally planted into forested landscapes of mountainous North Carolina 31 seedlings of the highly endangered Florida Torreya — an assisted migration of some 400 miles northward of historically known native habitat.
A lengthy and elegant feature article that explores the human side of the controversy over assisted migration, with Torreya taxifolia providing the focal point, pro and con, and with actions by the citizen group Torreya Guardians stirring the brew. Comments page accessible through the foregoing link to Orion magazine.
ABSTRACT: Managed relocation (MR) has rapidly emerged as a potential intervention strategy in the toolbox of biodiversity management under climate change. Previous authors have suggested that MR (also referred to as assisted colonization, assisted migration, or assisted translocation) could be a last-alternative option after interrogating a linear decision tree. We argue that numerous interacting and value-laden considerations demand a more inclusive strategy for evaluating MR. The pace of modern climate change demands decision making with imperfect information, and tools that elucidate this uncertainty and integrate scientific information and social values are urgently needed. We present a heuristic tool that incorporates both ecological and social criteria in a multidimensional decision-making framework. For visualization purposes, we collapse these criteria into 4 classes that can be depicted in graphical 2-D space. This framework offers a pragmatic approach for summarizing key dimensions of MR: capturing uncertainty in the evaluation criteria, creating transparency in the evaluation process, and recognizing the inherent tradeoffs that different stakeholders bring to evaluation of MR and its alternatives. [Ed. note: This paper is the product of the Managed Relocation Working Group project. Details of three species-specific case studies, including pro and con managed relocation of Florida Torreya, are described in a supplementary pdf. Click the url at the bottom right of page 1 of the pdf of the main paper.]
Content: "Can a tree native to coastal British Columbia, given climate change, flourish in Fort Nelson? Can a tree native to the Interior live prosperously on Vancouver Island? Those are questions Greg O'Neill hopes to find answers for. O'Neill is a geneticist with Vernon's Kalamalka Forestry Centre, and is overseeing forestry's biggest climate change research trial in North America." Note: O'Neill and other foresters in British Columbia may be the furthest along of anyone in terms of already doing assisted migration of plants and on a massive scale, though it is mostly at the level of reseeding logged lands with seedstock drawn from populations of the same species lower in altitude or latitude.
What O'Neill and colleagues are doing in British Columbia can be learned in the most detail in this article published in the scientific journal Nature on 18 June 2009. You can access the PDF here: "Forestry: Planting the Forest of the Future". See also a transcript of a Canadian television documentary on O'Neil's work with assisted migration for British Columbia forest tree species.
Meanwhile, in the USA, a US Forest Service report, 2009 Science Accomplishments of the Pacific Northwest Research Station includes this: "To test the viability of assisted migration, researchers planted seedlings from locations
throughout western Oregon and Washington and northern California at nine sites in western Oregon and Washington. Responses of the different seed sources will be evaluated relative to test site environments and the environments of the seed sources." Page 49 of Part 2 PDF
Also see a cautionary comment published in BC Forest Professonal, which includes "Growing taller and being more resistant to two diseases in three years does not mean that one population is better adapted to an environment than another. What will happen during the rest of the cottonwood clones' lifetimes? There could be an unseasonal frost or a pathogen that is adapted to attacking mature black cottonwood, killing a large proportion of the assisted southern population, while these trees focus their energy budget on growth at the cost of decreased defenses."
Also see a 2009 article, "Genetic Options for Adapting
Forests to Climate Change", by Brad St. Clare and Glenn Howe (USFS), published in the Jan/Feb 2009 issue of Western Forester.
"IUCN has requested a review and update of its policies on this topic, with the aim of having a comprehensive IUCN position for submission at the 2012 World Conservation Congress. Accordingly the SSC has established the RSG-ISSG Task Force on Moving Species for Conservation Purposes. The lead person in this task force is Mark Stanley Price. Mark will convene a working group to discuss that scale, scope and terminology around this initiative and to gather answers to the questions: (1) How, where and for what do the benefits and risks of assisted colonization or conservation introduction compare favorably to doing nothing to assist species vulnerable to extinction? (2) What taxa of plants and animals do participants feel are the best bet for assisted colonization? and
(3) What should be done to test some hypotheses?
Focal species is the reintroduction of extirpated Oryx to its homeland in Oman and how that will be affected soon by the scheduled release in 2012 of international guidelines for translocation of species in response to climate change by the "Species Survival Commission." Quotes fr Dr Mark Stanley Price, incl: ""That is why chosen scientists from all over the world have been asked by the International Union for the Conservation of Nature and Natural Resources (IUCN), to set up a group to look at assisted colonisation globally. It wants us to set up guidelines for assisted animal colonisation and release new guidelines at the World Conservation Congress in 2012 in South Korea."
Report of 25 May 2009 multi-author paper in Proceedings of the National Academy of Sciences, which proposes a new management tool for choosing which species are most viable for relocation based on a series of social and ecological criteria—for example, how much is known about the biology, geographical distribution and the ecological uniqueness of the species, as well as how easy they are to catch and move. Social factors, such as cultural importance, financial impact and even the laws and regulations regarding the species, also are considered. Partially funded by the National Science Foundation (NSF), the working group is co-led by Jessica Hellmann and Jason McLachlan of the University of Notre Dame, Dov Sax of Brown University, and Mark Schwartz of the University of California at Davis. David Richardson of Stellenbosch University in South Africa led the writing of the paper. See also this Press Release on the paper.
Arresting article on the extent and speed of the paradigm shift in conservation away from traditional "preservation" modes of intervention in behalf of biodiversity to "adaptationist" modes, including the growing acceptance of "assisted migration" as a management tool to cope with globally and regionally shifting climates. Superb coverage of the wrenching change of heart (and financial focus) for conservation programs rooted in "restoration" to practically address the irreversible shifts in climate now inarguably underway. "Managed retreat" (term used by conservation biologist Reed Noss, who argues for an overhaul of Everglades restoration policy) now joins "assisted migration" in the growing panoply of conservation terms and tools.
Note: Serious students of this topic may wish to start with the paper by Shirey and Lambert (below),
as it is an excellent summary of the ecological science, the actions-to-date, the law, and the regulatory options, and it was clearly written from an objective position, neither pro nor con.
"The paper represents a call to arms or a call to caution, depending on your perspective," says Gary Lamberti, the chair of the Department of Biological Sciences who is Shirey's advisor and co-author of the article. "When we're thinking about moving organisms around because of climate change or other environmental factors, we need to think about the legal framework that will enable or not enable us to do that. What Patrick did with his analysis was encourage policy makers and legal scholars to examine the statutes before we reach a crisis point." (quotation drawn from the author's online announcement of the paper). Here are several important legal conclusions made in the paper:
"Current agency regulations
impede alternative strategies such as assisted colonization for endangered animals, but do not impede assisted colonization of endangered plants." (p. 3) "On its surface, the statutory language of the ESA appears to provide the legal framework for allowing assisted colonization of endangered populations to new habitats primarily
under Section 10(j), the experimental population provision" (p. 3) "In 1982 additions to the ESA, Congress sought to restrict
the use of the experimental population provision as a
means of removing protection from species and thus imposed
procedural limits. Those limits, however, did not
restrict the power of the agency to release species into
suitable areas without considering historical distribution.
The USFWS can authorize release outside the current
range if 'release will further the conservation of such
species' (citation). However, in promulgating
regulations to implement the experimental population
provisions, the USFWS added a geographic restriction
in 1984 that prohibits an experimental population
from being introduced outside the historic range, 'absent
a finding. . . in the extreme case that the primary habitat
of the species has been unsuitably and irreversibly altered
or destroyed' (citation) (p. 5) "Perhaps the most successful case of assisted colonization
of a plant listed under the ESA is the Virginia roundleaf
birch (Betula uber). The first translocation of roundleaf
birch occurred after the species was rediscovered in
1975 as a population of 41 trees (59 FR 59173). After
the round-leaf birch was listed in 1978, the USFWS
encouraged its distribution to conservation organizations
and individuals (59 FR 59173). Despite protection of its
habitat by agencies and landowners, the natural population
of round-leaf birch declined to eight trees in 2003
(www.fws.gov/northeast/pdf/vabirch.pdf). However, because
assisted colonization established 20 populations on
U.S. Forest Service land, the USFWS reclassified roundleaf
birch from endangered to threatened in 1994 (59 FR
59173)." (p. 6) "Regulatory restrictions placed on assisted colonization
might be lesser obstacles to overcome than political and
scientific resistance. Political opposition can include concern
over costs of managing populations, resistance of
landowners and local governments to introducing endangered
species, and concern over species invasiveness. The
threat of invasive species, in particular, raises legitimate
scientific concern about assisted colonization." (p. 6) "Assisted colonization could be a viable management
option to offset the human-caused and inseparable problems
of habitat fragmentation and rapid climate change." (p. 7)
Excerpt: Perhaps the most radical update on the table now is the concept of 'assisted migration', a benign phrase that just might be the key to keeping many trees, shrubs and flowers in the landscape — and out of the chilled filing cabinets. But it is a concept that also raises as many problems as it proposes to lay to rest. As with animals, plants migrate to find the best living conditions, but plants do it slowly, over generations. Trees, with their very long life spans, are especially slow. Earthworms are sprinters by comparison. Ten thousand years ago, as the ice sheets retreated from the North American Midwest, trees migrated up the continent at the rate of about 100km per century, until the global climate settled into relative stability — the condition we thought of as normal until very recently. Global change models suggest that climate 'envelopes' will soon be moving north at speeds of 1,000km per century. So, if the models are right, this is a race that trees are certain to lose. . . Donnelly knows that the best outcome of assisted migration will involve the disintegration of cherished and valuable communities of plants and animals. Whatever novel communities will emerge may be poorer, or even richer, in biodiversity than what we know today, but they will certainly be different. However, he argues soberly that assisted migration must be among our options for "managing long-lived trees for an uncertain future". Restoration used to be about attempting to return ecosystems to a past (and more biodiverse) state, but the wild card of climate-change is pushing restoration science towards the creation of new systems, with the proviso that maintaining biodiversity is still the target.
Excerpt from abstract: "Here we present the first global assessment of recent tree mortality attributed to drought and heat stress. Although episodic mortality occurs in the absence of climate change, studies compiled here suggest that at least some of the world's forested ecosystems already may be responding to climate change and raise concern that forests may become increasingly vulnerable to higher background tree mortality rates and die-off in response to future warming and drought, even in environments that are not normally considered water-limited. This further suggests risks to ecosystem services, including the loss of sequestered forest carbon and associated atmospheric feedbacks."
Highly useful integrative paper geared for managers of natural lands that examines the need for new philosophical and practical perspectives on management of parks and wilderness areas today, especially given rapid climate change. "Assisted migration" is discussed in this report, but in the much wider context, thus making this paper a key reading for background perspective as well as precise philosophical and management options that supplement the criterion of "natural" with more precise understandings of "historical fidelity," biodiversity conservation," "resilience," and "ecological integrity."
Torreya Guardians founder Connie Barlow contributed a chapter on the importance of a "deep time" perspective for conservation biologists and biodiversity activists coming to grips with the extinction crisis in an age of rapid climate change. The plight of Torreya taxifolia and the work of Torreya Guardians are used as the key example of "Assisted Migration in a Time of Global Warming".
Conservation biologist Camille Parmeson is profiled in her advocacy for translocation of species threatened by climate change. She is quoted, "It doesn't make any sense to say it's OK for the shipping industry and the transport industry to accidentally move stuff around, for the aquarium trade to move stuff around, for the garden trade to move stuff all over the place, but that it's not OK for a conservation biologist who is desperately trying to save a species from extinction to move it 100 miles. Come on, we have mucked around with Earth to such a degree that I think it's a ridiculous argument.''
"The goal of this study was to compare tree species
compositions in northern urban areas to tree compositions in forestland areas in the eastern U.S. as an
indicator of the potential for urban trees to facilitate future forest tree species migration. Results
indicated that a number of tree species native to eastern U.S. forests of southern latitudes are currently
present in northern urban forests."
"Here, we provide a detailed assessment of the climate sensitivity and potential distributional impacts of 21st century climate change for an illustrative endemic species limited to a restricted part of the Mediterranean region. This region is rich in endemic species and is expected to experience particularly severe global-change-driven biodiversity losses over the 21st century. The study species is the Iberian desman Galemys pyrenaicus (E. Geoffroy Saint Hilaire, 1811), a small semi-aquatic mammal endemic to the Iberian Peninsula.
Abstract. Full text available for online purchase.
12-page report in PDF
The report, a collaboration between the USFWS, the US Geological Survey, academics and a collection of environmental and wildlife groups, quantified the vulnerability of each species on the basis of its breeding behaviour, habitat, migratory pattern and ecological niche. George Wallace, vice-president for oceans and islands at the American Bird Conservancy in The Plains, Virginia, says the report shows that "we need to consider climate change as we continue conservation work into the future".
Whether species that have persisted throughout historic climatic upheavals will survive contemporary climate change will depend on their ecological and physiological traits, their evolutionary potential, and potentially upon the resources that humans commit to prevent their extinction. For those species where temperatures influence sex determination, rapid global warming poses a unique risk of skewed sex ratios and demographic collapse. Here we review the specific mechanisms by which reptiles with temperature-dependent sex determination (TSD) may be imperilled at current rates of warming, and discuss the evidence for and against adaptation via behavioural or physiological means. We propose a scheme for ranking reptiles with TSD according to their vulnerability to rapid global warming, but note that critical data on the lability of the sex determining mechanism and on the heritability of behavioural and threshold traits are unavailable for most species. Nevertheless, we recommend a precautionary approach to management of reptiles identified as being at relatively high risk. In such cases, management should aim to neutralise directional sex ratio biases (e.g. by manipulating incubation temperatures or assisted migration) and promote adaptive processes, possibly by genetic supplementation of populations.
This paper is listed here, as well as among the "rewilding" links at bottom, because while advocating carefully assessed and monitored "taxon substitutions" of tortoises (that is, re-introducing herbivorously similar large and giant tortoises into landscapes, especially islands, where the endemic species were exterminated by humans or shifting sea levels within historic or prehistoric time), the authors also suggest that it would be helpful for the IUCN to include in its current work to develop express international guidelines for managing the need to engage in climate-induced "assisted migration/translocation" guidelines as well for "taxon substitutions": "Despite global potential for resurrecting lost species interactions and restore degraded ecosystem functions, taxon substitutions remain controversial. We suggest that a healthy debate on the applicability of taxon substitutions could be facilitated by including guidelines for them within an
expanded IUCN species translocation framework. This would have the added benefit of promoting species interactions and functional integrity of ecosystems as integral parts of all translocation projects. Furthermore, conducting taxon substitutions and reintroductions within a proper experimental framework will facilitate the interpretation of ecosystem responses
Important scholarly/scientific work that results in an estimate of 1/3 mile per year on average of latitudinal shift in climate and only 8% of protected lands being large enough to include today's climate within its bounds in a century. The abstract only is available for free online, at the url above, but you can read a news report of it at Discovery News.
clip from ABSTRACT: "Our results suggest that there is substantial room for
additional plant species across most areas of Europe, indicating that there is considerable scope for
implementing assisted colonization as a proactive conservation strategy under global warming without necessarily implicating negative effects on the native flora in the areas targeted for establishment of
translocated populations. Notably, our results suggest that 50% of the cells in Northern Europe, the
likely target area for many translocations, could harbor at least 1/3 as many additional species as they
have native species."
Michael Heim is a science teacher at Lac Courte Oreilles Ojibwe High School, Hawyard WI, whose students planted in May 2009 cloned cuttings from a very rare eastern native: the evergreen Box Huckleberry, Gaylussacia brachycera. The 2 page, photo-rich PDF of this article is a fascinating look at "rewilding" of an endangered species, based on a "deep-time" perspective in which "native" is regarded as including a plant's presumed preglacial regional distribution. In a March 5 comment posted on the Torreya Guardians site, Heim reports that he and his students have also planted cuttings from clones of Torreya taxifolia and Taxus floridana on the same tribal forest lands next to the school in northern Wisconsin, thus signifying another citizen-initiative of assisted migration, based on a deep-time understanding of native range.
"Scientists from the [Chicago Botanic Garden] are sending teams out across the Midwest and West to the Rocky Mountains and Great Basin to collect seeds from different populations of 1,500 prairie species by 2010, and from 3,000 species by 2020. The goal is to preserve the species and, depending on changes in climate, perhaps even help species that generally grow near one another to migrate to a new range." "'We recognize that climate change is likely to be very rapid and that seeds only disperse a few hundred yards, half a mile at most, naturally,' said Kayri Havens, the botanic garden's director of plant science and conservation. 'They'll need our help if we want to keep those species alive.'"
Abstract of paper available for online purchase: Rapid climate change has the potential to alter the location of bioclimatic envelopes for a significant portion of the world's flora. Plant species will respond variously via phenotypic plasticity, evolutionary adaptation, migration, or extinction. When fragmentation limits migration potential of many species or when natural migration rates are outstripped by the pace of climate change, some propose purposeful, human-mediated migration (assisted migration) as a solution. Here, we join the debate on assisted migration, and while recognizing the potential negative impacts, present a strategy to collect and bank seeds of plant species at risk of extinction in the face of rapid climate change to ensure that emerging habitats are as species-diverse as possible. We outline the framework currently being used by the Dixon National Tallgrass Prairie Seed Bank to prioritize species for seed banking, both for restoration purposes and for potential assisted migration in the future. We propose a strategy for collecting across the entirety of a species range, while targeting populations likely to go extinct under climate change, determined by application of species distribution models. Finally, we discuss current international efforts to collect and bank the global flora, as well as the research needs necessary to fully undertake the strategy presented.
Massive new report that goes beyond the usual IPCC report to make clear how the likely adverse effects of climate change are now thought to be much greater than even the IPCC reported. The section on "Management" contains a subsection on "Assisted Colonization" (p. 46 of the report; p. 4 of the PDF download), that includes these statements: "The reality of a rapidly changing climate has caught many natural-resource
managers and policy-makers unprepared. Large-scale translocations
might now be needed. Consequently, the conservation community needs
to move beyond the preservation or restoration of species and ecosystems
in place as the correct approach." and "Assisted colonization will always carry some risk, but these risks must be
weighed against those of extinction and ecosystem loss. Already some
regions of the Earth such as the Arctic are experiencing high levels of
warming. Many others will experience unprecedented heat within the next
100 years, as well as altered precipitation and ocean acidity. The future
for many species and ecosystems is so bleak that assisted colonization
might be their best chance. These management decisions will require
careful thought and will need to be backed up by detailed scientific
understanding if they are to succeed."
"We compared the natural ranges of 357 native European plant species with their commercial ranges, based on 246 plant nurseries throughout Europe. In 73% of native species, commercial northern range limits exceeded natural northern range limits, with a mean difference of ~ 1000 km. With migration rates of ~ 0.1 - 5 km per year required for geographic ranges to track climate change over the next century, we expect nurseries and gardens to provide a substantial head start on such migration for many native plants. While conservation biologists actively debate whether we should intentionally provide "assisted migration", it is clear that we have already done so for a large number of species." (excerpt from Abstract)
Cross-institutional report, with maps, on possible occurrence and velocity of climate change in California, along with response alternatives.
Survey of a shift in conservationists attitudes: "The point is not to think outside the box, but to recognize that the box itself has moved and, in the 21st century, will continue to move more and more rapidly," University of Colorado ecologist Timothy Seastedt and his colleagues write in the journal Frontiers in Ecology and the Environment. Seastedt and others argue land managers must focus on ecosystem diversity to give plants and animals the best chance to adapt to the change scientists say is coming: The more diversified a system, the more resilient. Trying to return ecosystems to some historic or natural state is no longer possible, they say. "To be honest, the combination of climate and atmospheric chemistries we're experiencing now — you can't find any historical match," Seastedt says.
Publisher's press release excerpt: Unfortunately, both assisted migration and Pleistocene rewilding would lead to managed ecosystems — the antithesis of wilderness. Just as we manage fisheries to preserve an important food source, we will have to give up some wildness in order to preserve species. "We can't protect all three faces of nature — ecosystem services, like clean water and fisheries; species diversity; and the feeling of wilderness — without somehow separating those three different concepts of nature and working with each one of them differently," [the author] says. "All can be complementary, but you have to do different things for each one. I think there are people who are quite happy to settle for one or two of those, but my personal philosophy and feeling is that we can have all three faces of nature." [The author] foresees two types of preserves, for example: species preserves to protect a species or assemblages of species, but requiring heavy management; and wildland preserves that retain ecological interactions without the influence of humans — the feel of wilderness — but which will see changing species and even extinctions.
Reports on the work of Greg O'Neill, a geneticist with the British Columbia Ministry of Forests and Range, who is already working with logging companies to replant logged forests in British Columbia not with the species that were logged, but with seeds of species currently native to much lower elevations or latitudes. [Same story also online at: http://www.cbsnews.com/stories/2009/07/20/tech/main5174392.shtml.]
Their most significant findings: 1. Butterfly diversity (the number of different species present) is falling fast at all the sites near sea level. It is declining more slowly or holding roughly constant in the mountains, except at tree line. 2. At tree line, butterfly diversity is actually going up, as lower-elevation species react to the warming climate by moving upslope to higher, cooler elevations. 3. Diversity among high-elevation butterflies is beginning to fall as temperatures become uncomfortably warm for them and, Shapiro says, "There is nowhere to go except heaven."
"As temperatures rise over the next century, three California amphibian species could be pushed to the cusp of extinction because the warming climate will effectively block their migration to more suitable habitats. Interventions by humans who physically relocate the animals may be the only way to help them survive. . . The Torreya Guardians, a self-organized group of naturalists, botanists, ecologists and others, are the most well-known proponents of assisted migration. Last July, the group planted endangered Torreya taxifolia seedlings in new habitat patches north of their customary domain in Florida, where it is becoming too hot for the conifers to survive." (and more)
Excellent summary of Camille Parmesan's early and continuing leadership in pointing out the shift poleward and upslope in native range of butterfly and other species, including her landmark 1996 and 2003 papers in the journal Nature. Parmesan is the lead scientist on the United Nation's Intergovernmental Panel on Climate Change (IPCC).
Lengthy news article that surveys the assisted migration debate, from its roots in a 2004 article in Wild Earth journal to citizen-activism, scientific backlash, and the beginnings of a worldview shift. The work of Torreya Guardians is highlighted, along with the August 2008 official filing, under the Endangered Species Act, of a request (by scientist Camille Parmesan) to undertake the first intentional movement of an animal species (an endangered butterfly) in response to shifting climate.
One of the top journals in science reports on the article (immediately below) that had been published in the other top science journal, plus coverage of the special session on assisted migration at the Ecological Society of America meeting in August 2008. Torreya Guardians is presented as taking the action lead in pressing for a rethinking of how biodiversity is best protected.
This 2-page article in America's top science journal has spurred enormous coverage and debate over the topic of what was once known as "assisted migration". Click here for news reports of the article:
Content: Right now this is just a skeleton website, as the group goes about its work. But after it achieves a product, estimated for autumn 2009, this will be a key site to watch. Right now, you can find a list of group leaders and members on that site. Check out their LIST OF PUBLICATIONS AND MEDIA REPORTS on this topic.
Hoegh-Guldberg says, "If we are to take the latest climate science seriously, then our current conservation strategies will not work for the majority of the species. To be blunt, they need to change. Even under the mildest rates of climate change, the habitat of many species will contract. Consequently, the future for many species and ecosystems is so bleak that assisted colonisation might be their only chance of survival."
A lengthy article featuring Camille Parmesan, first advocate for assisted migration among professional conservation biologists. Lots of excellent details on butterflies and other species threatened by climate change. Mentions work of Torreya Guardians in assisting Torreya taxifolia tree seedlings to venture northward in July 2008.
"We will review, identify, and work to revise all elements of the Service's legal, policy, and regulatory framework necessary to support effective adaptive responses to changing climate. We will place particular focus on developing necessary new policies (e.g., assisted colonization) and needed revision of existing policies (e.g., what constitutes native, invasive, or exotic species?)." p. 15 "Novel conservation and recovery actions, such as assisted colonization, will be developed and implemented to protect acutely climate-vulnerable species." (p. 16)
Strong argument against assisted migration in top ecological journal. Excerpt: "Until we develop more accurate and general
methods of predicting the impact of introduced species,
cost-benefit analyses will be dangerously misleading. It is not yet possible to quantify the probability
that a given species will go extinct because of climate
change, or that a translocated species will harm one or
more native species in a recipient community. To compare
two such illusory numbers would lead to a false sense of
scientific certainty. . . . Given this lack of predictive power, assisted colonization is tantamount to ecological roulette and should probably be
rejected as a sound conservation strategy by the precautionary
principle."
EXCERPT: The most recognized assisted migration project to date may be the Torreya Guardians. This network of conservationists, which includes botanists and ecologists, is trying to save the Torreya taxifolia, an endangered evergreen that grows to 60 feet in height. The group has transplanted dozens of trees from the Florida panhandle, where it is rapidly disappearing, to sites in North Carolina that are thought to have a suitable climate. "Plants are so much easier to replicate than pandas," said Rob Nicholson of the Botanic Garden at Smith College in Northampton, MA. "Torreya roots easily ... and you could start knocking them out by the tens of thousands if you wanted to."
Zimmer's survey includes the context of the Ricciardi and Simberloff paper (directly above), and Jessica Hellman's comment on that paper, where she says, "Is the alternative just to forsake a species?" she asks. "I just don't want to sit back and say, 'Oh the world is going to hell'."
Surveys managed relocations controversy as it pertains to insects; mention of need to assess insect tolerance of climate change in all their life stages; quotes Jessica Hellman.
Project proposed to re-introduce extinct populations of Bay Checkerspot at the famous site where Paul Ehrlich and students studied them for 5 decades: "'We may end up having to try to readjust natural communities all over the planet,' Ehrlich warned. 'Reintroduction is a dice game,' said Carol Boggs, a Stanford biologist who would direct the experiment. 'What we'd like to understand is how to load the dice in our favor. And this is the perfect place to try it.' Researchers will spend the next year designing the experiment, which must be approved by both Stanford officials and the U.S. Fish and Wildlife Service. Stanford spokesman Larry Horton cautions that the university has not yet taken a position. The U.S. Fish and Wildlife Service, which protects endangered species, said it would support the effort, if done correctly. The Stanford scientists would use contrasting strategies — perhaps introducing insects at different phases in the life cycle, into different plots, at different seasons, Boggs said. Mowing, grazing or other human interventions would be needed to sustain it. By managing the introduction, Stanford scientists would build, in essence, a butterfly lab."
Project abstract discusses methods to help ailing New Zealand bird, including assessment of assisted migration.
A terrific AUDIO exploration of the controversy, which aired 24 July 2008. Part 1 is the supportive side, via an interview with Prof. Camille Parmesan. Part 2 is an interview with an invasive species researcher that is very critical of the idea. Part 3 is a not-to-be-missed radio spoof of the idea.
A richly illustrated PHOTO-ESSAY, with links to a complete chronology, of the REWILDING ACTION that Torreya Guardians undertook for 31 potted seedlings. A writer and a photographer commissioned by Audubon magazine documented the action (which will probably be published in a summer 2009 issue of Audubon.
Excerpt: "Assisted translocation/migration represent new challenges in the face of climate change; species, particularly orchids, will need artificial assistance to migrate from hostile environments, across ecological barriers (alienated lands such as farmlands and built infrastructure) to new climatically buffered sites. It is likely that orchids, more than any other plant family, will be in the front-line of species to suffer large-scale extinction events as a result of climate change."
See also an online biogeographic article that reports on the existing use of assisted migration for Australian orchids.
Lots of excellent details on the AUSTRALIAN species for whom assisted migration is being assessed, plus scientists quoted pro and con.
ABSTRACT: Climate change is causing many organisms to migrate to track climatically-suitable habitat. In many cases, this will happen naturally, but in others, human intervention may be necessary in the form of "assisted colonisation." Species re-establishments in suitable parts of their historic ranges provide an opportunity to conserve some species and to test ideas about assisted colonisation. Here, bioclimatic models of the distributions of two extinct British butterflies, Aporia crataegi and Polyommatus semiargus, were used to investigate the potential for re-establishment in Britain. . .
Detailed news report of "the first successful test case of assisted colonization". In 1999 and 2000, scientists introduced populations of two species of butterfly miles north of their then-current range in England. A just-published paper reports the results:
Source: Willis, S.G. et al. 2009. Assisted colonization in a changing climate: a test-study using two U.K. butterflies. Conservation Letters DOI: 10.1111/j.1755-263X.2008.00043.x. Their abstracts concludes, "We suggest that assisted colonization
may be a feasible and cost-effective means of enabling certain species to track
climatic change."
The full title of Keel's thesis is "Assisted Migration as a Conservation Strategy for Rapid Climate Change: Investigating Extended Photoperiod and Mycobiont Distributions for Habenaria repens Nuttall (Orchidaceae) as a Case Study". The link above connects to a PDF of his chapter 3.
This short chapter will be useful for those engaged in considering whether "assisted migration" or "assisted colonization" is the best term for the kinds of conservation actions now beginning to be considered.
Torreya Guardians (and others) are invited to post comments on whether the original term, "assisted migration," should be replaced with the term more recently proposed, "assisted colonization."
Revisits a previous blog on the possible extinction of California's Joshua Tree, owing to an inability to disperse and thus track climate changes. In this blog, Clarke mentions the work of Torreya Guardians in assisting migration of a critically endangered tree in eastern North America.
Interview of scientists and managers working in Joshua Tree National Park; prospects for the extirpation of Joshua Trees in the park as climate changes; the role of extinct ground sloths in past seed dispersal of this tallest of all yuccas. Audio interview of a trip to a cave looking for sloth dung.
Subtitle: "Climate change will shuffle the deck of plants, animals, and ecosystems in ways we've only begun to imagine."
Content: Surveys beginnings of debate about whether to actively assist species in shifting their geographic ranges. The work of Torreya Guardians is mentioned.
Content: The paper begins, "The Torreya Guardians are trying to save the Florida torreya from extinction. . . The focus of Torreya Guardians is an 'assisted migration' program that would introduce seedlings to forests across the Southern Appalachians and Cumberland Plateau. Their intent is to avert extinction by deliberately expanding the range of this endangered plant over 500 km northward. . . If circumventing climate-driven extinction is a conservation priority, then assisted migration must be considered a management option. . . Assisted migration is a contentious issue that places different conservation objectives at odds with one another. This element of debate, together with the growing risk of biodiversity loss under climate change, means that now is the time for the conservation community to consider assisted migration. Our intent here is to highlight the problem caused by a lack of a scientifically based policy on assisted migration, suggest a spectrum of policy options, and outline a framework for moving toward a consensus on this emerging conservation dilemma."
Content: Superb and lengthy science reporting on the above paper that appeared in Conservation Biology, with much additional information, insights, and arguments culled from the authors and other scientists and conservation managers. Highlights issues related to speed of migration (past evidence as well as estimates of future needs) and regional changes in climate. An article referenced within the report by Jason McLachlan et al., is also important to read: "Molecular Indicators of Tree Migration Capacity Under Rapid Climate Change" in Ecology, 2005, Vol 86, pp. 2088-98.
Content: References a forthcoming paper to be published in the journal Conservation Biology that encourages debate on the topic, by Mark Schwartz, Jason McLachlan, and Jessica Hellman
Content: Distinguishes history of inter- v. intra-continental invasive species in assessing the risks. Concludes that fish and crustaceans may pose a high risk. "We conclude that the risk of AM to create novel invasive species is small, but assisted species that do become invasive could have large effects."
Content: Great intro for popular audiences; shows lab experiments with insects in climate simulated settings.
Endangered Species Act invoked by Center for Biological Diversity to protect pikas threatened by global warming in the alpine peaks home in mainland U.S. No mention yet of assisted migration for the subspecies of pika trapped on warming mountain tops.
News report on the 18 July 2008 paper in Science by Hoegh-Guldberg et. al (above).
Great overview of looming problems for ecosystems (such as the Everglades) and species (such as Mountain Pica), some of which are already happening. No mention of assisted migration, of course, as this degree of human intervention would be a very delicate issue for the "wildest" of landscapes, especially for formally designated wilderness areas.
A 4.3 degree F. area-specific rise in temperature over the past century has affected plants in this sacred spot of environmentalism in Massachusetts. Notably, the plants hardest hit are those that did not alter their spring flowering time in tandem with the shift in earlier seasonal warming.
The IUCN has issued a report on "climate change susceptible" species. "Assisted migration" is mentioned as one of the possible management responses, as well as enlarged biological preserves and focussing on entire ecosystems, not merely individual species.
ABRSTRACT: Starting in the late 1970s, ecologists began unraveling the role of recently extinct large vertebrates in evolutionary ecology and ecosystem dynamics. Three decades later, practitioners are now considering the role of ecological history in
conservation practice, and some have called for restoring missing ecological functions and evolutionary potential using
taxon substitutes extant, functionally similar taxa to replace extinct species. This pro-active approach to biodiversity
conservation has proved controversial. Yet, rewilding with taxon substitutes, or ecological analogues, is now being
integrated into conservation and restoration programmes around the world. Empirical evidence is emerging that
illustrates how taxon substitutions can restore missing ecological functions and evolutionary potential. However, a major
roadblock to a broader evaluation and application of taxon substitution is the lack of practical guidelines within which
they should be conducted. While the International Union for Conservation of NatureĠs reintroduction guidelines are an
obvious choice, they are unsuitable in their current form. We recommend necessary amendments to these guidelines to
explicitly address taxon substitutions. A second impediment to empirical evaluations of rewilding with taxon substitutions
is the sheer scale of some proposed projects; the majority involves large mammals over large areas. We present and discuss
evidence that large and giant tortoises (family Testudinidae) are a useful model to rapidly provide empirical assessments
of the use of taxon substitutes on a comparatively smaller scale. Worldwide, at least 36 species of large and giant tortoises
went extinct since the late Pleistocene, leaving 32 extant species. We examine the latent conservation potential, benefits,
and risks of using tortoise taxon substitutes as a strategy for restoring dysfunctional ecosystems. We highlight how,
especially on islands, conservation practitioners are starting to employ extant large tortoises in ecosystems to replace
extinct tortoises that once played keystone roles.
Content: 37 Bolson Tortoises (larger than a desert tortoise) were moved from a private ranch in Arizona to protected lands in New Mexico where they are being bred and managed expressly for "rewilding" into their former habitat.
Abstract: Ecological restoration in North America traditionally has strived to return ecosystems to some semblance of the early historic (post-Columbian) condition. Emerging alternative paradigms recognize the large impacts exerted by pre-Columbian peoples, the ever-changing nature of ecosystems regardless of anthropogenic effects, and the possibility of using other benchmarks. Recently, the Turner Endangered Species Fund initiated a project to restore the endangered bolson tortoise to an area in southern New Mexico within its late Pleistocene, but not historic range. Justifications included the likelihood that prehistoric humans extirpated it from New Mexico, the presence of habitats similar to those in its current range in Mexico, and escalating threats to species there. . . Restoring imperiled species to prehistoric ranges has some precedent in North America and, we believe, merits increasing consideration as historic ranges of some species offer increasingly less security.
Content: Aldabran Giant Tortoises used as proxies for the Mauritius giant tortoises that had been exterminated. "Rewilding" a small island near Mauritius with these giant tortoises.
Barlow and Martin 2004 proposed that Torreya taxifolia might have gotten trapped in its peak-glacial pocket reserve (in northern Florida) for lack of its coevolved seed disperser, and thus was unable to geographically respond to the warming interglacial climate. The above paper suggests that another taxon of gymnosperm that thrived (along with genus Torreya) in the Jurassic period might have suffered from an inability to easily track climate change when the seed-dispersing dinosaurs died out.
Download in PDF two articles, for and against assisted
migration of Torreya taxifolia, published as the featured
Forum in the Winter 2005 issue of Wild Earth. Download
the pro and con articles separately for printing on standard
size paper. Or, for viewing the 2-article Forum as it
appeared in publication (wide-screen, with all illustrations),
download the "Forum."
FOR assisted migration, by Connie Barlow & Paul Martin
ANTI assisted migration by Mark Schwartz
FORUM (both articles for wide screen)
Content: News report on how climate change will threaten animal and plant species; includes coverage of Torreya taxifolia and mentions Torreya Guardians.
Content: Blogs and comments debate "assisted migration/colonization" with respect to snails; includes some case history of attempt to relocated endangered snails from New Zealand mainland to an island off NZ.
Content: Editorial in favor of assisted migration for endangered species.
Content: Advocacy and statement of conditions that merit assisted migration intervention for orchids
Content: Makes case for using the term "assisted colonization" rather than "assisted migration"; proposes three features for testing advisability of any particular species for such intervention: (1) their probability of extinction due to climate change, (2) their vagility, (3) and their ecological roles.
Content: Governmental publication in favor of assisted migration of tree species in anticipation of climate change.
Content: Effect of global warming on California blue oaks and other trees.
Content: Marine biologist highly skeptical of the merits of considering assisted colonisation for marine species.
Content: Professor Lesley Hughes, co-author of the 18 July 2008 paper in the journal Science (O. Hoegh-Guldberg et. al), is interviewed by the web news of her university. Also click on an AUDIO INTERVIEW with Professor Hughes (scroll down to 30 June 2008, "Climate Change Peril").
Content: The first advocacy article ("commentary") by prominent conservation biologists that proposes "rewilding" close-kin of some of the large mammals that went extinct in North America at the end of the Pleistocene, 13 thousand years ago by reintroducing close relatives or proxies.
Content: This is the long and fully developed version of the 2005 paper, by the same set of authors. Abstract: Large vertebrates are strong interactors in food webs,
yet they were lost from most ecosystems after the dispersal of modern
humans from Africa and Eurasia. We call for restoration of missing
ecological functions and evolutionary potential of lost North American megafauna using extant conspecifics and related taxa. We refer
to this restoration as Pleistocene rewilding; it is conceived as carefully
managed ecosystem manipulations whereby costs and benefits are
objectively addressed on a case-by-case and locality-by-locality basis.
Pleistocene rewilding would deliberately promote large, long-lived
species over pest and weed assemblages, facilitate the persistence and
ecological effectiveness of megafauna on a global scale, and broaden
the underlying premise of conservation from managing extinction
to encompass restoring ecological and evolutionary processes. Pleis
tocene rewilding can begin immediately with species such as Bolson
tortoises and feral horses and continue through the coming decades
with elephants and Holarctic lions. Our exemplar taxa would con-
tribute biological, economic, and cultural benefits to North America.
Owners of large tracts of private land in the central and western
United States could be the first to implement this restoration. Risks
of Pleistocene rewilding include the possibility of altered disease ecol-
ogy and associated human health implications, as well as unexpected
ecological and sociopolitical consequences of reintroductions. Estab-
lishment of programs to monitor suites of species interactions and
their consequences for biodiversity and ecosystem health will be a
significant challenge. Secure fencing would be a major economic cost,
and social challenges will include acceptance of predation as an over-
riding natural process and the incorporation of pre-Columbian eco-
logical frameworks into conservation strategies.
Content: Lengthy interview with Connie Barlow discussing the Pleistocene megafaunal rewilding concept. Very useful links to other related articles and audios at the end.
ABSTRACT of paper: Although the North American megafaunal extinctions and the formation of novel plant communities are well-known features of the last deglaciation, the causal relationships between these phenomena are unclear. Using the dung fungus Sporormiella and other paleoecological proxies from Appleman Lake, Indiana, and several New York sites, we established that the megafaunal decline closely preceded enhanced fire regimes and the development of plant communities that have no modern analogs. The loss of keystone megaherbivores may thus have altered ecosystem structure and function by the release of palatable hardwoods from herbivory pressure and by fuel accumulation. Megafaunal populations collapsed from 14,800 to 13,700 years ago, well before the final extinctions and during the Bżlling-Allerżd warm period. Human impacts remain plausible, but the decline predates Younger Dryas cooling and the extraterrestrial impact event proposed to have occurred 12,900 years ago.
Content: Lengthy report on the author's visits to talk with some of the leaders in Pleistocene Rewilding movement.
Content: A long report of the rewilding of Europe's endangered native bison to a 500 acre preserve in Latvia that will also contain other surrogates for Pleistocene megafauna.
Tag line: Unsatisfied with merely halting environmental destruction, some conservationists are trying to reconstruct ecosystems of the past. Emma Marris travels back in time with the rewilders.
Content: We argue that the introduction of non-native extant tortoises
as ecological replacements for extinct giant tortoises
is a realistic restoration management scheme, which is
easy to implement. We discuss how the recent extinctions
of endemic giant Cylindraspis tortoises on the Mascarene
Islands have left a legacy of ecosystem dysfunction threatening
the remnants of native biota, focusing on the island
of Mauritius because this is where most has been inferred
about plant-tortoise interactions. There is a pressing need
to restore and preserve several Mauritian habitats and
plant communities that suffer from ecosystem dysfunction.
13 pages, with color illustrations, on island restoration and rewilding efforts focusing on using congenerics or other species proxies where extinctions preclude restoring historically native species with whom extant native plants coevolved.
Content: Meshes "ecological anachronisms," conservation biology, rewilding of ecological proxies/analogs, and assisted migration/colonization, in a landmark paper that experimentally demonstrates the ecological viability and conservation value of introducing Aldabran tortoises to the oceanic island of Mauritius as ecological proxies (seed-dispersal agents) for Mauritian tortoises that were driven into extinction by humans.
Content: News report on the American Naturalist paper cited above.
Content: Editorial generally supportive of the August 2005 paper in Nature.
Content: Lots of quotes from Dr. Mark Schwartz on the assisted migration issue.
Lead author of the "Pleistocene Rewilding" paper originally published in Nature writes for a popular audience and responds to criticism that has emerged.
Proposes rewilding the endangered Asiatic lion into Europe.
Ongoing reports, news articles, and blog entries on this topic, posted at the The Rewilding Institute website.
Wikipedia entry, with photos and references, on this topic.
For those of us considering the importance of "assisted migration" of species impacted by climate change, or outright "rewilding" of species or surrogates to regions in which they lived thousands of years ago, this paper is something to ponder. Here the author proposes that the collapses of fisheries in the North Atlantic may be irreversible without infusion of new species diversity, and that much is to be gained (and little risked) by introducing North Pacific fishes into the North Atlantic. The deep-time discussion of "The Great Trans-Arctic [Marine] Biotic Interchange" (which began 3.5 million years ago when the Bering Land Bridge was transgressed by marine waters), is crucial reading for those of us working with entirely terrestrial biotas.
Interview published on the Action Bioscience website, an education resource of the American Institute of Biological Science
Useful blogpost and comments on the possibility of cloning frozen mammoth DNA from flesh or sperm.