Assisted Migration or Assisted Colonization: What's In a Name?
Commentaries solicited by Torreya Guardians
Background
From its beginning in 2004, the very loose-knit organization Torreya Guardians was formed to move ahead with "assisted migration" for one highly endangered species, Torreya taxifolia. The organization has its roots in a paper published in the Fall 2004 issue of Wild Earth, titled "Bring Torreya taxifolia North — Now," by Connie Barlow and Paul S. Martin. This article was published about a year after email debate and communications had been ongoing among a dozen naturalists, botanists, and ecologists, among them Barlow, Martin, Hazel Delcourt, Bill Alexander, Peter White, Mark Schwartz. Barlow and Martin decided that the group could not reach common ground and thus split off to publicly propose the radical end: assisted migration. Importantly, their published article established the rationale for such assistance not only in the plant's neediness, but also from a deep-time perspective that portrayed the plant as simply being given some assistance for moving back to what would have been its "native habitat" in prior instances of interglacial warmings over the past several million years.
In "Climate Change and Moving Species: Furthering the Debate on Assisted Colonization", by Malcolm L. Hunter Jr. (Conservation Biology Vol 20(5), 2007), the term assisted colonization was proposed as a replacement for the original term assisted migration (the latter likely to have been first used by ecologist Brian J. Keel). Hunter wrote:
"I have used the term assisted colonization in contrast to assisted migration used by McLachlan et al. because many animal ecologists reserve the word migration for the seasonal, round-trip movements of animals (Wilcove 2007) and because the real goal of translocation goes beyond assisting dispersal to assuring successful colonization, a step that will often require extended husbandry."
18 July 2008, marked a Policy Forum posting that furthered the term "assisted colonization": POLICY FORUM: ECOLOGY: "Assisted Colonization and Rapid Climate Change" by O. Hoegh-Guldberg, L. Hughes, S. McIntyre, D. B. Lindenmayer, C. Parmesan, H. P. Possingham, and C. D. Thomas, in Science 18 July 2008: 345-346.
This webpage has been created to support moderated discussion of the choice in terminology: assisted colonization v. assisted migration. The first posting is by webmaster and Torreya Guardians founder Connie Barlow.
Here are the reasons that I advocate for retention of the original term, "assisted migration":
1. Unfortunately, for many of us, the term "colonization" has hegemonic overtones harking back to European "colonization" of the world. In contrast, "migration" has an immediate natural and organic cast to it.
2. "Migration" has its emphasis on the movement itself — thus feeling less interventionist than a word that places emphasis on a desired end result, "colonization." Indeed, "assisted migration" evokes subsequent discussion of how much to assist the species in its success, once the act of migration itself is completed. For example, Torreya Guardians are now discussing whether or not to assist its rewilded T. taxifolia seedlings with soil supplementation/liming at the time of forest plantings (scheduled for July 30, 2008 in Waynesville NC). In contrast, the term "colonization" implies that the effort is incomplete unless management interventions continue after the transfer, toward the goal of ensuring successful establishment and eventual reproduction. (Note: If one provides soil supplementation or other assistance as a norm upon arrival, then there is less opportunity to "read" the response of the species itself as to whether the landing site actually meets all its needs, or whether, in fact, a better migration target might be attempted with a subsequent batch of immigrants.)
3. "Migration" inclines one to think that either something has gone catastrophically wrong with the native home, or that the movement is part of recurring cyclic phenomena — seasonal in the case of Monarch butterflies, or in the case of genus Torreya (and presumably many other nonendangered plants), cyclic movement of plants upslope/downslope or north/south in sync with the pulses of glacial warming and cooling at the scale of geologic time. In contrast, "colonization" may indicate movement of an expansionist (opportunistic or hegemonic) cast, even while the home range is still quite viable for the species in question.
4. "Migration" is suggestive of more localized and contiguous movements, whereas "colonization" often refers to human-led actions that can spot-move from and to anywhere on the globe — indeed, even interplanetary, as in "colonization of Mars" or establishment of a human "colony" on the moon.
I was personally particularly keen that this issue be described as
"assisted colonisation" rather than the more commonly used "assisted
migration". This is my personal view, and other authors of our paper might
possibly wish to add something.
In common usage (outside pure science), "migration" is most commonly used
in two major contexts.
The first, and most common, is to describe the seasonal return migration of
birds and other groups of animals. This is quite clearly NOT what is being
discussed. There are already policy reports and published scientific papers
on the potential consequences of climate change for these "true" migrants,
so I believe that it will be very confusing to use "assisted migration" as
the general term to describe the type of endeavour we are discussing.
The second common useage relates to human migration, meaning the net flow
of people from one region to another. The connection with this is also
undesirable because (a) this already has a negative image in many people's
minds, and (b) it usually represents the flow of individuals from one
region to another, already populated, region, rather than establishment in
an area without human populations.
In a scientific context, the term migration is also sometimes used in
ecology to describe the unidirectional movement of individuals from one
location to another. However, migration in this context normally means the
act of movement itself, and not the establishment of new populations in the
locations where individuals arrive (although this may be the consequence).
Assisted colonisation does not stop at moving individuals; it may also
require preparation (and protection) of sites to receive the immigrants,
and subsequent management of the establishing population until such time as
a self-sustaining population has been achieved.
My personal belief is that "assisted colonisation" avoids confusion with
other types of migration, and identifies that establishing populations at
the destination is the key goal (not simply moving individuals).
best wishes,
Dear Connie et al:
I understand that I am the person responsible for the proposed switch to "assisted
colonization", and having read the four reasons you support continued use of "assisted
migration" I have to stand by my original argument and agree with Chris' elaboration.
"Colonization" is a perfectly acceptable word among ecologists, and your concerns about its
"hegemonic overtones" will not worry most scientists who are primarily concerned with
evaluating this management option in clear language rather than advocating it with the
public.
mac hunter
I agree completely, and in one of my interviews I clarified this point
also, although not as clearly as you have, Chris.
Dear Connie, My own concern about "assisted colonization" is the same that Chris Thomas raises in his email about "assisted migration." So, clearly, this needs more discussion. I tend to think of "colonization" in the way that it is defined by the invasion pathway — as the first step in population establishment. Instead, we might envision more conservation action than just establishment. But then, Thomas says the same about "assisted migration" and doesn't feel that "assisted colonization" has that problem. Again, I'll do my best to raise your concerns at the meeting.
Just previous to the ESA meeting, we're gathering a group of conservation biologists, invasion biologists, lawyers, ethicists, and economists to form a working group that we think will have something meaningful to contribute to this issue. (The working group is being convened by myself, Mark Schwartz, Jason McLachlan, and Dov Sax.) We'll talk about the naming issue with that group as well, and I'll let you know what they had to think.
I've seen your site, and I've enjoyed watching it grow. Thanks very much for your efforts on this important issue — you guys started it all!
After reading all 4 comments (above), I now feel less squeamish about the terminology for this effort shifting from the original "assisted migration" to "assisted colonization". From my deep-time perspective (see my 2001 book, The Ghosts of Evolution), and having been inspired to begin the discussion that eventuated in Torreya Guardians after I read Forests in Peril: Tracking Deciduous Trees from Ice-Age Refuges into the Greenhouse World (2002, by palynologist and deep-time ecologist Hazel Delcourt), I still regard "migration" as the preferred term. This is because I regard our assistance today as mimicking actual migration patterns that likely played out as climate warmed during previous peak-interglacial periods — that is, episodes of climate change in which human interference in the natural world had not yet disrupted the continuity of natural corridors for long-term migratory movement, and when humanity had not yet undermined natural dispersal by extincting or extirpating seed dispersers of plants (such as tortoises and squirrels as dispersers of Torreya taxifolia).
One other term I'd like to toss into the mix for discussion: rewilding. Rewilding was introduced professionally in the following two papers: (1) "Rewilding North America" by Josh Donlan and 11 other authors, Nature, 18 August 2005 (2 pages), and (2) "Pleistocene Rewilding: An Optimistic Agenda for the 21st Century" by Josh Donlan and 11 other authors, American Naturalist, November 2006, vol 168: pp 660-681. Yesterday, a group of Torreya Guardians, colleagues, and a writer and photographer recording the event for Audubon magazine undertook what we regard as the first rewilding of the highly endangered "Florida" conifer, Torreya taxifolia. Others have already intentionally or unintentionally planted this species northward into the Appalachian Mountains in ways that constitute "assisted migration" or perhaps even "assisted colonization", but such plantings in home gardens and institutional botanical gardens are not in wild, forested habitats — nor in great enough numbers to ensure long-term population survival and pollination in this dioecious species (male and female reproductive organs occurring on separate plants).
Yesterday, we planted 10 seedlings on one property and 21 on a second property in the vicinity of Waynesville, NC. Elevations were 2600 and 3400 feet, respectively. We chose natural forested landscapes with fully deciduous canopy, on somewhat steep slopes. Deciduous canopy will allow this subcanopy evergreen conifer to have access to nearly full sun in the early spring and late fall (as well as winter). Significantly, at both sites where our potted seedlings of Torreya taxifolia were planted, dying hemlocks were evident. Perhaps this "deep-time native" of the Appalachians will be able to ecologically serve its forest community in ways similar to that of the beleaguered eastern hemlock.
Of interest, I have been receiving "Google alerts" for the terms "assisted migration", "assisted coloniz/sation" and the results are fascinating. About a quarter refer to precisely the issue we are dealing with, but check out some of these other usages of the term:
12/14/08: "Slow-moving cranesWeather has not cooperated with this yearŐs ultralight-assisted migration of whooping cranes."
12/08/08: "Displaced Darfuris response to joint Arab-African peace initiative for Darfur:
SLM Nur's rebels in Darfur's Kalma Camp dismiss peace talks and demand more UN security or assisted migration out of Sudan."
12/05/08: "Called the Assisted Migration Adaptation Trial, the long-term research project aims to better understand the climatic tolerance of all of B.C.Ős tree species, then take that information to better refine the provinceŐs reforestation strategies as it relates to climate change."
NOTE: Chris Thomas (Dept. Biology, University of York, UK) sent this statement by email reply to Torreya Guardians in response to Connie Barlow's request for elaboration. It is printed with permission of the author.
Chris Thomas
NOTE: Malcolm Hunter (Dept. Wildlife Ecology, University of Maine, USA) sent this statement by email reply to Torreya Guardians in response to Connie Barlow's request for elaboration and Chris Thomas's reply to her. It is printed with permission of the author.
NOTE: Hugh Possingham (Centre for Applied Environmental Decision Analysis, University of Queensland, Australia) sent this statement by email reply to Chris Thomas, and cc-d Torreya Guardians. It is printed with permission of the author.
NOTE: Jessica Hellmann (Dept. Biological Sciences, University of Notre Dame, USA) sent this statement by email reply to Torreya Guardians in response to Connie Barlow's request for elaboration. It is printed with permission of the author.
Thank you for your email. I am sympathetic to your concerns, and we will discuss it at the ESA meeting. I also understand the authors' worry that "migration" tends to refer to seasonal movements, e.g., migratory birds. But I also think that the term "migration" is also well defined in the paleo literature with the definition that we intend in this modern context.
Best wishes,
Jessica
I have noticed the term assisted colonization showing up in several sources. I feel that assisted colonization and assisted migration are two similar but separate concepts. The attached document is part of chapter one of my dissertation that may help clarify the difference. [Editor's Note: Click for "Defining Migration" chapter or "Assisted Migration" chapter.
I just learned about the url posted by the group of conservation biologists, lawyers, and ethicists that met just prior to the Ecological Society of America meeting in August 2008, and whose goal is to produce a document to guide others in these fields and governmental and private conservation managers on how to deal with this issue. Notably, the website is called "Managed relocation". However, right under the home page title appears this list:
Working group on managed relocation
Here is a clip from the Info about MR page within that site:
Working group on assisted migration
Working group on assisted colonization"Managed relocation" (also called "assisted migration" or "assisted colonization") is the purposeful translocation of species adversely affected by global change, particularly climate change. Goals of managed relocation include, but are not limited to, the reduction of extinction risk, the enhancement of evolutionary potential, and the enhancement of ecosystem services.
Connie Barlow speaking here, with Torreya Guardians, I find I prefer "managed translocation" to "managed relocation" for the same reason that I preferred "assisted migration" to "assisted colonization", as the former implies (to me) more of a boost to a species, giving it a chance, rather than a highly interventionist goal to have that boost succeed. For example, Torreya Guardians planted seedlings of Torreya taxifolia into a natural forest situation on private lands in the mountains of North Carolina in July 2008. If those seedlings do not survive and grow pretty much on their own here, then that will be an indication that (a) the troubles the species has in northern Florida is not just climate-induced, or (b) maybe we ought to try a north-facing slope, a higher elevation, or a more northerly latitude.
The terms "assisted migration" and "assisted colonization" are terms that have been used to refer to the same basic strategy as "managed translocation." In Aug., 2008, this working group suggested a more comprehensive term, "managed relocation." We prefer "managed relocation" because it captures the concept of persistent intervention (if necessary) and emphasizes the geographical movement of organisms, a conservation or management concept particularly distinctive to the modern era of climate change. In several locations on this website, however, you will see use of "assisted migration" because it captures the essence of managed relocation in the sense of geographic movements that actors pursue in a helpful or beneficial sense.
1/12/08: "Rush University Medical Center will also be using the Acuo DICOM Assisted Migration (ADAM) to move data from the existing proprietary archive