Wildlife reintroduction is a conservation strategy employed to return threatened or endangered species to their natural habitats. It may involve using captive breeding programs or the translocation of individuals from one population to another. Wildlife reintroduction can be a lengthy, complex, and expensive operation that requires a multidisciplinary approach.
There are several types of wildlife reintroductions that take place depending on the circumstances of the species in question. Reintroduction (sometimes called re-establishment) refers to an attempt to establish a species in an area which was once part of its historical range where it has now become either extirpated or extinct [1] Translocation refers to the deliberate movement of wild individuals or populations from one part of their natural range to another.[1] Reinforcement or supplementation refers to the process of adding individuals to an already existing population.[1] Finally, conservation or benign introduction refers to attempts to establish a species in an area outside of its historic range, but within an appropriate habitat when its natural habitat has been lost or destroyed.[1]
IUCN Involvement
editThe International Union for Conservation of Nature is involved in many aspects of conservation including wildlife reintroduction. The Reintroduction Specialist Group, who operates under the IUCN Species Survival Commission, has put forth a set of guidelines to aid in wildlife reintroduction operations.
IUCN Guidelines
editThe IUCN guidelines suggest a multi-step, multidisciplinary approach to conducting wildlife reintroductions. These guidelines are summarized below and can be downloaded from the IUCN website. According to the IUCN, the objectives of a re-introduction may include enhancing the long-term survival of a species, re-establishing a keystone species (in the ecological or cultural sense) in an ecosystem, maintaining and/or restoring natural biodiversity,providing long-term economic benefits to the local and/or national economy, promoting conservation awareness, or a combination of these.[1]
Pre-Project Activities
editBiological
editFeasibility Study and Background Research
editAn assessment should be made of the taxonomic status of individuals to be reintroduced. Detailed studies should be made of the status and biology of wild populations (if they exist) to determine the species' critical needs. The species, if any, that has filled the void created by the loss of the species concerned, should be determined; an understanding of the effect the re-introduced species will have on the ecosystem is important for ascertaining the success of the re-introduced population.[1]
Previous Reintroductions
editThorough research into previous re-introductions of the same or similar species and wide-ranging contacts with persons having relevant expertise should be conducted prior to and while developing re-introduction protocol.[1]
Choice of Release Site & Type
editSite should be within the historic range of the species.For wildlife reintroductions there should be no remnant population to prevent disease spread, social disruption and introduction of alien genes. In some circumstances, a reintroduction or reinforcement may have to be made into an area which is fenced or otherwise limited, but it should be within the species' former natural habitat and range.[1]
Evaluation of Reintroduction site
editAvailability of suitable habitat: re-introductions should only take place where the habitat and landscape requirements of the species are satisfied, and likely to be sustained for the forseeable future. Identification and elimination, or reduction to a sufficient level, of previous causes of decline is vital to success. This could include disease; over-hunting; over-collection; pollution; poisoning; competition with or predation by introduced species; habitat loss; adverse effects of earlier research or management programs; competition with domestic livestock, which may be seasonal.[1]
Availability of Suitable Release Stock
editIdeally, source animals will come from wild populations. If there is a choice of wild populations to supply founder stock for translocation, the source population should be closely related genetically to the original native stock and show similar ecological characteristics (morphology, physiology, behavior, habitat preference) to the original sub-population. Removal of individuals for reintroduction must not endanger the captive stock population or the wild source population. Stock must be guaranteed available on a regular and predictable basis, meeting specifications of the project protocol.[1]
Release of Captive Stock
editMost species of mammal and birds rely heavily on individual experience and learning as juveniles for their survival; they should be given the opportunity to acquire the necessary information to enable survival in the wild, through training in their captive environment; a captive bred individual's probability of survival should approximate that of a wild counterpart. Care should be taken to ensure that potentially dangerous captive bred animals (such as large carnivores or primates) are not so confident in the presence of humans that they might be a danger to local inhabitants and/or their livestock.[1]
Socio-Economic & Legal Requirements
editA thorough assessment of attitudes of local people to the proposed project is necessary to ensure long term protection of the re-introduced population, especially if the cause of species' decline was due to human factors (e.g. over-hunting, over-collection, loss or alteration of habitat). The program should be fully understood, accepted and supported by local communities.[1] Re-introduction must take place with the full permission and involvement of all relevant government agencies of the recipient or host country. This is particularly important in reintroductions in border areas, or involving more than one state or when a re-introduced population can expand into other states, provinces or territories.[1]
Planning, Preparation & Release Stages
editShould include construction of a multidisciplinary team with access to expert technical advice for all phases of the program and identification of short- and long-term success indicators and prediction of program duration, in context of agreed aims and objectives.[1]
Post-Release Activities
editPost release monitoring is required of all (or sample of) individuals. This most vital aspect may be by direct (e.g. tagging, telemetry) or indirect (e.g. spoor, informants) methods as suitable.
Captive Breeding
editMany studies have been conducted attempting to assess the survivorship of captive-bred reintroduced individuals compared with wild-caught and translocated individuals. A study conducted in Sweden examined the survivorship of captive-bred and wild-caught European Otters and found the survival rate after one year was 79% in wild-caught otters and 42% in captive-bred otters. [2] A review of scientific studies focusing on the success and survivorship of captive-born versus wild-caught carnivores found that wild-caught carnivores are significantly more likely to survive than captive-born carnivores in reintroductions and that reintroduced captive-born carnivores are particularly susceptible to starvation, unsuccessful predator/competitor avoidance, and disease.[3] Lower survivorship is one of many concerns when releasing captive-bred individuals into the wild. Other potential concerns include 1. problems with establishing self-sufficient captive populations 2. poor success in reintroductions 3. high costs 4. domestication 5. preemption of other recovery techniques 6. disease outbreaks and 7. maintaining administrative continuity.[4]
While captive breeding may have its drawbacks, there are many situations in which we have no other option. When a species’ population is drastically reduced, sometimes to the point of being declared extinct in the wild, it may become necessary to develop a captive breeding program and there are many that have seen success. The story of the Red Wolf (Canis rufus rufus) a species whose population was down to 14 breeding individuals in captivity is a prime example of a species that is slowly moving toward recovery with a current wild population of over 100 individuals. [5] [6]
Assessing Success
editA key aspect of any undertaking is establishing a measure of success. Success in wildlife reintroduction has been defined in many ways. Some suggest that breeding by the first generation or a three-year breeding population with recruitment exceeding adult death rate[7] are indicators of success. Other definitions suggest placing a numerical goal such as reaching an unsupported population of at least 500 individuals.[8] Still others have said success is achieved with the establishment of a self-sustaining population.[9]
It has been suggested that the problem with all of these definitions is that they rely on a set measure of time. Any given project can only be said to have achieved its aim at the time at which the assessment is made.[10] The environment is constantly changing and with these changes a species that may be defined as successful could later crash. The reintroduction of Arabian oryx in the Sultanate of Oman is an example of this very thing. Once considered to be one of the reintroduction success stories,[10] [11] almost two decades after the first releases of oryx, an epidemic of poaching over a three-year period rendered the free-ranging oryx population no longer viable.[12] [10] Our ever-changing environment requires us to accept a more fluid definition of success that relies on post-release monitoring and management with the aim to achieve population persistence without intervention.[10]
On-Going Programs
editUnited States
editRed Wolf Recovery Program[13]
Mexican Grey Wolf Recovery Program[14]
Whooping Cranes[15]
Clackamas Bull Trout[16]
Black-footed Ferret Recovery Program[17]
References
edit- ^ a b c d e f g h i j k l m n "IUCN Guidelines for Re-Introductions" (PDF).
- ^ Sjoasen, Thomas (1996). "Survivorship of Captive-Bred and Wild-Caught Reintroduced European Otters in Sweden". Biological Conservation. 76: 161–165.
- ^ Snyder, Noel (1996). "Limitations of Captive Breeding in Endangered Species Recovery". Conservation Biology. 10 (2): 338–348.
{{cite journal}}: Unknown parameter|coauthors=ignored (|author=suggested) (help); Unknown parameter|month=ignored (help) - ^ "Red Wolf Recovery Program". USFWS.
- ^ Jule, Kristen (2008). "The Effects of Captive Experience on Reintroduction Survival in Carnivores: A Review and Analysis". Biological Conservation. 141: 355–363.
{{cite journal}}: Unknown parameter|coauthors=ignored (|author=suggested) (help) - ^ Hedrick, P.W. (2008). "Captive Breeding and the Reintroduction of Mexican and Red Wolves". Molecular Ecology. 17: 344–350.
{{cite journal}}: Unknown parameter|coauthors=ignored (|author=suggested) (help) - ^ Sarrazin, Francois (1996). "Reintroduction: Challenges and Lessons for Basic Ecology". Trends in Ecology and Evolution. 11 (11): 474–478.
{{cite journal}}: Unknown parameter|coauthors=ignored (|author=suggested) (help); Unknown parameter|month=ignored (help) - ^ Beck, B.B. (1994). "Reintroduction of Captive-Born Animals". Creative Conservation: 265–286.
{{cite journal}}: Unknown parameter|coauthors=ignored (|author=suggested) (help) - ^ Griffith, B (1989). "Translocation as a Species Conservation Tool: Status and Strategy". Science. 245: 477–480.
{{cite journal}}: Unknown parameter|coauthors=ignored (|author=suggested) (help) - ^ a b c d Seddon, Philip (1999). "Persistence Without Intervention: Assessing Successs in Wildlife Reintroductions". Trends in Ecology and Evolution. 14 (12): 503.
- ^ May, R (1991). "The Role of Ecological Theory in Planning Reintroduction of Endangered Species". Symposium of the Zoological Society of London. 62: 145–163.
- ^ Gorman, M (1999). "Conservation: Oryx Go Back to the Brink". Nature. 398: 190.
- ^ "Red Wolf Recovery Program". USFWS.
- ^ "Mexican Grey Wolf Recovery Program". USFWS.
- ^ "Reintroduction of a Migratory Flock of Whooping Cranes in the Eastern United States". USFWS.
- ^ "Bull Trout Reintroduction Project". USFWS.
- ^ "Black-footed Ferret Recovery Program". Black-footed Ferret Recovery Implementation Team.