Editing IPCC:AR6/WGII/Chapter-2 (section)

==== 2.6.5.1 Case Study: Assisted Colonisation/Managed Relocation in Practice ====

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Scale: Global

Issue: Helping species move in order to track shifting climate space

Managed relocation (assisted migration and colonisation) is the movement of species, populations or genotypes to places outside the areas of their historical distribution ( [[#Hoegh-Guldberg--2008|Hoegh-Guldberg et al., 2008]] ), and it may be an option where they are not able to disperse and colonise naturally. It requires careful consideration of scientific, ethical, economic and legal issues between the object of relocation and the receiving ecosystem ( [[#Hoegh-Guldberg--2008|Hoegh-Guldberg et al., 2008]] ; [[#Richardson--2009|Richardson et al., 2009]] ; [[#Schwartz--2012|Schwartz et al., 2012]] ).

Individual cases show that assisted migration can be successful. Anich and Ward (2017) extended the geographic breeding range of a rare bird, Kirtland’s warbler, ''Setophaga kirtlandii'' , by 225 km by using song playbacks to attract migrating individuals. Wadgymar (2015) successfully transplanted an annual legume, ''Chamaecrista fasciculata'' , to sites beyond its current poleward range limit, while Liu (2012) found that all but one of 20 orchid species survived when transplanted to higher elevations than their current range limits. After introducing two British butterfly species to sites ∼ 65 and ∼ 35 km beyond their poleward range margins, Willis (2009) observed that both of these populations grew, expanded their ranges and survived for at least the 8 year span of the study.

Butterflies have been favoured subjects for assisted migration in response to regional climate warming, since they are easy to move and their range dynamics have been extensively studied. The Chequered Skipper, ''Carterocephalus palaemon'' , became locally extinct in England in the 1970s, in an area not close to either the species’ poleward or equatorial range limits. Nonetheless, Maes (2019) considers climate a crucial parameter for reintroduction, using SDMs for both choosing the source population in Belgium and introduction site.

The success of assisted migration for conservation purposes has been variable. [[#Bellis--2019|Bellis et al. (2019)]] identified 56 successes and 33 failures among 107 translocations of insects undertaken explicitly for conservation purposes. They concluded that failure was most strongly associated with the low numbers of individuals being released. Another potential source of failure is local adaptation: there is ''good evidence'' that adaptive differences among potential source populations can be important. For example, the transplants of ''Chamaecrista fasciculata'' were more successful when sourced from the most poleward existing sites, while individuals from more equatorial habitats performed poorly even when artificially warmed ( [[#Wadgymar--2015|Wadgymar et al., 2015]] ).

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