Assisted Migration
Assisted migration (sometimes called assisted colonization, assisted range expansion, or managed relocation) is when conservation managers new populations in an area beyond the species current range, usually because they are blocked from accessing that habitat or cannot keep up with climate change. Sometimes this is done with subpopulations to improve genetic diversity (assisted gene flow).
Species blocked by roads and fences are opportunities where manually moving species could unlock the species potential to take care of itself after the barrier is crossed.
Another target are species that can’t move quickly like plants and small bodied animals
It may be a good idea to start moving species to distant locations they would never reach naturally if it benefits the survival of those species. See
Gilbert’s Potoroo. It was abundant for an extended range along the southwestern coast of Australia but has become the smallest population size of any mammal in Australia. A population was artificially established on Bald Island, Middle Island, and in Waychinicup National Park. The native habitat was reduced to 15 individuals and a wildfire reduced that to 7 survivors. On the artificial transplanted island locations there are 100 as of 2018.
The western swamp turtle, also in Australia has had 4 populations (83 turtles total) transplanted 300km to more suitable habitat. As of 2020 growth rates were normal for their natural habitat, although it will take more time to see if survivorship and reproductive rates indicate long-term success.
Torreyey Pine, an evolutionarily distinct species has plans to be moved from Florida to North Carolina, a distance of at least 300 miles.
It seems like we can successfully do this for highly endangered species and/or species without futures, if we can put aside the “naturalness” (and fairness) of taking these conservation actions. Unpopulated islands are a limited resource, but the western swamp turtle is an example of simply finding suitable habitat, wherever it may be, and moving the endangered species to it.
Generally, addressing one species at a time is prohibitively resource intensive. So, assisted migration for keystone species would be the logical target.
Biodiverse mediterranean habitat can be especially drought threatened and especially evolutionarily distinct from gondwana relics. They would thus be good targets for multiple instances of assisted migration. For example, Proteas (flower group) of South Africa fynbos lives in nutrient poor soil that favors other gondwana relics and co-evolved gondwana invertebrates. The fynbos species are highly threatened including Proteas. In Australia there are Banksia species in a similar situation. Porteas and Banksia have important effects on their soil and environment which would be useful for other species to adapt as well. Banksia are important food sources for birds and insects. They can be grown at scale in facilities, but the facilities do need specialized conditions. They can be planted with 50%-75% success rates within the first 2 years.
A group that is working on this task is the Big Scrub Rainforest Conservancy in Australia. They are working with a Godwana rainforest remnant in eastern Australia. (A region with high evolutionary distinctiveness.) They are carefully monitoring the isolated remnant genetic diversity of endangered and keystone rainforest trees, and working on a long term plan to revegetate private land with these species. “...long-term sustainability for discrete, sustainable translocation recovery plantings of the genetically optimal threatened species.”
Assisted Migration has a few cases of win-wins. Coastal wetland can be migrated inland to preserve habitat that is often important nurseries for fish and bird migrations while also protecting people from storm surges. Coastal wetlands are extremely good for biodiversity as massive sources of nutrients and life stages. Techniques for doing this include adding sediment from dredging, planting vegetation to trap sediment, diverting inland streams to deposit silt, and simply removing tidal barriers to allow inland flooding.
For further reading, see this 2023 global evidence map of assisted migration.
Overall, this intervention feels likely to be effective, as long as it targets keystone species. I would not advocate for assisted migration as a generalized tactic.* It would be primarily keeping a habitat and supporting the many species that use it. Trees and other habitat modifying plants would be the obvious target. They are easy to move as a sprout and are important underlying fabric for future generations. It seems like something we should be willing to do more often than we currently are, once again because environmental groups are averse to active modification. This would be addressing both endangered species, endangered habitats, and having an outsized effect by using keystone species while also relying on already practiced techniques.
*unless I learn of a more efficient method than carefully moving individuals a few at a time, as seems to be the current practice.