UBC review: no frogs or reptiles moved for construction formed a lasting population

Moving frogs, snakes, turtles and other reptiles and amphibians out of the way of construction almost never produces a population that lasts, according to a global review led by the University of British Columbia. Across the cases the team examined, not one development-driven relocation established a population that could survive and reproduce on its own.

The review, published in Conservation Biology, covers 313 translocations of 163 species reported between 2007 and 2023. UBC announced it on October 28.

Two kinds of moving day

The researchers split the cases by motive. Some animals were moved for conservation, to restore a species to a place it had vanished from. Others were moved as mitigation: cleared off land so that a road, housing project or other development could go ahead.

The outcomes diverged sharply. Only 6% of development-related relocations showed population growth, compared with 19% of conservation relocations that showed growth or the potential to persist. Mitigation moves failed about twice as often as conservation moves, according to the authors.

Success was scored in stages, from whether animals survived the move at all to whether they eventually formed a self-sustaining group. The mitigation cases stalled before the last step every time.

What the successful moves did differently

Two practices were most closely tied to good outcomes: dealing with whatever threatened the animals at the release site before they arrived, and monitoring them for longer afterward.

That second point is where the review meets a problem closer to home for the authors. A separate UBC study earlier in 2026 counted about 5.1 million amphibians and reptiles moved under development permits in British Columbia over the four years from 2019 to 2022. Nobody was required to find out how many lived.

"Without adequate follow-up, we won't know whether animals survive in their new location," said lead author Megan Winand, lab manager of UBC's Conservation Decisions Lab.

Habitat first, moving last

The authors argue that relocation is being used as a default when it should be a last resort. Their recommendation is to protect habitat in the first place, and to treat moving animals as a measure that needs evidence and follow-up rather than a box to tick before construction.

The release does not say how many of the reviewed mitigation cases had any long-term monitoring at all, which limits how much the 6% figure can reveal. What happens to the millions of animals already moved in British Columbia is still unknown.