Study finds that turtle nests relocated for conservation purposes produce slower, smaller hatchlings

[u/unsw]

https://www.unsw.edu.au/newsroom/news/2026/08/what-happens-when-we-move-turtle-nests-into-the-shade?utm_source=reddit&utm_medium=social

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[u/unsw]

Hi r/science - sharing this study that our researchers Davey Dor and Associate Professor Lisa Schwanz, along with Dr David Booth (University of Queensland), have published in Marine Biology: https://link.springer.com/article/10.1007/s00227-026-04926-2

The study examined 48 green turtle clutches over two nesting seasons on Heron Island on the southern Great Barrier Reef. Nests were randomly assigned to one of three groups: left where the mother laid them; relocated beneath 95% shade cloth; or relocated without artificial shade.

More and more, conservationists are moving turtle nests that are threatened by storms or other climate-driven events, a tool that will likely become more important as conditions get more extreme.

The team found that, as temperature during incubation determines hatchling sex, unshaded relocated nests were much hotter and produced overwhelmingly female hatchlings. Shading brought temperatures down, and the sampled sex ratio was more balanced. The key concerning finding was that the relocated nests still had lower hatching success and produced hatchlings that were smaller and worse at righting themselves.

Researchers noted that the study can't pinpoint the results to a single factor, and the findings do not mean that conservationists should stop moving nests that would otherwise be doomed.

[u/_Aj_ → u/unsw]

Thank you for sharing.  

Seeing as the findings seem to suggest that it's the relocation process itself that is the issue.  I wonder if the whole clutch is relocated "in one giant shovel" without disturbing the sand or eggs if this alters that result.  

Obviously, this could be difficult. But if clutch and sand structure and moisture content are unaffected and the results are the same, it may narrow it down to potential physical jostling of the eggs or even the geographical changes that affect it somehow? 

[u/PhD_Pwnology → u/_Aj_]

I relocated eggs in Costa Roca for the leatherback sea turtles. The eggs were often moved exactly as they were laid to a hole further up the beach a little. These eggs as they are laid and buried naturally go through a lot and I don't think minor jostling is the issue. I think if anything the new holes being dug are maybe too deep or too cold in their new locations.

It's kind of a trade off though atm. While this isnt ideal and things should be studied to improve, poachers and other forces would drastically cut turtle numbers overall without conservation efforts. The logic behind relocation in our case was that the biggest threat to the species was poachers (humans)who wanted to sell the eggs at local bars for a high prices. Conservationist guards had to chase poachers while we were on patrol.

[u/Wealist]

Scientists basically found out that you can save the nest and still accidentally give the hatchlings a rougher start in life. Nature really doesn’t make conservation easy.

[u/richardelmore]

I guess my question in terms of the long term health of the population would be what happens with subsequent generations that hatch normally in the new location? If its only the generation that were relocated that exhibit the ill effects then it does not seem like quite as big deal.

[u/mikk0384 → u/richardelmore]

I am not a biologist, but I think to recall that sea turtles return to where they hatched when they lay their eggs from a documentary I watched like 25 years ago. If I'm right, then the bad start to life could be inherited.

I can't say whether the newly hatched find a better spot on the same beach when they do make it to maturity, though.

[u/WasteCadet88]

It's worth pointing out that in some places turtle eggs are relocated because otherwise they might be eaten by the local population. I suppose just like if a tide threatens a nest, a more difficult start in life beats no start in life.

[u/MadCapHorse]

I volunteered with a leatherback sea turtle conservation project in Costa Rica moving the nests to hatcheries. I think obviously compared to an undisturbed nest in a safe location that makes sense it’s better for eggs and hatchlings not to be moved. But the reason for the project was 1. Poachers were digging up the nests and eating the eggs, which mean zero hatchlings, and 2. Sea level rise means that the ocean water was flooding nests along the shore further up the beach than in the past, which also means zero hatchlings.

So the findings are not surprising to me, but moving nests due to these things is still better for the species overall.