A study on Heron Island found that relocated nests differed from nests left in place even when their average incubation temperatures were similar.
Researchers compared green turtle nests left in place with nests moved to shaded or unshaded sites on Heron Island, Queensland, during two nesting seasons. They measured incubation temperatures, hatching and emergence success, hatchling characteristics and performance.
Unshaded relocated nests became warmer, particularly during the last two weeks of incubation. The resulting hatchlings were smaller, had more mass relative to their size and were less able to right themselves. Yet shaded relocated nests and in situ nests had similar incubation temperatures while still differing in hatching success, hatchling size and self-righting ability.
How relocation changed hatchlings
Green turtle clutches were assigned to three treatments: nests left in place, shaded relocated nests and unshaded relocated nests. Unshaded relocated nests had higher incubation temperatures than the other two groups, especially during the final two weeks of incubation. Hatchlings from these warmer nests were smaller, had greater mass relative to their size and performed worse in self-righting tests.
Nests left in place and shaded relocated nests had comparable incubation temperatures, but they still differed in hatching success, hatchling size and self-righting ability. This indicates that relocation was linked to developmental differences beyond those associated with average incubation temperature. The study also assessed emergence success, sex ratio and crawl speed, but the abstract does not report specific results for those measures.
Evidence and caveats
The study assigned green turtle clutches to in situ, shaded relocation or unshaded relocation treatments on Heron Island, Australia, across two nesting seasons. Researchers measured incubation conditions, hatching and emergence success, sex ratio, hatchling size and mass, and two movement abilities. The abstract does not report the number of clutches, effect sizes or statistical details. Because the work was conducted at one island over two seasons, its results may not apply in the same way to other nesting sites or conditions.
