• Pioneering conservation research conducted by the University of Sheffield has led to the first successful artificial incubation of Aldabra Giant Tortoises in the Seychelles

• Aldabra Giant Tortoises are a vulnerable species which is known to have a low hatching success in the wild

• The new study shows environmental factors are the main cause of egg failure rather than infertility, shaping conservation strategies for threatened reptile species worldwide

• Scientists have developed a new technique which distinguishes between fertilisation failure and early embryo death in turtles and tortoises

Artificial incubation has led to the first successful hatching of Aldabra Giant Tortoises in the Seychelles, following groundbreaking research that revealed their low hatching success in the wild was not due to infertility.

Last year, scientists at the University of Sheffield developed a new microscopic technique to accurately distinguish between fertilisation failure and early embryo deaths in reptile eggs. The method, previously only used in bird research, was used on turtles and tortoises, providing reliable estimates of fertility in these threatened species for the first time.

In collaboration with conservation teams; Save Our Seas foundation, Nature Seychelles and Fregate Island Foundation, Sheffield scientists analysed five turtle and tortoise species, including both wild and captive populations. The study found that the majority (75 per cent) of undeveloped eggs examined had been fertilised but contained embryos that died at an early stage.

Following these findings, the team on Cousin Island in the Seychelles launched a trial of the artificial incubation of Aldabra Giant Tortoise eggs. This species has virtually zero hatching success in wild nests and is one of only two types of giant tortoise left in the world. The team collected eggs that had failed to hatch showing no sign of embryo development and had been assumed to be unfertilised.

The first batch of eggs hatched last week, marking a landmark success for the trail. These hatchlings not only strengthen the future of the Aldabra Giant Tortoise species but also support the health of Seychelles ecosystems, where tortoises play a vital role in maintaining ecological balance.

Such results also strongly suggest that environmental factors, rather than genetic or maternal problems, are responsible for widespread egg failure in the wild. Researchers and conservation teams can now look more carefully at what these environmental factors may be and how they can be mitigated, leading to more successful wild nests in the future.

Alessia Lavigna, PhD student at the University of Sheffield, and lead author of the study, said: “ Turtles and tortoises are facing an existence crisis. The Aldabra giant tortoises are currently classed as vulnerable, but because they live for so long, population sizes can appear stable even if there is low productivity.

“That’s why it is so important to identify when reproductive success is declining, understand the causes, and step in with conservation interventions like artificial incubation when needed.

“Giant tortoises are highly charismatic and play a vital role as engineers for our ecosystem.”

Dr Nicola Hemmings, from the University of Sheffield’s School of Biosciences, and leader of the research group that undertook the study, said: “The arrival of new hatchlings is a huge boost for the Cousin Island population, which has struggled with almost no natural recruitment for years. This success shows how research can directly drive conservation action, and it will hopefully inspire teams on other islands with low or zero hatching success to adopt artificial incubation too.

“We also believe that these techniques we've developed could be applied to other reptiles such as crocodiles and snakes, opening new possibilities for tackling reproductive challenges in other threatened species.”

The research was carried out in both the Seychelles and the UK by Alessia Lavigne, the first Seychellois scientist to conduct research on Cousin Island, a nature reserve protected under Seychelles law.

The project was made possible through close collaboration with conservation partners, including the Marine Conservation Society Seychelles, Save Our Seas Foundation, Seychelles Island Foundation, Island Conservation Society, Nature Seychelles, Olive Ridley Project, Frégate Island Foundation, and North Island Company Limited. These partnerships enabled the testing and verification of fertilisation rates in threatened turtles and tortoises, initially for species in the Indian Ocean but now with potential for application worldwide.

For more information about studying at the University of Sheffield’s School of Biosciences please visit: https://sheffield.ac.uk/biosciences