BACK FROM THE BRINK

How captive breeding projects have helped save the Chinese crocodile lizard.

The Chinese crocodile lizard (Shinisaurus crocodilurus) is one of the rarest lizards on the planet and the last remaining species of Shinisauridae, a family that has been on planet Earth for over 250 million years. Surveys in 1978 identified the species as critically endangered with subsequent surveys discovering that population numbers hit less than 950 individuals in 2014. During that time, the largest population held no more than 350 lizards and the smallest, no more than 10.

With a range comprised of tiny pockets of South China and North Vietnam, the species is under serious threat from deforestation. The broken pockets of remaining habitat also became the focus of illegal harvesting for traditional medicines as well as the pet trade. In fact, there are now thought to be more Chinese crocodile lizards in captivity than there are in the wild. However, the combined efforts of habitat protection and captive breeding programmes have now seen a U-turn in population numbers with 2021 welcoming a string of re-introductions to protected nature reserves across the Guangxi province.

Natural history

The Chinese crocodile lizard is a robust, bulky lizard reaching around 40cm in length. Like the name suggests, they have bulbous scales that represent the scutes of a crocodile. Males often exhibit bright red colouring on their throats and bellies, with females being slightly drabber and possessing white stripes down the underside.

There are debates around whether the Vietnamese population should be considered a subspecies (S. crocodilurus vietnamensis). This has been proven and disproven several times in recent years. Regardless, Shinisaurus crocodilurus is considered a ‘remnant reptile’ from the Eocene, with fossils dating back 49 million years. It has remained relatively unchanged throughout this time and thus holds major significance in not just maintaining biodiversity but in better understanding the tapestry of natural history across the globe.

They are a semi-aquatic species that inhabit the densely overgrown banks of slow-moving streams at an elevation between 500-700m. They require branches that overhang waterways of about 24°C, during their active months throughout summer. Their very specific requirements mean there are only a handful of remaining locations where Shinisaurus can be found and habitat protection (particularly that of the waterways that run through them) is crucial to the preservation of the species.

Although the Vietnamese populations of Chinese crocodile lizards are generally active all year round (opting to rest on the cooler days) those in China will hibernate for up to 4 months of the year, meaning that maintaining a steady record of populations can be difficult. However, in Spring and Summer, they are reasonably sluggish and can sometimes spend days basking in the same spot if left undisturbed. Their primary diet is crustaceans, fish, tadpoles, and molluscs but they have been recorded eating frogs and snakes. Furthermore, they can spend up to 30 minutes submerged in water without needing to take a breath.

In their native range, it is believed that these lizards can be a cure for insomnia. When they were first identified as critically endangered, it was reported on several occasions that local people would sell them to tourists at the gates of national parks for between $10 and $20. Since then, their popularity in the pet trade exploded and wild-caught and illegally smuggled individuals can fetch up to $800, the equivalent of 2 months’ salary for most people in the region. In recent years there has been a drastic decline in confirmed illegal exports, which suggests that demand has dropped as captive breeding has increased. The species was protected by CITES Annex 2 in 1990 but was upgraded to Annex 1 in 2017.

Crocodile lizards in captivity

Crocodile lizards have seen a second wave in popularity in captivity but with much less contention. With several European breeders now producing good numbers of these animals in captivity, experienced private hobbyists can contribute to the wider captive husbandry discussion. Although it should be emphasised this is not a species that should be kept as a ‘pet’, private breeders can now support conservation without damaging the already fragile wild population.

Michael Zollweg is the ESF Studbook Holder for Shinisaurus. This means he manages the data records for people and zoological institutions keeping the species to help maintain good genetics, as well as orchestrating communications with conservation projects in China. Michael told Exotics Keeper Magazine: “The ultimate goal is to expand knowledge of the species and share experiences, especially with in-situ projects. Ultimately, a wellconstructed ex-situ breeding project at least ensures the conservation of the species, albeit in a non-ideal way, which must always be coupled with habitat conservation.” Currently, the studbook has around 40 individuals and organisations linked to the wider breeding programme and whilst this is unlikely to include every keeper in Europe, it provides a good picture of the captive population.

Michael believes that without captive breeding projects, the recovery from near-extinction of this species would not have happened. He added: “Ex-situ breeding projects could make an important contribution to further initiatives for the conservation of Shinisaurus. First of all, it is important that these are projects in which a large number of participants take part (whether private individuals or zoological institutions) to exchange information with each other when necessary and seek contact with in-situ initiatives. In-situ projects lead the way in that they can provide the most important parts of species conservation, which is the preservation of specific habitats and on-the-ground education. For Shinisaurus, this has been achieved in an exemplary manner in China.”

Reintroductions

Although much of the crocodile lizard’s native habitat is still under immense pressure, the Luokeng Nature Reserve in Guangdong and the Guangxi Dagushan Crocodile Lizard Nature Reserve have both seen populations supplemented with captive-bred individuals over the last 5 years.

At the Luokeng Nature Reserve, decades of hard work have managed to boost numbers of the Chinese crocodile lizard exponentially in recent years, with a 30% increase since 2012. A total of 150 lizards have been captive-bred and released in the region since they were discovered there in 2009.

Researcher, Liu Haiyang told China Daily “the first batch of released reptiles are in good condition and have grown into adults. We’ve even found that they’ve reproduced, which is a good indication of the success of the reintroduction. We’ve shifted our focus from genetic rescue to maintaining its population as the number of Chinese crocodile lizards has been on an upward trend. The main purpose of artificial breeding has also changed from reintroduction to scientific research.”

This year, researchers at the Guangxi Dagushan Crocodile Lizard Nature reserve have also released a further 15 animals into a new habitat which hopes to pave the way towards creating a new population in the province. They are currently using radio telemetry devices to track the released animals and gauge the suitability for further releases.

Michael continued: “The initiative for a successful ‘lighthouse’ in-situ breeding project in China was taken in 2011 by a private European keeper and breeder of Shinisaurus in co-operation with scientists from Guilin, China. At present, the breeding program consists of two large breeding stations, each with around 30 optimally equipped outdoor terrariums. Offspring from this breeding project were released into the wild for the first time in 2020. A great deal of work was necessary in the run-up to this. Among other things, new suitable habitats had to be found, genetic analyses of the animals had to be carried out on-site, and training courses had to be held for the staff in charge of the breeding stations. During the genetic analyses, for example, samples of about 80 Shinisaurus were taken from the stocks of the members of the ESF studbook to analyse genetic correlations. On-site training has also been conducted. Meanwhile, the habitats have been combined into a contiguous national park established specifically for Shinisaurus.”

With such dedicated conservation efforts from breeders across the world as well as researchers and conservationists in China, the future is looking much brighter for the Chinese crocodile lizard. As with any conservation initiative, longevity is often the hardest challenge. But, with this prehistoric creature now widely celebrated by local communities and volunteers, as well as a good population in captivity and scope for them to breed in the wild, many of the components required to support this species are in place.

The role of private keepers

For many keepers, particularly in the UK and Europe, herpetoculture can sometimes feel disconnected from global conservation efforts. However, much of the information required to breed endangered species comes from collective knowledge from both zoos and private keepers. Providing that all animals are sourced legally and responsibly, private keepers have an often-unrecognised impact on the conservation of many species.

“Absolutely, I believe that private breeders can support accredited breeding projects” explains Michael. “Many initiatives, for example, to study the behaviour of Shinisaurus (now more than 100 different behaviour patterns such as courtship, mating, intraspecific aggression) are based on observation by ex-situ keepers. Valuable help can be provided, for example, in genetic studies and in the discovery and treatment of diseases.”

It is vital that more people, particularly those that keep endangered species, share their knowledge with the wider herpetoculture community. Although Chinese crocodile lizards, like many endangered species, should be considered a very specialist animal to keep, those that are working with other species can still provide huge value by sharing their observations. Networking with local groups, online forums, researchers, and studbook holders could support the conservation of an entire species. Conservation is often only possible when pools of knowledge are created and while much of this will be in the country of origin, some will be spread across international laboratories, universities, zoological facilities, and private collections. Keeping records of exactly how we maintain our animals is extremely important and may one day be extremely valuable to the preservation of a species.

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