This past January Jonathan Choquette, lead biologist for the OPRREC program, was visiting the beautiful country of New Zealand for a conference. While he was there he took a day trip to the Orokonui Ecosanctuary – a 307 ha fenced predator-free wildlife sanctuary.
The view from the visitor centre at the Orokonui Ecosanctuary in the Otago region, New Zealand.
Entry Permit #713 in hand, we are ready to enter the sanctuary! Getting into this place is no easy feat: an 8.7 km long 1.9m (6.2 foot) tall fence – designed to keep out even the smallest of intruders (baby mice!) surrounds the entire sanctuary. The only way in is through the double-locked security gate, and with the right passcode…
The entry gate (left) and perimeter predator-resistent fence (right) at the Orokonui Ecosanctuary.
This community-led conservation venture is aimed at protecting, managing and enhancing some of New Zealand’s most significant habitat and species. The predator resistant fence ensures invasive introduced mammals stay out – thus maintaining Orokonui as a safe haven for some of New Zealand’s (and the world’s) rarest wildlife. Of most interest to me of course, were the reptiles: Tuatara, Green Skink, Otago Skink, and my favourite, the Jewelled Gecko (Naultinus gemmeus), call this place home.
An outdoor display enclosure featuring dozens of globally endangered Otago Skinks (Oligosoma otagense), at the Orokonui Ecosanctuary.
The globally rare Jewelled Gecko (right) is only found on New Zealand and is restricted to the southeast portion of the South Island. The IUCN considers it to be Endangered globally. I mentioned this was my favourite of the resident reptiles because I am just amazed by the beauty of these creatures (stunning green and white), and also because I had previously read about a very interesting reintroduction project with this species at Orokonui.
Written by C. Knox and J. Monks and published in the journal Animal Conservation in 2014, the team outlined the successful use of a soft release technique using penning to reduce dispersal of the lizards following translocations to the sanctuary.
‘Soft release’ generally entails measures used to ease the translocation of animals to a release site (moving to a new home can be stressful!). Whereas ‘hard-releases’ provide no such measures.
Essentially what Knox and Monks did was translocate 53 geckos of various ages to Orokonui, all of which were rescued from a location threatened with illegal collection for the pet trade. Forty-two of those animals were penned for 9-10 months, and eleven were released outside of the pen, ~200m away.
The penned animals were confined to an enclosure created within the ecosanctuary (think, fence within a fence) which essentially restricted the dispersal of the animals. The idea was to habituate the lizards to their new home by encouraging them to form new associations with the landscape and establish new home ranges. The pen was made from 0.5m high polyethylene plastic and covered an area of ~650 m2. The authors then followed a subset of 19 adults with radio transmitters (made in Canada by Holohil!) for three weeks in the spring. Half were from the pen and the other half were from outside the pen. Radio tracking began in 2012, immediately after the penned group was set free (when pen was removed), which occurred at the same time that the unpenned group was released.
A Jewelled Gecko (Naultinus gemmeus) on display during the World Congress for Herpetology at the University of Otago. This diurnal, cryptic and arboreal gecko blends readily into its forest home. They are long-lived and give birth to at most two offspring per year.
So what happened?
Well, interestingly, the area occupied by the group of penned animals did not increase once the pen was removed. Those lizards all pretty well stayed put.
In contrast, the unpenned geckos bolted from the release site, and the area occupied by that group increased by over 4 times in just 3 weeks! That’s because the unpenned animals moved up to 40m outside of their release area – not much by human standards but we’re talking about a 16 cm long (max.) gecko here!
And this is really important because when trying to establish a new population of lizards, long-distance dispersal from a release site can have devastating consequences; if lizards disperse too far then they may never come into contact with other released lizards and therefore will fail to establish a breeding population. Case in point: all four females found at the original penned site during surveys the following year were pregnant, whereas neither of the two females found at the unpenned site were.
Jewelled Gecko outreach display at the Otago Museum, in the City of Dunedin, telling the story of two geckos illegally smuggled out of the country for the pet trade.
Not convinced the author’s had a large enough sample size to be confident in the results? Well, you can sleep soundly tonight knowing that a follow-up study published in 2017 further validated the 2012 results (again by C. Knox and J. Monks, now with a couple of colleagues). This time the authors studied 69 geckos and conducted a similar penning experiment but at a different site (outside of Orokonui), in a different season (winter as opposed to spring), and for different lengths of time (penned for 4 vs. 9 months). The important finding here was that penning for 4 months was just as effective at reducing dispersal as penning for 9 months.
Work at the Orokonui Ecosanctuary has contributed a seriously important advancement to the reintroduction biology of this species. Consider for a moment that 9 translocations with Jewelled Geckos and their close cousins (i.e., geckos of the Naultinus genus) had occurred in NZ prior to the 2012 study – all using “hard releases” (no pens), and all failed to detect more than two released animals after translocation.
Oh, and did I mention that not a single project could confirm whether or not the translocated animals resulted in population establishment. Meanwhile, today the Ecosanctuary website, under a photo of a Jewelled Gecko, proudly claims that “A population of more than 100 is breeding well at Orokonui”…
Hats off to the tireless efforts of those dedicated Kiwi conservation biologists – unafraid to “have a go” at reintroductions when their wildlife is in peril. It may have taken a few attempts over the years with the Jewelled Gecko, but they kept trying and eventually figured it out. I am positive that we could learn a thing or two from the Orokonui “Lizard Pens” and the little jewels of the Otago forests.
-Jonathan Choquette, Lead Biologist – Ojibway Prairie Reptile Recovery
Tramping (aka “hiking” in Kiwi lingo) the beautiful trails of the Orokonui Ecosanctuary.
Note: Orokonui is a not-for profit venture and relies on volunteers and other contributions. You can check them out at www.orokonui.nz. If you’d like to delve deeper into the Jewelled Gecko translocation research, here are the two research papers mentioned in this blog post:
C. D. Knox, S. Jarvie, L. J. Easton, J. M. Monks. 2017. Soft-release, but not cool winter temperatures, reduces post-translocation dispersal of jewelled geckos. Journal of Herpetology 51(4): 490-496.
C.D. Knox and J.M. Monks. 2014. Penning prior to release decreases post-translocation dispersal of jewelled geckos. Animal Conservation 17: 18-26.