Issuu

Photo: Malcolm de Raat

Tuatara survey for 2023: plentiful reptiles become bigger, bolder and more colourful

Malcolm de Raat and Roger Wallace told those attending their recent reptile presentation that tuatara are not lizards, but descendants of dinosaurs... and there are some robust specimens on the Island. Take a walk on Tiritiri Matangi at night and you’re likely to both surveys and anecdotal evidence showed tuatara were see a tuatara – or 10. Not only has the Island’s population healthy and doing well, there was insufficient scientific data begun to flourish, but the island-born tuatara are beginning to confirm the population was established. to outgrow their parents. The third survey was organised almost 20 years on from The third survey of the reptiles has herpetologists excited. translocation. Over two weeks this March, a group of 22 The largest male found this year weighed more than a dedicated volunteers, led by Graham Ussher, Roger Wallace kilogram – and he is still a youngster. and Malcolm de Raat, scuttled around the Island by night A short 20 years ago, October 2003, Dr Graham Ussher and day, searching for the reptiles. One bite and several and a team of very enthusiastic volunteers translocated 60 scratches later they amassed 104 total tuatara captures, tuatara (20 males and 40 females) on to Tiritiri Matangi and comprising 76 unique individuals in a range of sizes and released them in four separate sites across the colours, including some absolute whoppers. northern half of the Island – 5 males and 10 Of the 76, 10 were founder animals and Tuatara are the females at each. the other 66 all born on the Island and, by sole survivors of a These tuatara originated on Atiu Island (aka definition, no more than 19.5 years old. chain of dinosaurs Middle Island, in the Mercury Island group). On release, founders were estimated to be known as “beak Most reptiles of this size live in very warm between 20 and 40 years old, which means heads”, the countries. Most New Zealand reptiles are either they are now between 40 and 60 years rhynchocephalians, crepuscular (that is, appearing or active at old. Living on Tiritiri Matangi has clearly genus Sphenodon. twilight) or they are nocturnal. This, combined been beneficial as all founders caught are Fossil records with our temperate climate, means our reptiles now heavier and longer than their release suggest they have to operate at much lower temperatures; statistics. The largest founder tuatara have had little for tuatara, this is as low as 12-15°C. captured were a male at 815g, measuring anatomical change The originals, or founders, were all suitably 531mm long (SVL – or snout to vent length – in 170 million years. weighed, measured and injected with a 280mm), and a female at 590g, 435mm long glass-encapsulated PIT (passive integrated (SVL 260mm). transponder) tag. When a tuatara is caught as part of a The real eye openers are the island-born tuatara who have survey on Tiritiri Matangi, a tag reader is used to scan the had a great start to life on Tiritiri Matangi. Remembering they tuatara and display its tag number, if it has one. This allows are no more than 19.5 years old, the largest Island-born us to identify the founder individuals. tuatara captured were a male at 1100g, 642mm long (SVL In 2009 and 2015, surveys were carried out to see how the 297mm), and a female at 495g, 430mm long (SVL 250mm). post-release tuatara population was faring. The 2009 survey The youngest and smallest tuatara captured was a juvenile, captured 30 individuals, including 24 founders. In 2015 the estimated to be one to two years and weighing in at 80g, survey captured 31 individuals, including 22 founders. While 295mm long (SVL 140mm).