New research shows a lack of ultraviolet light and a poor diet is contributing to the bad health of some captive tuatara.
Massey University undertook the research with Wellington Zoo to discover why tuatara kept indoors are suffering from poor bone density and twisted spines while those in the wild are not affected.
The study of about 200 captive tuatara found a lack of UVB light and a diet very low in calcium and high in phosphorus is causing problems for the New Zealand reptiles.
Massey senior lecturer in avian and wildlife health Brett Gartrell says that often the lighting wasn't right for the captive tuatara.
"Many of the keepers were trying to do the right thing - they're using lights that are recommended for reptile use.
"But when we actually took direct measurements of UV output by those lights, we found either that they were not producing enough UVB light at the source, or that they were too far away from the tuatara for them to actually get any benefit."
Dr Gartrell says captive tuatara in the study showed metabolic bone disease and the young reptiles had fractured jaws and spinal deformities. This is also affecting fertility, as some tuatara are finding it hard to lay eggs.
The study recommends brushing captive tuatara's food with a calcium powder and increasing their exposure to ultraviolet light.
Dr Gartrell says institutions that keep tuatara in New Zealand and overseas have been made aware of the study and its suggestions.
