Reptiles
Fiji Crested Iguana
Brachylophus vitiensis · also called fiji crested iguana
The Fiji crested iguana is a spectacular emerald-green lizard, crossed with narrow white bands and edged with a low spiny crest, that lives on just a few small dry-forest islands in western Fiji. It was discovered when a scientist spotted an unfamiliar iguana in a 1980 film, and its eggs take up to nine months to hatch — the longest incubation known in any lizard.
Overview
The Fiji crested iguana survives on a handful of small islands in western Fiji, with the uninhabited sanctuary island of Yadua Taba holding most of the population. It reaches about 75 cm including the tail, bright green with two or three narrow white bands and a low crest. It eats leaves, fruit, and flowers of dry-forest trees, rarely coming to the ground.
The longest lizard incubation
The female lays three to five eggs in a soil burrow, and they take about 7 to 9 months to hatch — timed so the young emerge at the start of the wet season, when fresh plant growth provides food.
Colour and discovery
A calm iguana is vivid green for camouflage; a threatened one can turn almost black. The species was recognised after a herpetologist noticed an odd iguana in scenes of the 1980 film The Blue Lagoon, shot in Fiji, and it was described in 1981.
Status
The Fiji crested iguana is Critically Endangered, with a population in the low thousands and falling. Fire and clearing have destroyed most of Fiji’s dry forest, goats browse the regrowth, and rats, cats, and the invasive green iguana prey on, compete with, or threaten to hybridise with it. Conservation centres on the Yadua Taba sanctuary, predator removal, captive breeding, and controlling the green iguana.
Fiji Crested Iguana: common questions
How was the Fiji crested iguana discovered?
The species was hiding in plain sight. In 1979 the herpetologist John Gibbons was watching the 1980 film The Blue Lagoon, which had been filmed on location in Fiji, and noticed an iguana in some of the scenes that did not match the previously known Fiji banded iguana. Follow-up fieldwork in the Fijian islands confirmed it was a separate, larger, crested species, and it was formally described as Brachylophus vitiensis in 1981. It is one of the more famous cases of a vertebrate being brought to scientific attention through a movie.
Why do the eggs take so long to hatch?
At around seven to nine months, the Fiji crested iguana has the longest known incubation of any lizard, and the reasons are not fully settled. The eggs are laid in a burrow in the soil during the dry season and develop slowly through cool conditions, hatching at the start of the wet season when new plant growth provides food for the young. A long incubation may be an adaptation to time hatching precisely to that flush of food and rain, and it may also relate to the iguanas' ancestors having colonised Fiji across a vast stretch of the Pacific, possibly on rafts of vegetation, a journey that would favour tough, slow-developing eggs.
How did iguanas end up in Fiji at all?
Iguanas are otherwise an animal of the Americas and the Caribbean, so the presence of a small group of them in Fiji and Tonga, thousands of kilometres away across the Pacific, is a long-standing puzzle. The leading idea is that the ancestors of the Pacific iguanas rafted across the ocean from the New World on floating mats of vegetation carried by currents, an extraordinarily unlikely event that need only have happened once. Once established, they diversified into the few species found in Fiji and Tonga today, of which the Fiji crested iguana is the largest and most striking.
What is being done to save the Fiji crested iguana?
The core of the effort is the island of Yadua Taba, which was set aside as a sanctuary, cleared of goats, and managed with careful fire control to let the dry forest recover, and which now holds most of the world's Fiji crested iguanas. Other work includes removing predators and invasive plants from additional islands, captive breeding at facilities in Fiji and overseas, translocating iguanas to restored islands, monitoring populations, and trying to control the spread of the invasive green iguana, which threatens the native species through competition and disease. Fiji has also given the species legal protection.