Fiji crested iguana

Taxonomy and etymology

The generic name, Brachylophus, is derived from two Greek words: brachys (βραχῦς) meaning "short" and lophos (λοφος) meaning "crest" or "plume", denoting the short spiny crests along the back of this species. The specific name, vitiensis, is a Latin adjective derived from the Latin word for Fiji.

The species is closely related to the Fiji banded iguana and B. bulabula. The genus Brachylophus has been suggested to be the descendants of a more widespread lineage of (now extinct) Old World iguanids that diverged from their New World relatives in the Paleogene. Alternatively, the ancestors of these iguanas may have rafted 9000 km west across the Pacific Ocean from the Americas, where their closest relatives are found.

The discovery of Brachylophus vitiensis began when Dr. John Gibbons of the University of the South Pacific was invited to the screening of the movie The Blue Lagoon. The director filmed part of the movie on a remote island and included shots of the native wildlife to enhance the feel of the movie, including a large colorful iguanid. Gibbons, who had been studying the Fiji banded iguana at the time, travelled to the island and identified it as a distinct species.

Habitat

B. vitiensis is found on the islands of Fiji, in the South Pacific. The species is restricted to tropical dry forests, specifically to the rain shadow forests located on certain islands in Fiji. These forests are one of the most threatened vegetation types in the Pacific. A small population of the Fiji Crested Iguana – less than 80 individuals – can be found on the small island of Macuata. The majority of this species – less than 4000 individuals – is most commonly found on the island of Yadua Taba. The island is a National Trust of Fiji reserve, and is thus the only legally protected population of the Fiji Crested Iguana. The island is now also free of forest burning and the presence of goats, which was a major factor in the initial decline of the species. There are six other Fijian islands where evidence of the species has been recorded: Deviulau, Waya, Mouriki, Monu, Qalito, and Malolo Levu. The population on Malolo Levu seems to be an intermediate of Brachylophus vitiensis and Brachylophus bulabula likely resulting from hybridism in the past. Brachylophus bulabula has been found on neighbouring Mana Island and nearby Viwa Island and there likely was some degree of overlapping of the two species in this area. There also have been hybrids of the two species produced in captivity. The species could have inhabited land that was 500 meters above sea level in the past, but is currently found at 100 meters or less above sea level.

Description

The Fiji crested iguana is a large stocky lizard distinguished from the Fiji banded iguana by the presence of three narrow, cream to white colored bands on males, rather than the broader bluish bands of the latter species. These whitish bands often have chevrons of black scales close to them. Brachylophus vitiensis is distinguished by its larger size growing to 75 centimetres (30 in) in length and weighing as much as 300 grams (0.66 lb). It is further distinguished by the presence of a taller spiny "crest" on its back with spines as long as 1.5 centimetres (0.59 in) running from the nape of the neck to the base of its tail.

When Fiji crested iguanas first hatch from their eggs they are dark green, but after several hours their skin becomes bright emerald green and narrow white bands can be seen along their body. Their eyes are reddish orange or pinkish gold in color.

Behaviour

The Fiji crested iguana is a diurnal creature that tends to live under the shade of trees and will seek sunlight/heat on days with cool temperature. It has the ability to rapidly change colour from green to black when aroused.It uses this ability when threatened by any potential predator in its surroundings. These colours will vary depending on the severity of the situation, bright green is standard, dark green would be slightly dangerous, and black would be an extreme. If its white bands or its sudden change in colour has not intimidated its predator, it will ultimately resort to an expansion of its neck, a bobbing of its head, and it will pounce itself towards the potential threat. In order to move from tree to tree where it usually resides, it uses the overlapping branches in order to move effectively through their environments. Their long toes and tails help them keep balance while they move through the trees.

Diet

Fiji crested iguanas are predominantly herbivorous feeding on the leaves, fruits, shoots, and flowers from trees and shrubs. These iguanas eat both the new leaves and the large flowers from trees and shrubs. Hence, it is restricted and limited to tropical dry forests and similar habitats on islands in western Fiji. Furthermore, the Fiji crested iguanas particularly have a preference for sweet hibiscus flowers of the Vau tree (Hibiscus tiliaceus). The vau tree is one of the species of trees where they spend most of their time residing. Fiji crested iguanas do not display any major or significant seasonal shifts, sex differences, or age-class differences in their diet patterns. Moreover, scientists have observed captive hatchlings even eating insects; nonetheless, adults will not.

Reproduction

The Fiji crested iguana, similar to all other iguanas, reproduces by laying eggs.The breeding season takes place between March and April, with courtship and mating commencing in January. Fiji crested iguanas lay large white eggs, which have a leathery texture.The Fiji crested iguana is oviparous and has one of the longest incubation periods of any reptile, which can last from 189 days to nine months. Female iguanas are usually found defending the eggs and guard the nest of four to six eggs. Females dig holes on the forest floor, where three to five eggs are laid and they then fill the hole or burrow. The eggs are white and leathery, with the average number of eggs in a clutch being four
The eggs take roughly 8–9 months (October–November) to hatch and this occurs at the beginning of the wet season. A few of weeks prior to hatching, a brown oval mark arises on the surface of the egg. This oval mark identifies the spot where the baby iguana's head will pop out of the egg. Sometimes, a full day can pass before the Fiji crested iguana hatches from the egg. After hatching, the baby iguanas obtain moisture by licking wet leaves.

Folklore

The Fijian name for iguana is "vokai", although some tribes call it "saumuri". Two tribes regard the iguana as their totem and as such its name is not allowed to be mentioned in the presence of women or the offender may be beaten with a stick. The majority of Fijians, however, are terrified of the crested iguana because of its behavior when threatened.

Threats

The biggest threat this iguana faces is habitat loss due to fires, storms, agricultural development, and competition from feral goats. Goats were introduced to Yadua Taba in 1972 and numbered over 200 by the late 1970s. The vegetation on the island during this time was severely depleted by a combination of grazing and fires used to drive goats for ease of capture. After the discovery of the Fiji crested iguana, the island was declared a sanctuary and all but a few goats were removed and fires banned. As a result, the dry forest on the island has recovered to a great extent and is the best remaining example of Pacific dry forest. Invasive Leucaena trees threaten the regeneration of native food trees for the iguanas, but the government of Fiji has taken steps to eradicate the trees.

A secondary threat is introduced predators in the forms of rats, mongooses, and cats which prey on the iguanas and their eggs. Additionally the iguana has been hunted as a food source and for the illegal animal trade.

In 2002, five adult iguanas were stolen from the sanctuary, but Fiji Custom officers caught the smuggler before he boarded his international flight. Since this incident, tourist visits to the sanctuary have been prohibited and only researchers are permitted to visit the island. In order to protect iguanas in the sanctuary from diseases and parasites, it is not permitted to return to the island any lizard that has been removed.

Conservation

Due to the removal of the goats, forest area was increased by 10%-20% since 1980, which means more resources for the iguanas and a larger environment. There are many other recommended actions that should be taken in order for them to survive. The highest threat against the Fiji Crested Iguana today is predation by other animals such as the feral cat, rats, and mongoose. Physical measures should be taken to protect the iguanas from cats and mongoose, which should include removing them from the area similar to the removal of the goats. Also, the only island being monitored is Yadua Taba Island. Other islands that inhabit Fiji Crested iguanas such as Macuata, Monu, and Monuriki should also be monitored. Another action that should be taken is reforestation. The iguanas need more resources in order to repopulate, which means there should be more food trees that should be planted on the island for them to feed off of.

However, the available data on this species is fairly limited. There is little data on “the effects of direct or indirect factors potentially responsible for causing the population crash.” Without some detailed data on that topic, “any Species Recovery Plan developed is not likely to be cost effective and may fail to achieve the desired results.”