Fijian Iguana

In 2005 the IIF awarded a grant to Peter Harlow and Suzanne Morrison to study the conservation biology of the Fijian crested iguana, Brachylophus vittensis. The grant provided important support to the ongoing natural history study that will help answer questions regarding the ecological role this iguana play in their native forests. The following is excerpted from a report that Suzanne recently provided from the field:

The marked decline in Fijian crested iguana numbers over the last 15 years has resulted in their critically endangered status and in the precarious situation where 90% of the entire species population is confined to a single tiny (70 ha) island, Yadua Taba. Fijian crested iguanas inhabit tropical dry forests, a habitat which in itself is globally threatened. Little is known of the biology or requirements of crested iguanas in their natural habitat and our aim to collect basic biological information. This is a vital step in the Iguana Specialist Group’s (ISG) Species Recovery Plan for this iguana that will hopefully lead to the reintroductions and translocations necessary to establish stable populations on other islands.

A mark recapture study within was initiated in 2005, and 265 iguanas have now been fitted with PIT tags including 45 hatchlings. These individuals will continue to be surveyed over the course of the project to obtain demographic data and identify seasonal and annual variations in habitat use and community structure. During recent fieldwork, in February 2006, many gravid females were captured resulting in the first information on Fijian crested iguana nests in the wild being recorded. As a result 14 nests are being monitored for the duration of incubation to establish environmental parameters for successful hatching. Each nest has been fitted with a thermachron iButton to record nest incubation temperatures in the field. The February 2006 field trip also provided an opportunity to obtain additional data on some potential threats to the islands’ iguana population, namely the Pacific rat and the yellow crazy ant. Common throughout Fiji, the Pacific rat is the only terrestrial mammal on the island and is suspected of having a large impact on the ecosystem.

The importance of Peter and Suzanne’s work on Yadua Taba cannot be overstated. If we are to successfully distribute the population of Fijian crested iguanas so as to establish them on additional islands, then it is vitally important that we understand the habitat characteristics required to support them. The current “all eggs in one basket scenario” is risky and tenuous. Additionally there are a few other drastically reduced populations of crested iguanas clinging to existence on small islands and plans call for these to be rescued. This could entail feral mammal eradication, habitat restoration or captive breeding programs to preserve the genetics of these remnant populations. For additional information, view The Fijian Crested Iguana Project website.