Species Information

Brachylophus fasciatus

Species Authority

(Brongniart, 1800)

Common Name/s

Lau Banded Iguana

Species Status

Endangered

Organism Type

Reptile

Taxonomy

Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: Squamata
Family: Iguanidae

Environment/System

terrestrial

Invasive Species Threat Summary

The Lau banded iguana (Brachylophus fasciatus) is classed as Endangered according to the IUCN. Prior to genetic analysis all the banded iguanas were considered to belong to a single species however the Lau Banded Iguana is now recognised as distinct species from the Fiji Banded Iguana (Brachylophus bulabula) (Keogh et al. 2008, in Fisher, Grant & Harlow 2012). (Most previous references to iguanas in central Fiji are now attributed to B. bulabula). The Lau Banded Iguana is native only to the islands in the Lau Group of eastern Fiji and it has been introduced to Tonga (Fisher, Grant & Harlow 2012). Within the Lau Group, the iguana has been confirmed recently from only 11 islands ranging from Vanua Balavu in the north to Fulaga and Ogea in the south (R. Fisher pers. comm. 2011, in Fisher, Grant & Harlow 2012). Banded iguanas are abundant on only three islands – the two neighbouring Aiwa Islands and Vuaqava – all of which are uninhabited (Fisher, Grant & Harlow 2012). The Lau banded iguana occurs in a range of habitat types from volcanic islands with wet forest to raised limestone islands with dry forest (Fisher, Grant & Harlow 2012). They are sometimes found in marginal habitats of non-native plants, native hibiscus and degraded forest around villages and ocean margins (Fisher, Grant & Harlow 2012).

Threats faced by the Lau banded iguana vary from island to island but include deforestation, burning and fragmentation of native habitat and invasive predator/herbivore impacts. Lakeba (the biggest island in the Lau group) once supported large numbers of banded iguana but this subpopulation has now drastically declined due partly to the conversion of native forest to Caribbean pine (Pinus caribaea) plantation which is unsuitable habitat for iguana nesting and feeding (Fisher, Grant & Harlow 2012). On the islands where banded iguanas remain forest burning is widespread and it is predicted that these high deforestation rates will cause more local extinctions in the future (Fisher, Grant & Harlow 2012). Additional forms of habitat loss include logging and development of urban and village areas. In particular the harvesting of the Vesi tree (Intsia bijuga) has significantly reduced the native forest (Fisher, Grant & Harlow 2012). Proposed development of tourism resorts may threaten banded iguana populations and new infrastructure associated with cruise ships may be a source of novel invasive species unless biosecurity measures for boat traffic from Viti Levu are implemented.

In general black rats (Rattus rattus) and feral cats are the main mammalian predators which threaten iguanas. Of concern is the fact that Vuaqava (one of the three main islands where the Lau banded iguanas is abundant) has a large cat (Felis catus) population (Fisher, Grant & Harlow 2012). Mongooses have not been introduced to the Lau Group and maintaining the mongoose-free status of these islands is an important biosecurity issue.

Free-roaming domestic goats (Capra hircus) have recently been introduced to all three islands where the Lau banded iguana is abundant (Aiwa Islands and Vuaqava) (Fisher, Grant & Harlow 2012). These islands now lack a sufficient understory as goats presumably prevent seedling recruitment and regeneration of banded iguana habitat. Goats compete with iguana for food source plants introducing a competitive advantage promoting the spread of plant species unpalatable to both iguana and goats (Fisher, Grant & Harlow 2012). Goat rounding via fires further hastens the conversion of forest to grassland. Free-roaming domestic pigs (Sus scrofa) are also of concern as they can cause major disturbance in small forest patches turning forest floor to bare mud unsuitable as iguana habitat (Fisher, Grant & Harlow 2012).

Yellow crazy ants (Anoplolepis gracilipes) are invasive ecosystem modifiers which occur on many southern Lau islands and overlap in range with some areas where the Lau banded iguana may be present. Unknown triggers cause these ant populations to periodically increase in large numbers. These irruptions have been linked with reduced abundances of native skink and geckos (R. Fisher unpub. data, in Fisher, Grant & Harlow 2012). Yellow crazy ants may also negatively impact iguana populations however this remains unconfirmed and unstudied.

The deliberate or accidental movement of the American iguana (Iguana iguana) into the northern Lau Islands is a distinct possibility and it is therefore pertinent to talk about the work which has been done on the American Iguana in Fiji. This is due to the fact that the northern Lau Islands are close to Qamea where the Green Iguana was first introduced. Awareness campaigns (initiated by the American Iguana Eradication Task Force and the Critical Ecosystems Partnership Fund) were carried out in the region in 2010. An American Iguana Eradication Workshop was also held that year which covered biosecurity measures, inclusion of billboards at landing docks and formation of an iguana eradication team (CI 2013). An eradication strategy also formulated that year evaluated iguana capture methods and concluded that the best chance of success would be through implementing a community-based approach involving the removal of gravid and hatchling iguanas from nesting sites across three to five years (CI 2013). Telemetry studies and other research based on American iguana establishment, dispersal, habitat/food selection, population estimates and control was also conducted to remedy the paucity of information available for this invasive iguana. Further information on this research is available by referring to Status Report: The American iguana (Iguana iguana) in Fiji- May-August 2011.

Invasive Species Management Summary

There are no conservation measures in place for the Lau banded iguana and they are not known to occur in any protected areas (Fisher, Grant & Harlow 2012). All Brachylophus iguanas are protected from international trade by Appendix I of the Convention on International Trade in Endangered Species (CITES). Surveys of remaining populations and research on the impact of invasive predators and yellow crazy ants on iguana populations are needed. Further taxonomic genetic analysis is required to determine the range of this species. A Conservation Action Plan is greatly needed for this species. Confusion with Brachylophus bulabula and the assumption that they occur on many islands means that threats may be significantly under-represented for the Lau banded iguana.

References

 Refresh   |         
CountryLocationTypeInvasive SpeciesCommon NameImpact Mechanism
FijiAiwa LevuIslanddomestic goatGrazing/Herbivory/Browsing
FijiAiwa LevuIslandblack ratPredation (potential)
FijiAiwa LevuIslandYellow crazy antOther-physical disturbance (potential)
FijiAiwa LevuIslandsmall Asian mongoosePredation (potential)
FijiAiwa LevuIslandferal pigRooting/Digging (potential)
FijiAiwa LevuIslandcatPredation (potential)
FijiAiwa LevuIslandgreen iguanaCompetition (potential)

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An Initiative of the ACP Group, funded by the European Union under the 10th EDF