Hatu iti (28529)
French Polynesia, Oceania
Site overview
KBA status: confirmed
Year of last assessment: 2012
National site name: Hatu iti
Central coordinates: Latitude: -8.6800, Longitude: -140.6167
System: marine, terrestrial
Elevation (m): 0 to 232
Area of KBA (km2): 0.16303
KBA classification: Regional
Legacy site: Yes
Site details
Rationale for qualifying as KBA: This site qualifies as a Key Biodiversity Area of international significance that was identified using previously established criteria and thresholds for the identification of Important Bird and Biodiversity Areas (IBAs) and for which available data indicate that it does not meet global KBA criteria and thresholds set out in the Global Standard.
Threats
Summary of threats to biodiversity at KBA: Climate change is listed as the third greatest threat to seabirds globally (Croxall et al. 2012). It is predicted to decrease the land area of low-lying Pacific islands and cause complete inundation of some islands (IPCC 1997) leading to substantial population declines (Hatfield et al. 2012). Although no current data or predictions are available specific to this IBA climate change represents a potential threat to this site owing to the risk of frequency of storms. Invasive Alien Species represent the greatest threat to seabirds globally (Croxall et al. 2012), causing adult mortality and reduced productivity owing to egg and chick predation. Little data exists on the presence of invasive alien species at Hatu Iti. The atoll is uninhabited by humans, although it is visited by the Marshallese and evidence of a previous ship wreck was noted in 1964 (Amerson, 1967). Polynesian Rat does occur and there are unconfirmed reports of the introduction of another rat species in recent years. Polynesian Rat is ubiquitous throughout the Pacific (IUCN SSC Invasive Species Specialist Group 2012) and has been recorded predating adult seabirds as well as eggs and chicks (Kepler 1967). Black Rat, Feral Cat, Feral Pig and Feral Goat are all plausible but unconfirmed residents. Each can potentially cause declines in seabird colonies, and ungulates can exacerbate the threat from other invasive mammals through habitat modification (Atkinson 1985, Rodríguez et al. 2006, Jones et al. 2008, Duffy 2010). Overall, invasive mammals are suspected to be present and are likely to be having a limiting effect on seabirds, or causing population declines. Human disturbance and direct harvesting of seabirds are listed as threats to 26 and 23 of the 97 globally threatened seabirds respectively (Croxall et al. 2012). For Near Threatened and Least Concern species it is likely that human disturbance and consumption affect an even greater proportion, particularly of tropical species, for which major reductions in populations and/or breeding sites are increasingly indicated but seldom quantified, especially across the whole range of the many wide-ranging tropical seabird species (Croxall et al. 2012). Human disturbance and direct harvesting may occur at this site. The sustainability of such harvests is unknown but it may represent a threat to this population.
Additional information
References: Atkinson, I. A. E. (1985) The spread of commensal species of Rattus to oceanic islands and their effect on island avifaunas. Pages 35-81 in P. J. Moors, editor. Conservation of island birds. International Council for Bird Preservation, Cambridge, United Kingdom. Croxall, J. P., Butchart, S. H. M., Lascelles, B., Stattersfield, A. J., Sullivan, B., Symes, A. and Taylor, P. (2012) Seabird conservation status, threats and priority actions: a global assessment. Bird Conservation International 22: 1-34. Duffy, D. C. (2010) Changing Seabird Management in Hawai‘i: from exploitation through management to restoration. Waterbirds 33: 193-207. Hatfield, J. S., Reynolds, M. H., Seavy, N. E. and Krause, C. M. (2012) Population dynamics of Hawaiian seabird colonies vulnerable to sea-level rise. Conservation Biology 26: 667-678. IPCC – Intergovernmental Panel On Climate Change (1997) The Regional Impacts of Climate Change. An Assessment of Vulnerability. Geneva. IUCN SSC Invasive Species Specialist Group (2012) Rattus exulans. Global Invasive Species Database. Downloaded from http://www.issg.org/database/species/ecology.asp?si=170&fr=1&sts=sss on 8th October 2012. Jones, H. P., Tershy, B. R., Zavaleta, E. S., Croll, D. A., Keitt, B. S., Finkelstein, M. E. and Howald, G. R. (2008) Severity of the effects of invasive rats on seabirds: a global review. Conservation Biology 22: 16-26. Kepler, B. (1967) Polynesian rat predation on nesting Laysan Albatrosses and other Pacific seabirds. Auk 84: 426-430. Rodríguez, C., Torres, R. and Drummond, H. (2006) Eradicating introduced mammals from a forested tropical island. Biological Conservation 130: 98-105.