Year of compilation: 2012

Site description
Key biodiversity
Pressure/threats to key biodiversity
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 future sea level rise leading to inundation, and increased 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. Clipperton was inhabited between 1892 and 1917 introducing feral pigs. Feral pigs caused a sharp decline in the populations of masked and brown booby with only 150 and 500 respectively left in 1958 (Stager, 1964). Stager during his visit in 1958 shot all pigs present (58); this has lead to the rebuilding of the booby numbers (Pitman et al. 2005). During Pitman and others visit to Clipperton in 2000 Black rat was reported and evidence of impact on smaller breeding seabirds noted (such as Sooty Terns where only two eggs were found). Pitman and others (2005) predict the loss of smaller seabirds breeding on Clipperton due to predation in the future and a possible change to the structure of the larger bodied seabird colonies due to rat caused changes in vegetation. Polynesian Rat is ubiquitous throughout the Pacific (IUCN SSC Invasive Species Specialist Group 2012) and is assumed to be present. Polynesian Rat has been recorded predating adult seabirds as well as eggs and chicks (Kepler 1967). They have precipitated island extinctions in small-bodied, ground-nesting seabirds, but their impacts on larger or arboreal nesting seabirds appear to be lower (Atkinson 1985, Jones et al. 2008). Invasive Alien Species 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 known to be present and are having a limiting effect on seabirds, or causing population declines.

Conservation responses/actions for key biodiversity
Feral pigs were removed in 1958 during the visit by Stager. This led to the increase of breeding masked and brown boobies. No conservation action has taken place since. Black rats were recorded in 2000 and noted to be having a negative impact on smaller breeding seabirds and have the potential to alter vegetation cover impacting on larger seabird species.

Recommended citation
BirdLife International (2022) Important Bird Areas factsheet: Clipperton. Downloaded from on 02/07/2022.