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The site was identified as internationally important for bird conservation in 2014 because it was regularly supporting significant populations of the species listed below, meeting ('triggering') IBA criteria.

Populations meeting IBA criteria ('trigger species') at the site:

Species	Red List	Season (year/s of estimate)	Size	IBA criteria
Pycroft's Petrel Pterodroma pycrofti	VU	breeding (1998)	1,483–6,995 pairs	A1, A4ii
Grey-faced Petrel Pterodroma gouldi	LC	breeding (1961–2013)	15,636–45,592 pairs	A4ii
Flesh-footed Shearwater Ardenna carneipes	NT	breeding (1966–2013)	2,872–12,073 pairs	A4ii
Little Shearwater Puffinus assimilis	LC	breeding (1934–2013)	2,685–15,743 pairs	A4ii
Common Diving-petrel Pelecanoides urinatrix	LC	breeding (1961–2013)	61,344–524,493 pairs	A4ii
New Zealand Kaka Nestor meridionalis	VU	resident (-)	present	A1
A4iii Species group - seabirds	n/a	breeding (1990–1999)	100,000-499,999 pairs	A4iii

Ideally the conservation status of the IBA will have been checked regularly since the site was first identified in 2014. The most recent assessment (2014) is shown below.

Pressure (threats to the trigger species and/or their habitats)
Threat	Timing	Scope	Severity	Result
Invasive and other problematic species and genes	likely in long term (>4 years)	some of popul­ation/area (10–49%)	moderate decline (10–30% over 3 gener­ations)	medium
Pollution	happe­ning now	few indivi­duals/small area (<10%)	no or slight decline (<1% over 3 gener­ations)	low
Human intrusions and disturbance	likely in short term (<4 years)	few indivi­duals/small area (<10%)	no or slight decline (<1% over 3 gener­ations)	low

Response (conservation actions taken for the trigger species and/or their habitats)
Designation	Planning	Action	Result
Not assessed	Not assessed	Not assessed	not assessed

Year	Protected Area	Designation (management category)	% coverage of IBA
1963	Kawhitu Island (Stanley)	Nature Reserve (Ia)	25
1963	Double Island (Moturehu)	Nature Reserve (Ia)	8
1971	Korapuki Island	Scenic Reserve (III)	5
1971	Atiu or Middle Island	Scenic Reserve (III)	4
1971	Green Island	Scenic Reserve (III)	1
1972	Red Mercury Island (Whakau)	Scenic Reserve (III)	58
1993	Mercury Island Group	Wildlife Sanctuary (IV)	55

Habitat	% of IBA	Habitat detail
Forest	major (>10)
Marine Coastal/Supratidal	major (>10)
Marine Intertidal	major (>10)
Shrubland	major (>10)
Grassland	minor (<10)

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Recommended citation
BirdLife International (2024) Important Bird Area factsheet: Mercury Islands (New Zealand). Downloaded from https://datazone.birdlife.org/site/factsheet/mercury-islands-iba-new-zealand on 26/12/2024.