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Location Spain, Galicia
Central coordinates 8o 57.00' West  42o 23.00' North
IBA criteria A4i, B1i, B3, C3
Area 467 ha
Altitude 0 - 119m
Year of IBA assessment 2000


Site description Two small islands in the Ría de Pontevedra estuary, covered by scrub and grasslands. The main human activity is tourism.

Key Biodiversity This is an important site for breeding seabirds.

Populations of IBA trigger species

Species Season Period Population estimate Quality of estimate IBA Criteria IUCN Category
European Shag Phalacrocorax aristotelis resident  1992  400-600 breeding pairs  medium  B3  Least Concern 
Larus michahellis resident  1992  2,000 breeding pairs  poor  A4i, B1i, C3  Not Recognised 

Protected areas

Protected area Designation Area (ha) Relationship with IBA Overlap with IBA (ha)  
Complexo Ons - O Grove - ES1140004 Habitats Directive 7,507 protected area overlaps with site 300  
Illa de Ons - ES0000254 Birds Directive 924 protected area contains site 467  


IUCN habitat Habitat detail Extent (% of site)
Shrubland Scrub  26%
Sea   -
Coastline Rock stacks and islets; Sea cliffs and rocky shores  26%

Land use

Land-use Extent (% of site)
fisheries/aquaculture -
not utilised 26%
tourism/recreation -

Protection status National None International None

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Recommended citation  BirdLife International (2015) Important Bird Areas factsheet: Ons islands. Downloaded from on 28/02/2015

To provide new information to update this factsheet or to correct any errors, please email BirdLife