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Location United Kingdom, North West
Central coordinates 2o 49.81' West  53o 17.99' North
IBA criteria A4i, A4iii, B1i, B2, C3, C4
Area 5,007 ha
Altitude 0 - 12m
Year of IBA assessment 2007

Royal Society for the Protection of Birds



Site description Extensive intertidal areas in the Mersey estuary, including large areas of mudflats and saltmarshes. The estuary is of international importance for wintering wildfowl and waders.

Populations of IBA trigger species

Species Season Period Population estimate Quality of estimate IBA Criteria IUCN Category
Common Shelduck Tadorna tadorna passage  2001-2006  14,480 individuals  good  A4i, B1i, C3  Least Concern 
Common Shelduck Tadorna tadorna winter  2001-2006  3,064 individuals  good  B1i, C3  Least Concern 
Common Teal Anas crecca passage  2001-2006  5,187 individuals  good  B1i, C3  Least Concern 
Common Ringed Plover Charadrius hiaticula passage  2001-2006  690 individuals  good  B1i, C3  Least Concern 
Common Redshank Tringa totanus winter  2001-2006  5,544 individuals  good  A4i, B1i, C3  Least Concern 
Common Redshank Tringa totanus winter  2001-2006  4,359 individuals  good  A4i, B1i, C3  Least Concern 
Black-tailed Godwit Limosa limosa passage  2001-2006  2,129 individuals  good  B1i, C3  Near Threatened 
Eurasian Curlew Numenius arquata passage  2001-2006  2,180 individuals  good  B2  Near Threatened 
Eurasian Curlew Numenius arquata winter  2001-2006  1,535 individuals  good  B2  Near Threatened 
Dunlin Calidris alpina passage  2001-2006  9,465 individuals  good  B2  Least Concern 
Dunlin Calidris alpina winter  2001-2006  42,876 individuals  good  A4i, B1i, B2, C3  Least Concern 
A4iii Species group - waterbirds passage  2001-2006  45,896 individuals  good  A4iii, C4   
A4iii Species group - waterbirds winter  2001-2006  76,704 individuals  good  A4iii, C4   

IBA Monitoring

2007 low very unfavourable low
Population
Good - based on reliable and complete / representative data

No known threats no known threats happening now small area/few individuals (<10%) no or imperceptible deterioration low

Anas acuta Northern Pintail 3210 162 individuals 6 very unfavourable
Tadorna tadorna Common Shelduck 5300 3064 individuals 58 unfavourable
Anas crecca Common Teal 8830 8830 individuals 100 favourable
Pluvialis apricaria Eurasian Golden Plover 2650 1560 individuals 59 unfavourable
Charadrius hiaticula Common Ringed Plover 205 690 individuals 100 favourable
Tringa totanus Common Redshank 4610 4359 individuals 95 favourable
Tringa totanus Common Redshank 4350 5544 individuals 100 favourable
Numenius arquata Eurasian Curlew 1230 1535 individuals 100 favourable
Numenius arquata Eurasian Curlew 1340 2180 individuals 100 favourable
Calidris alpina Dunlin 46600 42876 individuals 93 favourable
Calidris alpina Dunlin 7800 9465 individuals 100 favourable
Species group - waterbirds A4iii 35198 458976 individuals 100 favourable
Species group - waterbirds A4iii 102890 76704 individuals 75 near favourable

Whole area of site (>90%) covered by appropriate conservation designation  Unknown  Not assessed  low 

Protected areas

Protected area Designation Area (ha) Relationship with IBA Overlap with IBA (ha)  
Mersey Estuary Birds Directive 4,498 is identical to site 4,498  
Mersey Estuary Site of Special Scientific Interest 6,715 protected area contains site 5,007  
Mersey Estuary Wetlands of International Importance (Ramsar) 5,033 is identical to site 5,007  

Habitats

IUCN habitat Habitat detail Extent (% of site)
Wetlands (inland) Mud flats and sand flats; Rivers and streams; Salt marshes; Standing freshwater; Tidal rivers and enclosed tidal waters; Water fringe vegetation  -
Coastline Sea cliffs and rocky shores  -

Land use

Land-use Extent (% of site)
nature conservation and research -
urban/industrial/transport -

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Recommended citation  BirdLife International (2014) Important Bird Areas factsheet: Mersey Estuary. Downloaded from http://www.birdlife.org on 28/12/2014

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