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Location United Kingdom, North
Central coordinates 3o 16.16' West  54o 10.39' North
IBA criteria A4iii, B1i, B2, C3, C4, C6
Area 6,756 ha
Altitude 0 - 15m
Year of IBA assessment 2007

Royal Society for the Protection of Birds

Site description The IBA is situated to the north-west of Morecambe Bay, and covers a complex of habitats including intertidal mudflats, saltmarshes, sand-dunes and lagoons. The former iron-ore workings at Hodbarrow now comprise a lagoon of considerable wildlife interest. The estuary is important for breeding terns, wintering and passage wildfowl and waders.

Populations of IBA trigger species

Species Season Period Population estimate Quality of estimate IBA Criteria IUCN Category
Northern Pintail Anas acuta winter  2001-2006  1,550 individuals  good  B1i, C3  Least Concern 
Common Redshank Tringa totanus passage  2001-2006  1,630 individuals  good  B1i, C3  Least Concern 
Common Redshank Tringa totanus winter  2001-2006  1,720 individuals  good  B1i, C3  Least Concern 
Eurasian Curlew Numenius arquata winter  2001-2006  2,190 individuals  good  B2  Near Threatened 
Dunlin Calidris alpina winter  2001-2006  10,600 individuals  good  B2  Least Concern 
Sandwich Tern Thalasseus sandvicensis breeding  2000  340 breeding pairs  good  B2, C6  Least Concern 
Sandwich Tern Thalasseus sandvicensis breeding  2006  300 breeding pairs  poor  B2, C6  Least Concern 
Little Tern Sternula albifrons breeding  2000  26 breeding pairs  good  C6  Least Concern 
A4iii Species group - waterbirds winter  2001-2006  30,054 individuals  good  A4iii, C4   

IBA Monitoring

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

Natural system modifications other ecosystem modifications happening now small area/few individuals (<10%) slow but significant deterioration low

Anas acuta Northern Pintail 1550 1000 individuals 65 unfavourable
Charadrius hiaticula Common Ringed Plover 585 290 individuals 50 unfavourable
Tringa totanus Common Redshank 1630 1732 individuals 100 favourable
Tringa totanus Common Redshank 1630 1732 individuals 100 favourable
Tringa totanus Common Redshank 1720 2262 individuals 100 favourable
Limosa lapponica Bar-tailed Godwit 315 83 individuals 27 very unfavourable
Numenius arquata Eurasian Curlew 2190 2044 individuals 94 favourable
Calidris canutus Red Knot 3580 212 individuals 6 very unfavourable
Calidris canutus Red Knot 5300 1235 individuals 24 very unfavourable
Calidris alpina Dunlin 10600 6244 individuals 59 unfavourable
Thalasseus sandvicensis Sandwich Tern 340 300 breeding pairs 89 near favourable
Sternula albifrons Little Tern 26 16 breeding pairs 62 unfavourable
Species group - waterbirds A4iii 36093 30054 individuals 84 near favourable
Species group - waterbirds A4iii 21902 18312 individuals 84 near favourable

Whole area of site (>90%) covered by appropriate conservation designation  A management plan exists but it is out of date or not comprehensive  Not assessed  low 

Protected areas

Protected area Designation Area (ha) Relationship with IBA Overlap with IBA (ha)  
Duddon Estuary Site of Special Scientific Interest 6,786 is identical to site 6,756  
Duddon Estuary Wetlands of International Importance (Ramsar) 6,806 is identical to site 6,756  


IUCN habitat Habitat detail Extent (% of site)
Forest Broadleaved deciduous woodland  1%
Shrubland Scrub  1%
Grassland   2%
Wetlands (inland) Mud flats and sand flats; Rivers and streams; Salt marshes; Sand dunes and beaches; Shingle or stony beaches; Standing freshwater  96%

Land use

Land-use Extent (% of site)
tourism/recreation -

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Recommended citation  BirdLife International (2016) Important Bird and Biodiversity Area factsheet: Duddon Estuary. Downloaded from on 28/10/2016

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