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Location United Kingdom, South East
Central coordinates 0o 39.86' East  51o 23.98' North
IBA criteria A4iii, B1i, B2, C2, C3, C4, C6
Area 4,668 ha
Altitude 0 - 15m
Year of IBA assessment 2007

Royal Society for the Protection of Birds

Site description The Medway estuary forms a single tidal system with the Swale and joins the Thames estuary between the Isle of Grain and Sheerness. It has a complex arrangement of tidal channels, which drain around large islands of saltmarsh and grazing-marsh. The mudflats support extensive beds of algae and eel-grass Zostera. The IBA is important for wintering and passage wildfowl. Terns and gulls breed on saltmarsh islands, and wildfowl breed on the grazing-marshes.

Populations of IBA trigger species

Species Season Period Population estimate Quality of estimate IBA Criteria IUCN Category
Northern Pintail Anas acuta winter  2001-2006  1,118 individuals  good  B1i, C3  Least Concern 
Pied Avocet Recurvirostra avosetta passage  2001-2006  576 individuals  good  B2, C6  Least Concern 
Pied Avocet Recurvirostra avosetta winter  2001-2006  860 individuals  good  B1i, B2, C2, C6  Least Concern 
Pied Avocet Recurvirostra avosetta breeding  2002  138 breeding pairs  good  C6  Least Concern 
Common Redshank Tringa totanus winter  2001-2006  1,537 individuals  good  B1i, C3  Least Concern 
Eurasian Curlew Numenius arquata winter  2001-2006  1,298 individuals  good  B2  Near Threatened 
Dunlin Calidris alpina winter  2001-2006  7,024 individuals  good  B2  Least Concern 
Sandwich Tern Thalasseus sandvicensis breeding  2006  504 breeding pairs  good  B1i, B2  Least Concern 
A4iii Species group - waterbirds winter  2001-2006  25,547 individuals  good  A4iii, C4   

Protected areas

Protected area Designation Area (ha) Relationship with IBA Overlap with IBA (ha)  
Medway Estuary and Marshes Birds Directive 4,684 is identical to site 4,668  
Medway Estuary and Marshes Site of Special Scientific Interest 4,749 is identical to site 4,668  
Medway Estuary and Marshes Wetlands of International Importance (Ramsar) 4,697 is identical to site 4,668  


IUCN habitat Habitat detail Extent (% of site)
Grassland Humid grasslands  -
Wetlands (inland) Mud flats and sand flats; Rivers and streams; Salt marshes; Shingle or stony beaches; Tidal rivers and enclosed tidal waters; Water fringe vegetation  -
Artificial - terrestrial Arable land  -

Land use

Land-use Extent (% of site)
agriculture -
fisheries/aquaculture -
tourism/recreation -
urban/industrial/transport -

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Recommended citation  BirdLife International (2014) Important Bird Areas factsheet: Medway Estuary and Marshes. Downloaded from on 21/09/2014

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