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The site was identified as important in 2007 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 List1	Season	Year(s)	Size	IBA criteria
Gadwall Mareca strepera	LC	winter	2001-2006	357 individuals	B1i, C3
Pied Avocet Recurvirostra avosetta	LC	passage	2001-2006	649 individuals	B2
Pied Avocet Recurvirostra avosetta	LC	winter	2001-2006	628 individuals	B2, C6
Pied Avocet Recurvirostra avosetta	LC	breeding	1995	33 breeding pairs	C6
Common Ringed Plover Charadrius hiaticula	LC	passage	2001-2006	737 individuals	B1i, C3
Eurasian Curlew Numenius arquata	NT	passage	2001-2006	1,412 individuals	B2
Eurasian Curlew Numenius arquata	NT	winter	2001-2006	1,495 individuals	B2
Black-tailed Godwit Limosa limosa	NT	passage	2001-2006	3,299 individuals	B1i, C3
Black-tailed Godwit Limosa limosa	NT	winter	2001-2006	1,247 individuals	B1i, C3
Dunlin Calidris alpina	NT	passage	2001-2006	5,541 individuals	B2
Dunlin Calidris alpina	NT	winter	2001-2006	15,181 individuals	B1i, B2, C3
Common Redshank Tringa totanus	LC	winter	2001-2006	1,720 individuals	B1i, C3
A4iii Species group - waterbirds	n/a	passage	2001-2006	24,702 individuals	A4iii, C4
A4iii Species group - waterbirds	n/a	winter	2001-2006	47,805 individuals	A4iii, C4

1. The current IUCN Red List category. The category at the time of the IBA criteria assessment (2007) may differ.

Ideally the conservation status of the IBA will have been checked regularly since the site was first identified in 2007. The most recent assessment (2007) is shown below.

State (condition of the trigger species' populations)
Species	Reference	Actual	Units	% remaining	Result
Gadwall Mareca strepera	130	357	individuals	100	favourable
Pied Avocet Recurvirostra avosetta	205	628	individuals	100	favourable
Common Ringed Plover Charadrius hiaticula	585	737	individuals	100	favourable
Eurasian Curlew Numenius arquata	1,160	1,412	individuals	100	favourable
Eurasian Curlew Numenius arquata	1,110	1,495	individuals	100	favourable
Black-tailed Godwit Limosa limosa	255	1,247	individuals	100	favourable
Black-tailed Godwit Limosa limosa	515	3,299	individuals	100	favourable
Dunlin Calidris alpina	12,900	15,181	individuals	100	favourable
Dunlin Calidris alpina	5,650	5,541	individuals	99	favourable
Common Redshank Tringa totanus	1,680	1,285	individuals	77	not assessed
Common Redshank Tringa totanus	1,890	1,720	individuals	92	favourable
A4iii Species group - waterbirds	36,027	47,805	individuals	100	favourable

Pressure (threats to the trigger species and/or their habitats)
Threat	Timing	Scope	Severity	Result
Natural system modifications	likely in short term (within 4 years)	some of area/population (10-49%)	slow but significant deterioration	medium
Energy production and mining	likely in short term (within 4 years)	small area/few individuals (<10%)	moderate to rapid deterioration	low
Pollution	likely in short term (within 4 years)	small area/few individuals (<10%)	moderate to rapid deterioration	low
Transportation and service corridors	likely in short term (within 4 years)	small area/few individuals (<10%)	moderate to rapid deterioration	low
Residential and commercial development	likely in short term (within 4 years)	small area/few individuals (<10%)	moderate to rapid deterioration	low
Climate change and severe weather	happening now	small area/few individuals (<10%)	slow but significant deterioration	low

Response (conservation actions taken for the trigger species and/or their habitats)
Protected areas	Management plan	Other action	Result
Most of site (50-90%) covered (including the most critical parts for important bird species)	A management plan exists but it is out of date or not comprehensive	Some limited conservation initiatives are in place	low

Year	Protected Area	Designation	% overlap with IBA
1956	Northward Hill	Nature Reserve	1
1989	Inner Thames Marshes	Site of Special Scientific Interest (UK)	5
1991	South Thames Estuary and Marshes	Site of Special Scientific Interest (UK)	57
1991	Mucking Flats and Marshes	Site of Special Scientific Interest (UK)	3
1991	West Thurrock Lagoon & Marshes	Site of Special Scientific Interest (UK)	1
1994	Shorne Marshes	Nature Reserve	4
1998	Thames Estuary and Marshes	Special Protection Area (Birds Directive)	52
2000	Thames Estuary and Marshes	Ramsar Site, Wetland of International Importance	60
2000	Rainham Marshes	Nature Reserve	4
2001	Cliffe Pools	Nature Reserve	2
2003	Holehaven Creek	Site of Special Scientific Interest (UK)	2
2010	Rainham Marshes	Local Nature Reserve	1
2011	Thames Estuary and Marshes	Marine Protected Area (OSPAR)	27
2013	Medway Estuary	Marine Conservation Zone	2
2014	Medway Estuary	Marine Protected Area (OSPAR)	2

Habitat1	Habitat detail	% of IBA
Grassland	Humid grasslands	major (>10)
Marine Intertidal		major (>10)
Marine Neritic		major (>10)
Artificial/Terrestrial	Arable land	minor (<10)
Forest	Broadleaved deciduous woodland, Mixed woodland	minor (<10)
Marine Coastal/Supratidal		minor (<10)
Shrubland	Scrub	minor (<10)
Wetlands (inland)	Water fringe vegetation	minor (<10)

1. IUCN Habitat classification.

Land use	% of IBA
agriculture	-
nature conservation and research	-
urban/industrial/transport	-

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Recommended citation
BirdLife International (2024) Important Bird Area factsheet: Thames Estuary and Marshes (United Kingdom). Downloaded from https://datazone.birdlife.org/site/factsheet/thames-estuary-and-marshes-iba-united-kingdom on 23/11/2024.