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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
Common Shelduck Tadorna tadorna	LC	passage	2001-2006	14,480 individuals	A4i, B1i, C3
Common Shelduck Tadorna tadorna	LC	winter	2001-2006	3,064 individuals	B1i, C3
Common Teal Anas crecca	LC	passage	2001-2006	5,187 individuals	B1i, C3
Common Ringed Plover Charadrius hiaticula	LC	passage	2001-2006	690 individuals	B1i, C3
Eurasian Curlew Numenius arquata	NT	passage	2001-2006	2,180 individuals	B2
Eurasian Curlew Numenius arquata	NT	winter	2001-2006	1,535 individuals	B2
Black-tailed Godwit Limosa limosa	NT	passage	2001-2006	2,129 individuals	B1i, C3
Dunlin Calidris alpina	NT	passage	2001-2006	9,465 individuals	B2
Dunlin Calidris alpina	NT	winter	2001-2006	42,876 individuals	A4i, B1i, B2, C3
Common Redshank Tringa totanus	LC	winter	2001-2006	5,544 individuals	A4i, B1i, C3
Common Redshank Tringa totanus	LC	winter	2001-2006	4,359 individuals	A4i, B1i, C3
A4iii Species group - waterbirds	n/a	passage	2001-2006	45,896 individuals	A4iii, C4
A4iii Species group - waterbirds	n/a	winter	2001-2006	76,704 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
Common Shelduck Tadorna tadorna	5,300	3,064	individuals	58	unfavourable
Northern Pintail Anas acuta	3,210	162	individuals	6	very unfavourable
Anas crecca	8,830	8,830	individuals	100	favourable
Eurasian Golden Plover Pluvialis apricaria	2,650	1,560	individuals	59	unfavourable
Common Ringed Plover Charadrius hiaticula	205	690	individuals	100	favourable
Eurasian Curlew Numenius arquata	1,230	1,535	individuals	100	favourable
Eurasian Curlew Numenius arquata	1,340	2,180	individuals	100	favourable
Dunlin Calidris alpina	46,600	42,876	individuals	93	favourable
Dunlin Calidris alpina	7,800	9,465	individuals	100	favourable
Common Redshank Tringa totanus	4,350	5,544	individuals	100	favourable
Common Redshank Tringa totanus	4,610	4,359	individuals	95	favourable
A4iii Species group - waterbirds	35,198	458,976	individuals	100	favourable
A4iii Species group - waterbirds	102,890	76,704	individuals	75	near favourable

Pressure (threats to the trigger species and/or their habitats)
Threat	Timing	Scope	Severity	Result
No known threats	happening now	small area/few individuals (<10%)	no or imperceptible deterioration	low

Response (conservation actions taken for the trigger species and/or their habitats)
Protected areas	Management plan	Other action	Result
Whole area of site (>90%) covered by appropriate conservation designation	Unknown	Not assessed	low

Year	Protected Area	Designation	% overlap with IBA
1985	Mersey Estuary	Site of Special Scientific Interest (UK)	100
1995	Mersey Estuary	Ramsar Site, Wetland of International Importance	100
1995	Mersey Estuary	Nature Reserve	20
1996	Mersey Estuary	Special Protection Area (Birds Directive)	100
2000	New Ferry	Site of Special Scientific Interest (UK)	1
2011	Mersey Estuary	Marine Protected Area (OSPAR)	73

Habitat1	Habitat detail	% of IBA
Marine Intertidal		major (>10)
Marine Neritic		major (>10)
Marine Coastal/Supratidal		minor (<10)

1. IUCN Habitat classification.

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

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