4.20 BLACKWATER ESTUARY

LTC site code:CB Centre grid: TL9507 JNCC estuarine review site: 112 Habitat zonation: 2368 ha intertidal, 1587 ha subtidal, 766 ha nontidal Statutory status: Blackwater Estuary SPA (UK9009245), Dengie SPA (UK9009242), Blackwater Estuary Ramsar (7UK087), Dengie Ramsar (7UK073) Winter waterbird interest: Great Crested Grebe, Cormorant, Dark-bellied Brent Goose, Shelduck, Wigeon, Teal, Pintail, Shoveler, Goldeneye, Red-breasted Merganser, Oystercatcher, Avocet, Ringed Plover, Golden Plover, Grey Plover, Lapwing, Knot, Dunlin, Ruff, Black-tailed Godwit, Bar-tailed Godwit, Curlew, Redshank, Waterbird assemblage

SITE DESCRIPTION fisheries and jet-skiing. The site is not heavily urbanised. The River Blackwater opens out at on the coast to form one of the largest and most COVERAGE AND INTERPRETATION important estuaries in East Anglia. The site is adjacent to the to the north and The Blackwater Estuary was covered by the Dengie Flats to the south. Additionally, Abberton scheme during the winter of 1994–95, with counts Reservoir lies only a few miles to the north. There being carried out during all four months. Figure is a wide diversity of habitats, with a large area of 4.20.1 shows the positions of the 46 sections mudflats but also saltmarsh, creeks, channels counted for the survey. and islands. Deposition of shingle and shell banks and exposed gravel beds are features of the tidal The majority of the LTC site is covered by SPA flats. Behind the sea-walls, important areas of designation, mostly by the Blackwater Estuary coastal grassland occur. Much of the Blackwater SPA (which also extends a little further east on saltmarsh is suffering erosion although in a the north shore into the area covered by the Colne number of locations managed realignment of the LTCs) but also by some of the Dengie SPA in the sea-defences is taking place which will create new south-east (Figure 4.20.2). The Blackwater Estuary estuarine habitat. Many of the human activities SPA also covers additional nontidal areas around on the estuary are leisure-related, especially the estuary, notably at Old Hall Marshes (initially boating, but also beach recreation, wildfowling, designated as a separate SPA but later subsumed)

Figure 4.20.1: LTC sections at the Blackwater Estuary, winter 1994–95

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Figure 4.20.2: LTC and SPA boundaries, with overlap, at the Blackwater Estuary and Wick Marshes. Any discussion of the counts, these being found mostly on adjacent the birds of the sites and/or SPAs around this nontidal habitats such as at Old Hall and part of the Essex coast should be careful to take Marshes. these boundary differences into account. In the future, the subdivision of the coast into separate The totals maps show that almost all of the site sites should take the SPA boundaries into was used by large numbers of birds, although key consideration. The boundaries of the Ramsar sites areas appear to be the central parts of the north are entirely coincident with those of the SPAs. shore and the channels either side of Old Hall Marshes. Most of the key species were similarly Clearly, there is great scope for daily movements widespread, such as Brent Goose, Shelduck, of birds between sites. For example, many of the Oystercatcher, Ringed Plover, Lapwing, Dunlin, Knot feeding in the south-east of the Blackwater Curlew and Redshank. Wigeon, Teal and Pintail appear to be roosting at Dengie (D. Wood pers. were more localised, with Old Hall Marshes clearly comm.). Similar movements of birds between the important for the first two as well as supporting Blackwater and Colne are also likely. As well as the highest concentrations of Goldeneyes and movements between the estuary and the imme- Red-breasted Mergansers. Golden Plovers were diately adjacent nontidal habitats, such as Old distributed widely but locally around the site. Grey Hall Marshes, the important site of Abberton Plovers showed a clear preference for the central Reservoir is situated only a few miles north of north shore, along with Bar-tailed Godwits. Black- the estuary and it seems certain that birds, tailed Godwits occurred in higher densities in the especially wildfowl, move between the two sites. inner parts of the estuary. Knot were mostly found between St Lawrence Bay and WATERBIRD DISTRIBUTION but with some on the inner estuary. Great Crested Grebes were present in small numbers with Low tide distribution maps from the winter of Cormorants more widespread. Ruff were only 1994–95 are presented for 21 of the 23 species of noted at Salcott Channel. principal interest listed above. For clarity, smaller dots are used to display the distributions of Golden Plover, Lapwing and Dunlin. Additional maps of total birds and total birds weighted by 1% threshold value are also presented (Figure 4.20.3). Of the remaining species, very few Shovelers and no Avocets were recorded during

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TOTAL (1 DOT = 5 BIRDS) WEIGHTED

GREAT CRESTED GREBE CORMORANT

DARK-BELLIED BRENT GOOSE SHELDUCK

WIGEON TEAL

Figure 4.20.3 (i): Low tide waterbird distributions recorded at the Blackwater Estuary, winter 1994-95

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PINTAIL GOLDENEYE

RED-BREASTED MERGANSER OYSTERCATCHER

RINGED PLOVER GOLDEN PLOVER

GREY PLOVER LAPWING

Figure 4.20.3 (ii): Low tide waterbird distributions recorded at the Blackwater Estuary, winter 1994-95

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KNOT DUNLIN

RUFF BLACK-TAILED GODWIT

BAR-TAILED GODWIT CURLEW

REDSHANK

Figure 4.20.3 (iii): Low tide waterbird distributions recorded at the Blackwater Estuary, winter 1994-95

E S T U A R I N E W A T E R B I R D S A T L O W T I D E 97 4.21 DENGIE FLATS LTC site code:CD Centre grid: TM0504 JNCC estuarine review site: 113 Habitat zonation: 2369 ha intertidal, 713 ha subtidal, 497 ha nontidal Statutory status: Dengie SPA (UK9009242), Dengie Ramsar (7UK073) Winter waterbird interest: Red-throated Diver, Great Crested Grebe, Cormorant, Dark-bellied Brent Goose, Oystercatcher, Grey Plover, Lapwing, Knot, Dunlin, Black-tailed Godwit, Bar-tailed Godwit, Waterbird assemblage

SITE DESCRIPTION covered by the LTCs is within the Dengie SPA boundary. The SPA extends a little way north- Dengie Flats form a continuous mudflat on the wards and southwards, taking in parts of the Essex coast between the mouths of the Blackwa- Blackwater Estuary and Crouch–Roach Estuary ter and Crouch–Roach Estuaries. There are LTC sites respectively. Future LTCs in this area extensive growths of Enteromorpha algae on the should endeavour to match up more closely the flats, which themselves grade into saltmarsh, SPA and LTC boundaries. The boundaries of the relatively unusual in an open-coast situation. Ramsar site are entirely coincident with those of Most of the grazing marshes, which are now the SPA. behind the sea-wall, have been claimed for agriculture. The site is relatively remote but some Obviously, given the proximity of the Blackwater human activities do occur, including watersports, and Crouch–Roach Estuaries, a certain amount beach recreation, bait-digging and wildfowling. of movement between sites occurs. Notably, Knot feeding on the south-east part of the Blackwater COVERAGE AND INTERPRETATION Estuary make use of roost sites in the Dengie area. Additionally, a number of species feeding at Dengie Flats was covered by the scheme during the southern end of Dengie also make use of the 1992–93 winter, although no February count Maplin Sands to the south of the Crouch for was made. Figure 4.21.1 shows the positions of feeding, and some roost on Foulness (J. Alderton, the 12 sections counted for the survey. D. Wood pers. comm.). Similarly, some species Figure 4.21.2 shows that the whole of the area (such as Lapwing) may utilise the non-estuarine hinterland.

Figure 4.21.1: LTC sections at Dengie Flats, winter 1992–93

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Figure 4.21.2: LTC and SPA boundaries, with overlap, at Dengie Flats

WATERBIRD DISTRIBUTION Generally, the totals maps show relatively even distributions of birds across the site, with the Low tide distribution maps from the winter of higher density on the southernmost section 1992–93 are presented for eight of the 11 species presumably a result of the smaller shore width of principal interest listed above. For clarity, here. Most species of note occurred widely, with smaller dots are used to display the distributions the maps showing slightly different preferences of Knot and Dunlin. Additional maps of total birds by different species. Perhaps most noteworthy and total birds weighted by 1% threshold value was the separation of the two species of godwit are also presented (Figure 4.21.3). Of the remaining into distinct areas with a relatively small degree species, no Red-throated Divers and only small of overlap between the two. numbers of Great Crested Grebes and Cormorants were noted, presumably due to the difficulties of viewing offshore species at the longer distances occurring at low tide.

DARK-BELLIED TOTAL (1 DOT = 5 BIRDS) WEIGHTED BRENT GOOSE

Figure 4.21.3 (i): Low tide waterbird distributions recorded at Dengie Flats, winter 1992-93

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OYSTERCATCHER GREY PLOVER LAPWING

KNOT DUNLIN BLACK-TAILED GODWIT

BAR-TAILED GODWIT Figure 4.21.3 (ii): Low tide waterbird distributions recorded at Dengie Flats, winter 1992-93

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LTC site code:DR Centre grid: TQ9694 JNCC estuarine review site: 114 Habitat zonation: 749 ha intertidal, 962 ha subtidal, 534 ha nontidal Statutory status: Crouch and Roach Estuaries SPA (UK9009244), Foulness SPA (UK9009246), Dengie SPA (UK9009242), Crouch and Roach Estuaries Ramsar (7UK085), Foulness Ramsar (7UK102), Dengie Ramsar (7UK073) Winter waterbird interest: Little Grebe, Great Crested Grebe, Cormorant, Dark-bellied Brent Goose, Shelduck, Wigeon, Oystercatcher, Avocet, Golden Plover, Grey Plover, Lapwing, Knot, Dunlin, Black-tailed Godwit, Bar-tailed Godwit, Curlew, Redshank, Waterbird assemblage.

SITE DESCRIPTION COVERAGE AND INTERPRETATION

The Crouch Estuary and its southern tributary, The Crouch–Roach Estuary was counted at low the Roach, are both long, narrow, muddy estuaries tide during 1995–96 with counts made in all four which reach the Essex coast at the northern end months. Figure 4.22.1 shows the positions of the of Foulness Island. The estuaries are largely 42 sections counted for the survey. flanked by farmland, much of it claimed from es- tuarine habitat, although there are some areas Figure 4.22.2 shows that almost the whole area of saltmarsh also, especially at Bridgemarsh covered by the counts is designated as SPA, mostly Island, Brandy Hole Creek and Stow Creek. The within the Crouch and Roach Estuaries SPA, but nature of the site means that the area of intertidal five of the count sections overlap with the substrate is relatively small in comparison to the Foulness SPA. Additionally, there is overlap of apparent size of the estuary. The southern parts the site with the Dengie SPA but to a much lesser of the Roach Estuary develop into a tangle of degree, involving half of the outermost section creeks, some of which extend through to Maplin on the north shore of the Crouch. The boundaries Sands. The site has little urbanisation or of the Ramsar sites are entirely coincident with industry, but it is widely used for watersports. those of the SPAs. Wildfowling occurs over most of the estuary.

Figure 4.22.1: LTC sections at the Crouch–Roach Estuary, winter 1995–96

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Figure 4.22.2: LTC and SPA boundaries, with overlap, at the Crouch–Roach Estuary

An assessment of waterbird use of the Crouch– Overall, bird density was clearly higher on the Roach and adjoining sites must take into account inner parts of each river. Few species were found the likely frequent movement of birds between at high density at the mouth, although sites. At the mouth of the Crouch–Roach, daily concentrations of Brent Geese and Golden Plovers movement is likely to and from both Dengie Sands were found around the confluence of the two and Maplin Sands, whereas along the southern ‘arms’ of the estuary. The Roach Estuary was edge of the site, movement will be frequent generally less densely occupied than the Crouch, between here and the Foulness complex of creeks but the Roach did support higher concentrations and marshes. of Redshanks and Curlews, plus the majority of the Black-tailed Godwits at the site. Shelducks, WATERBIRD DISTRIBUTION Brent Geese, Lapwings and Dunlin were also common along the Roach. The Crouch, especially Low tide distribution maps from the winter of the inner parts around Bridgemarsh Island and 1995–96 are presented for 13 of the 17 species of Brandy Hole Creek, was the key area at low tide principal interest listed above. For clarity, smaller for Wigeon, Lapwings and Little Grebes and also dots are used to display the distributions of Brent held high concentrations of Brent Geese, Goose, Wigeon and Dunlin. Additional maps of Shelducks, Golden Plovers and Dunlin. total birds and total birds weighted by 1% Cormorants, Oystercatchers and Grey Plovers threshold value are also presented (Figure 4.22.3). were widespread in small numbers. Of the remaining species, only small numbers of Great Crested Grebes, Avocets and Bar-tailed Godwits were noted and Knot were not recorded. These species would not be expected in large numbers on the Crouch–Roach Estuary itself, and their inclusion (and that of many of the other species present) on the list of interest species above is due to the small degree of overlap with the Dengie SPA and Foulness SPA.

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TOTAL WEIGHTED

LITTLE GREBE CORMORANT

DARK-BELLIED BRENT GOOSE SHELDUCK

WIGEON OYSTERCATCHER

Figure 4.22.3 (i) Low tide waterbird distributions recorded at the Crouch-Roach Estuary, winter 1995-96

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GOLDEN PLOVER GREY PLOVER

LAPWING DUNLIN

BLACK-TAILED GODWIT CURLEW

REDSHANK

Figure 4.22.3 (ii) Low tide waterbird distributions recorded at the Crouch-Roach Estuary, winter 1995-96

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