Field guide: Ebb and Flow – The Swale Estuary, Kent

Kent’s Swale estuary is a nationally important site for wildfowl and waders. In winter, thousands of birds flock to this unique habitat in search of food exposed by the receding tide.

East Flood by Kath AustenTee 

Kent’s Swale estuary is a nationally important site for wildfowl and waders. In winter, thousands of birds flock to this unique habitat in search of food exposed by the receding tide.

The north Kent shoreline between Margate and the Isle of Grain features places that throng with wildlife – nowhere more so than the Swale estuary. This 13-mile channel separates the Isle of Sheppey from the mainland. ‘It’s all about the tides,’ says Geoff Ettridge of Medway Ramblers. ‘As the sea comes in and goes out, it creates a variety of changing habitats, from open sandbanks, where seals haul out, to vast mudflats, attracting flocks of birds in search of food.’ As well as leading group walks, Geoff is also a keen chronicler of his favourite walking routes. ‘The Swale is a long, narrow estuary with creeks and marshes on either side,’ he says. ‘But there are excellent routes to a number of locations, each with wide views over the estuary.’ He recommends heading for the village of Iwade, before Kingsferry Bridge, for a circular route via Chetney Marshes and Raspberry Hill. More remote still is Elmley National Nature reserve, on Sheppey itself, where a long path beside the tidal mudflats includes several bird hides. ‘The estuary is home to waders, such as curlews, oystercatchers and redshanks, which constantly probe the mud for molluscs, worms and crustaceans,’ says Geoff. ‘On the open water, you can see hundreds of pintail, wigeon, teal and other duck species.’ Another location Geoff recommends is Oare Marshes, on the edge of the Swale, near Faversham. It’s a reserve run by Kent Wildlife Trust and from the seawall path, which forms part of the Saxon Shore Way, you can gaze out over the estuary at overwintering dunlin and Brent geese. Merlins and short-eared owls also hunt over the saltmarsh fringe. As the meeting point of saltwater and freshwater, estuaries are unique habitats that act as nursery grounds for fish like skate, sole and bass. The mud is full of invertebrates and there are extensive mussel beds, which, together with the algae and eelgrass, provide a rich food source for birds. ‘Check out the tide tables and time your walk, as low tide means plenty of feeding birds,’ says Geoff. ‘And don’t forget your binoculars!’

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Drake Pintail photo by Jacob Spinks 

Picture: Jacob Spinks

Large numbers of these handsome ducks arrive each winter, swelling existing flocks on coastal estuaries. They are a little larger than a mallard, and the males have chocolate-coloured heads, white underparts, black-tipped wings and a distinctive pointed tail.

Curlew by thskyt 

Picture: thskyt

Europe’s largest wading bird, mottled dark brown and about the same size as a female pheasant, can be seen on estuary mudflats in winter, probing the ground with its long, downturned bill in search of worms and shellfish. Its long, bubbling call is unmistakable.

Native oyster credit H Zell 

Picture: H Zell

Native oyster
Native oyster populations are under threat. A bivalve mollusc, one shell is cupshaped and the other forms a flat lid. This is a good way to tell it apart from the invasive Pacific oyster, which was introduced to the UK in 1926 and has a much rougher, elongated shell.

Eelgrass bed 

This flowering marine plant is the staple food of Brent geese. Submerged or partly floating, the plant is rooted to the seabed and forms dense underwater meadows, providing nursery areas for young fish and stabilising the ground.

Common seal by Charles J Sharp 

Picture: Charles J Sharp 

Common seal
Grey or brown and with a rounded head, the common seal is often found inshore and around estuaries, where they feed on fish, crabs and mussels. They are agile swimmers, but out of the water they have a distinctive posture with the head and tail raised in a gentle curve. Common seals can live for up to 30 years.

Shelduck credit Jacob Spinks 

Picture: Jacob Spinks

With bold, colourful plumage, midway in size between a duck and goose, the shelduck is found all around the coast. It nests under dense bushes or in old rabbit burrows and lays a large number of eggs (up to 15), then after hatching the young are immediately led to the water to join others and form large creches.

Common mussel by Steven Severinghaus 

Picture: Steven Severinghaus

Common mussel
A familiar sight on estuary shores, tightly packed clusters of these black/blue bivalves (two shells that close together) can be found in large numbers, anchoring themselves to rocks by means of a thick fluid that hardens on contact with water. At low tide they are a popular source of food for the likes of oystercatchers and they are also harvested for the table.

Merlin credit anthony via Flickr 

Picture: Anthony via Flickr

Although usually associated with moors and uplands, Britain's smallest and quite elusive bird of prey tends to move to the coast in winter, where they hunt small birds which they take in flight. Despite their size, these are powerful falcons, often flying with very fast wing beats, interspersed with short glides when they close their wings.

Short eared owl credit Sindri Sklason 

Picture: Skindri Sklason

Short eared owl
A familiar sight around marshes and estuary edges, especially in winter, this medium sized owl can be seen hunting by day and feeds on small mammals. It flies with slow, rhythmic wing beats, gliding with outstretched wings low over the coastal fields. As befits its name, it has small ear-tufts which are only visible when it gets agitated or excited.