Mud, Mud, Glorious Mud! By RSPB’s Tony Whitehead

Poole Harbour is one of the best birdwatching estuaries in the UK, and currently featured on BBC Winterwatch. But what makes it such a special place, and why are there so many birds here in winter? The RSPB’s Tony Whitehead explains ...


"Mud, mud, glorious mud, there's nothing quite like it …".  So goes the well known Flanders and Swann song, and indeed whether or not you are a hippo, there certainly is nothing quite like the dark, slippy, oozy stuff. And there is nothing like the mud found on our estuaries.

Which may be surprising. Looking over acres of mudflats, the flat land between low and high tide, it would be easy to think this is just wasteland. Were it not of course for the animating grace of flocks of water birds, especially in winter. But the swirling flocks tell us that this is certainly no wasteland: there's something in this mud that is hugely attractive to hundreds of thousands of birds, from tiny dunlins to curlews, Europe's largest wading bird. And the attraction is that the mud is simply teeming with life, edible life, fuel for hungry feathered tummies.

Birds feeding on mud in estuary by Andy Hay (rspb-images.com)

Indeed, the calorific value of the estuary mud per square metre is said to be second only to rain forests. Calorific value? Yes, scientists have measured how many calories there are in different habitats, and estuary mud is the equivalent of a deep fried Mars bar.

Or at least, the life, the plants and animals in a square metre of mud is. A close look at the surface of estuary mud gives a clue to its aliveness. All those little piles of silt, like tiny mole hills, are signs of ragworms and lugworms. And all those squiggle lines on the surface are trails from small snails. Then there are the mussels and other shells. And that filamentous green stuff - eelgrass. Not to mention the small crabs. And shrimps. And so on. From a distance this is not obvious, but up close the mud is full of life.

Avocet on mud by Chris Gomersall (rspb-images.com)

It's this that the birds are feasting on, especially in the colder months when birds are frozen out of their breeding grounds up in the arctic and subarctic. And, wonderfully, each species of bird is adapted to exploit a slightly different food. Godwits have long bills for probing deep into the mud for worms. Turnstones are adept at turning stones. Dunlins have tiny bills for picking small creatures from near the surface. Oystercatchers have strong bills for prizing open or breaking mussels. Avocets have up-curved bills for sifting shrimps from the water. Each has been perfected over millions of years to make the most of different parts of the estuarine ecosystem, a beautifully balanced system that when it functions provides food for all.

Eleanor Bentall (rspb-images.com)

And each estuary, each patch of mud, is part of a global network of what are essentially fuelling stations for migratory birds. And it is the integrity of this system that needs our care and protection. To watch godwits on Poole Harbour in winter for instance, means that we need a chain of estuaries between the harbour and their breeding grounds up in Iceland. Without these stops they would not be able to get to Poole. This muddy global network has long had special recognition … back in the early 70s in Iran, conservationists from around the world signed the Ramsar Convention that set out to identify internationally important sites; work that continues today. Here in the South West places such as Poole Harbour, the Exe and Tamar Estuaries and the Severn are all identified as globally important.

Because of their importance, it is vital that these wonderful muddy places are given our special care. We need to make sure development does not adversely affect the mud and its wildlife. We need to make sure that birds can feed happily without undue disturbance. And we need to work out how to help make space for estuaries in the face of sea level rise.

Redshank feeding on mud by Andy Hay (rspb-images.com)

The RSPB is playing its part, and in many places we own and protect stretches of estuary … in fact in the south west many of our nature reserves are coastal. But we also need people to speak up for these muddy places too, to share with others that these are not wastelands, but incredibly important homes for hundreds of thousands of birds.

To keep up-to-date with all of the Winterwatch news at RSPB Arne, visit:
Facebook: facebook.com/RSPBEastDorset

Twitter: @RSPBArne

Website: rspb.org.uk/arne

 

To find out more about photographer Terry Bagley, click here.

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