Yva Momatiuk & John Eastcott / Bald Eagle (Haliaeetus leucocephalus) adult on mud-flats at low-tide, spring, south central Alaska

LYNN M. STONE / American Oystercatcher (Haematopus palliatus) foraging on tidal mud flats with bivalve in beak. Pinellas County, Florida, USA, March.

Terry Whittaker / 2020VISION / Bait digging on mud flats, with wind turbines in background, South Swale, Kent, England, UK, December

Terry Whittaker / 2020VISION / Three men walking out to go bait digging on mud flats, South Swale, Kent, England, UK, November.

Gerrit Vyn / Juvenile Sharp tailed sandpiper (Calidris acuminata) foraging on mud flats, Yukon Delta National Wildlfie Refuge, Alaska, USA, September

Ernie Janes / Fishing boat grounded on mud flats at low tide, Brancaster, North Norfolk, UK, winter

Philippe Clement / Man with clamming rake and bucket, digging for clams on tidal mud flats. Bay of the Somme, Picardy, France, March 2011.

Philippe Clement / Man equipped with clamming rake and bucket, digging for clams on tidal mud flats. Bay of the Somme, Picardy, France, March 2011.

Terry Whittaker / 2020VISION / Flock of Avocet (Recurvirostra avosetta) feeding on mud flats at low tide with Coryton Oil refinery in background, Site of new DP World London Gateway container port, River Thames, Essex, UK, April 20...

Andy Sands / Curlew (Numenius arquata) probing for food on mud flats at low tide. Norfolk, UK, October.

Andy Sands / Black Tailed Godwit (Limosa limosa) walking on mud flats at low tide. Norfolk, UK, October.

Andy Sands / Curlew (Numenius arquata) on mud flats at low tide. Norfolk, UK, October.

Andy Sands / Bar-tailed Godwit (Limosa lapponica) on mud flats at low tide. Norfolk, UK, December.

Andy Sands / Redshank (Tringa totanus) walking on mud flats at low tide. Norfolk, UK, October.

Andy Sands / Redshank (Tringa totanus) on mud flats at low tide. Norfolk, UK, October.

Andy Sands / Dunlin (Calidris alpina) on mud flats at low tide. Norfolk, UK, October.

Andy Sands / Redshank (Tringa totanus) walking on mud flats at low tide. Norfolk, UK, October.

Andy Sands / Curlew (Numenius arquata) on mud flats at low tide. Norfolk, UK, October.

Andy Sands / Dunlin (Calidris alpina) on mud flats at low tide. Norfolk, UK, October.

Andy Sands / Curlew (Numenius arquata) on mud flats at low tide. Norfolk, UK, October.

Andy Sands / Curlew (Numenius arquata) on mud flats at low tide. Norfolk, UK, October.

John Waters / Old wooden hull of ship or barge sunk into the sands at Berrow Flats, Bristol Channel, Somerset, UK. October 2010

John Waters / Old wooden hull of ship or barge sunk into the sands at Berrow Flats, Bristol Channel, Somerset, UK. October 2010

John Waters / Sunset at Berrow Flats close to Brean Down, looking towards Bristol Channel at low tide. Somerset, UK. October 2010.

David Woodfall / View of the Severn estuary at low tide, with mud flats exposed. This habitat is potentially threatened by proposed barrage, Gloucestershire, England, UK April 2010

Tim Laman / Mudskippers {Periophthalmus sp} climbing into the shell of a mangrove crab on the mud flats at low tide, Sundarbans, Khulna Province, Bangladesh.

Kevin Schafer / Dry mud flats, Death Valley National Park, California

Hanne & Jens Eriksen / Kentish plover {Charadrius alexandrinus} on mud flats, Socotra, Yemen

Hanne & Jens Eriksen / Great egret {Ardea alba} (right) and Western reef herons {Egretta gularis} on mud flats, Barr Al Hikman, Oman

Ingo Arndt / Grizzly Bear (Ursus arctos horribilis) tracks on tidal flats, Alaska

Ingo Arndt / Grizzly Bear (Ursus arctos horribilis) tracks on tidal flats, Alaska

Ingo Arndt / Grizzly Bear (Ursus arctos horribilis) digging for clams on tidal flats, Alaska

Ingo Arndt / Grizzly Bear (Ursus arctos horribilis) cub on tidal flats, Alaska

Ingo Arndt / Grizzly Bear (Ursus arctos horribilis) digging for clams on tidal flats, Alaska

Ingo Arndt / Grizzly Bear (Ursus arctos horribilis) digging for clams on tidal flats, Alaska

Winfried Wisniewski / White Ibis (Eudocimus albus) walking on mud flats, Florida

Juergen Freund / Aerial of Mud flats and mangroves of Derby, in the Kimberley, Western Australia

Juergen Freund / Aerial of Mud flats and mangroves, and Derby Jetty. Derby, Kimberley, Western Australia

Juergen Freund / Aerial of Mud flats and mangroves of Derby, King Sound, Western Australia

Juergen Freund / Aerial of mud flats and mangroves of Derby, in the Kimberley, Western Australia

Juergen Freund / Aerial Mud flats and mangroves of Derby, in the Kimberley, Western Australia

Pete Oxford / Dry cracked mud on the salt flats of the Little Rann of Kutch, Gujarat, India, 2006

Pete Oxford / Jeep and cracked mud on the salt flats of the Little Rann of Kutch, Gujarat, India

Pete Oxford / Cracked mud on the salt flats of the Little Rann of Kutch, Gujarat, India

Mike Potts / Panoramic view of Conwy estuary at low tide with mud flats, Gwynedd, North Wales, UK

David Noton / Maeddach estuary mud flats at dawn Dolgellau, Wales, UK

Jim Hallett / Mud flats at sunset, Brue / Parrett Estuary Somerset, England, UK.

Jabruson / Dry alkaline lake shore on Soda mud flats, Lake Nakuru, Kenya, East-Africa

Jason Smalley / Channel running through mudflats into estuary, Morecambe Bay at Silverdale, Lancashire, UK

Yva Momatiuk & John Eastcott / Bald Eagle (Haliaeetus leucocephalus) finds a small fish on mud-flats at low-tide, spring, south central Alaska

Yva Momatiuk & John Eastcott / Bald Eagle (Haliaeetus leucocephalus) adult eating small fish on mud flats at low tide, spring, south central Alaska

Yva Momatiuk & John Eastcott / Bald Eagle (Haliaeetus leucocephalus) adult walking on mud-flats at low-tide, spring, south central Alaska

Yva Momatiuk & John Eastcott / Bald Eagle (Haliaeetus leucocephalus) adult on mud-flats at low-tide, spring, south central Alaska

Yva Momatiuk & John Eastcott / Bald Eagle (Haliaeetus leucocephalus) adult on mud-flats at low-tide, spring, south central Alaska

Matthias Breiter / Western Sandpiper (Calidris mauri) feeding on tidal flats, Cordova, Alaska

Matthias Breiter / Grizzly Bear (Ursus arctos horribilis) tracks filled with water on mud flats, Katmai National Park, Alaska

Michael Quinton / Western Sandpiper (Calidris mauri) flock foraging in mud flats for small clams, crustaceans and marine invertebrates during spring migration stop-over at the Copper River Delta, Alaska

Niall Benvie / European wigeon drake feeding on mud flats (Ansas penelope) UK Scotland, Montrose Basin

Paul Johnson / The Wash estuary, Norfolk, England

Colin Monteath / Braided streams across mud flats, Patagonia, Argentina

Matthias Breiter / Grizzly Bear (Ursus arctos horribilis) juveniles on mud flats, Katmai National Park, Alaska

Matthias Breiter / Grizzly Bear (Ursus arctos horribilis) juveniles on mud flats, Katmai National Park, Alaska

David Woodfall / Glasswort (Salicornia) colonising mud flats of the Severn estuary, England, UK April 2010

David Woodfall / Old sewage pipe running across mud flats of Severn Estuary, Gloucestershire, England, UK April 2010

Flip de Nooyer / Photographer walking on mud-flats with hide, Wadden Sea, Netherlands

Mike Read / Mud flats at low tide Bridge to Ile de Noirmoutier Poitou Charente France