John Chan / California brown pelicans (Pelecanus occidentalis californicus) roosting on a mudflat, with a flock of Elegant terns (Thalasseus elegans) nearby, Southern California, USA May/2019

John Shaw / Brown bear (Ursus arctos) searching for clams on tidal mudflat with waterbirds. Lake Clark National Park, Alaska. August.

John Chan / Western gull (Larus occidentalis) feeding on a California two-spot octopus (Octopus bimaculoides) on a mudflat at low tide, Southern California, USA, November.

SCOTLAND: The Big Picture / Panning shot of a large flock of Pink-footed geese (Anser brachyrhynchus) taking off from their roosting site, Montrose, Angus, Scotland, UK, November.

Terry Whittaker / 2020VISION / Common / Harbour seals (Phoca vitulina) hauled out on mudflats at saltmarsh, Wallasea Island RSPB reserve, Essex, UK, March 2011

Anup Shah / Troop of Proboscis Monkeys (Nasalis larvatus) walking on their hindlegs through the mudflats revealed at low tide. Bako National Park, Sarawak, Borneo, Malaysia, March 2010.

Laurie Campbell / Bar-tailed godwit (Limosa lapponica) feeding on tidal mudflat, Firth of Forth, Scotland, UK, February

Nick Upton / Wigeon (Anas penelope) swimming up a tidal creek as a high tide rises to cover the mudflats and salt marshes, Severn Estuary, Somerset, UK, January.

Nick Upton / Wigeon (Anas penelope) swimming up a tidal creek as a high tide rises to cover the mudflats, Severn Estuary, Somerset, UK, January.

Brian Bevan / Avocet (Recurvirostra avosetta) feeding in evening light, showing use of upturned bill, Lincolnshire, England, UK, June.

Brian Bevan / Pair of Avocets (Recurvirostra avosetta) courting and mating, Lincolnshire, England, UK, June.

Nigel Cattlin / Mudflats of Chichester Channel at low tide, at sunset. Itchenor, West Sussex. November 2016.

Hanne & Jens Eriksen / Crab-plover (Dromas ardeola) three walking in a row on mudflat, two with food in beaks. Oman, June.

Mike Read / Ruff (Philomachus pugnax) feeding in mudflat at edge of lagoon. Titchwell Marsh RSPB Reserve, Norfolk, England, UK. September.

Mike Read / Red knot (Calidris canutus) flock in flight over mudflats at sunset. Snettisham RSPB Reserve, The Wash, Norfolk, England, UK. August 2018.

John Chan / California brown pelicans (Pelecanus occidentalis californicus) stretching their gular pouches and preening, resting near to a flock of Elegant terns (Thalasseus elegans), Southern California, USA, Ma...

John Chan / California brown pelicans (Pelecanus occidentalis californicus) roosting on a mudflat, with a flock of Elegant terns (Thalasseus elegans) nearby, Southern California, USA May/2019

John Chan / California brown pelicans (Pelecanus occidentalis californicus) roosting on a mudflat, with a flock of Elegant terns (Thalasseus elegans) nearby, Southern California, USA May/2019

John Chan / California brown pelicans (Pelecanus occidentalis californicus) roosting on a mudflat, with a flock of Elegant terns (Thalasseus elegans) nearby, Southern California, USA May/2019

John Chan / California brown pelicans (Pelecanus occidentalis californicus) roosting on a mudflat, with a flock of Elegant terns (Thalasseus elegans) nearby, Southern California, USA May/2019

John Chan / Elegant terns (Thalasseus elegans) gathering at their breeding grounds, taking flight, Southern California, USA, May.

John Chan / Elegant terns (Thalasseus elegans) gathering at their breeding grounds, Southern California, USA, May.

John Chan / Flock of Western sandpipers (Calidris mauri) foraging on a mudflat at low tide, Southern California, USA.

John Chan / Western gull (Larus occidentalis) feeding on a California two-spot octopus (Octopus bimaculoides) on a mudflat at low tide, Southern California, USA, November.

John Chan / Western gulls (Larus occidentalis) roosting on a mudflat, with Dowitchers (Scolopacidae) foraging nearby, Southern California, USA, April.

Ernie Janes / Grey plover (Pluvialis squatarola) on mudflats feeding, Norfolk, England, UK, January.

Remi Masson / Great blue spotted mudskipper (Boleophthalmus pectinirostris), two in territorial fight on mudflat. Kyushu Island, Japan. August.

Magnus Lundgren / Wild Wonders of China / Local people using salt to catch mollusks in the mud. This risks creating a unbalanced salinity in Ha Pak Nai wetlands, Yuen Long District facing Deep Bay, New territories, Hong Kong, China. June, 201...

Magnus Lundgren / Wild Wonders of China / River in Ha Pak Nai wetlands, Yuen Long District facing Deep Bay, New territories, Hong Kong, China.

Magnus Lundgren / Wild Wonders of China / Ha Pak Nai, a wetland area dominate by a mudflats, Yuen Long District, New territories, Hong Kong, China.

Magnus Lundgren / Wild Wonders of China / Staff from Ocean Park Conservation Fund, OPCF, and students visit Ha Pak Nai to see the juvenile Chinese horseshoe crabs, (Tachypleus tridentatus) Yuen Long District, New territories, Hong Kong, China...

Magnus Lundgren / Wild Wonders of China / Staff from Ocean Park Conservation Fund, OPCF, and students visit Ha Pak Nai to see the juvenile chinese horseshoe crabs (Tachypleus tridentatus) in a mudflats, Yuen Long District, Hong Kong, China.

Magnus Lundgren / Wild Wonders of China / Juvenile chinese horseshoe crab (Tachypleus tridentatus) Ha Pak Nai wetlands, Yuen Long District, Hong Kong, China.

Magnus Lundgren / Wild Wonders of China / Chinese horseshoe crab (Tachypleus tridentatus) juvenile, at Ha Pak Nai wetlands, Yuen Long District, Hong Kong, China. June, 2016.

Magnus Lundgren / Wild Wonders of China / Chinese horseshoe crab (Tachypleus tridentatus) juvenile held upside down in human hand, Ha Pak Nai wetlands, Yuen Long District, Hong Kong, China. June, 2016.

Magnus Lundgren / Wild Wonders of China / Old shells of Chinese horseshoe crab (Tachypleus tridentatus) Ha Pak Nai, Yuen Long District, Hong Kong, China.

Magnus Lundgren / Wild Wonders of China / Bluespotted mudskippers (Boleophthalmus pectinirostris) skipping along the beach, Hong Kong Wetland Park, Hong Kong, China.

Magnus Lundgren / Wild Wonders of China / Bluespotted mudskippers (Boleophthalmus pectinirostris) on mudflat, Hong Kong Wetland Park, Hong Kong, China.

Magnus Lundgren / Wild Wonders of China / Bluespotted mudskippers (Boleophthalmus pectinirostris) skipping along the beach, Hong Kong Wetland Park, Hong Kong, China.

Magnus Lundgren / Wild Wonders of China / Fiddler crab (Uca) male, hiding in an old shell at Ha Pak Nai mudflat, Yuen Long District, Hong Kong, China.

Magnus Lundgren / Wild Wonders of China / Fiddler crab (Uca) male, hiding in an old shell at Ha Pak Nai mudflat, Yuen Long District, Hong Kong, China.

Magnus Lundgren / Wild Wonders of China / Chinese egret (Egretta eulophotes) Ha Pak Nai, Yuen Long District, Hong Kong, China.

Magnus Lundgren / Wild Wonders of China / Barnacles and oysters on mangrove in Ha Pak Nai, a mudflat in the Yuen Long District, Hong Kong, China.

Matthew Maran / Redshank (Tringa totanus) feeding on mudflats, Otter Estuary at low tide. Devon, England, UK, February.

Konrad Wothe / Lugworm / Sandworm (Arenicola marina) holes and casts on mudflats, on the coast of the North Sea, Germany, June.

Nick Hawkins / Semipalmated sandpiper (Calidris pusilla) flock feeding on mudflats, Johnson's Mills, Bay of Fundy, New Brunswick, Canada, July.

Mike Potts / Banded plover (Charadrius falklandicus) two feeding on a mudflat. Port Stanley, Falkland Islands. January.

Tui De Roy / American flamingo (Phoenicopterus ruber) pair in courtship, group of three feeding, Punta Cormorant, Floreana Island, Galapagos