Stephen Belcher / Signs for annual red crab migration, Christmas Island, Australia

Stephen Belcher / Christmas Island Red Crab (Gecarcoidea natalis) with road sign in the background, Christmas Island, Australia

Stephen Belcher / Christmas Island Red Crab (Gecarcoidea natalis) crossing the road with sign in the background, Christmas Island, Australia

Stephen Belcher / Christmas Island Red Crab (Gecarcoidea natalis) group crossing road during annual migration, Christmas Island, Australia

Stephen Belcher / Christmas Island Red Crab (Gecarcoidea natalis) group crossing road during annual migration, Christmas Island, Australia

Yva Momatiuk & John Eastcott / Teakettle Junction post decorated with kettles by tourists, Death Valley National Park, California

Oriol Alamany / Road sign warning of Kangaroos crossing, Stuart Highway, near Coober Pedy, South Australia, Australia, November

Tony Phelps / Snake crossing warning sign "Give us a brake" next to road, DeHoop, Western Cape, South Africa

Steven David Miller / Sign warning travellers of Bilbies {Macrotis sp} on Peron Road, Francois Peron National Park, Western Australia, November

Steven David Miller / A sign warns drivers to watch for passing Malle fowl; one of the species that has been reintroduced to the park under Project Eden, Peron Road, Francois Peron National Park, Western Australia

Paul Hobson / Pink road sign on Isle of Mull, Inner Hebrides, Scotland, UK

Jouan & Rius / "Beware of Kangaroos" road sign, Flinders Ranges National Park, South Australia, Australia

Jouan & Rius / "Beware of Kangaroos" road sign, Flinders Ranges National Park, South Australia, Australia

Jouan & Rius / Road sign in Central Australia Desert with distances to various cities, Northern Territory, Australia

Ben Osborne / Warning sign for Road closure due to coastal erosion undermining the cliff, Yorkshire, UK

Ben Osborne / Warning sign for Road closure due to coastal erosion undermining the cliff, Yorkshire, UK

Ben Osborne / Warning sign for Road closure due to coastal erosion undermining the cliff, Yorkshire, UK

Jouan & Rius / 'Beware of Koalas' road sign, Australia

Jouan & Rius / Sign warning of the danger of sand on the road, Namib desert, Namibia

Theo Allofs / Road sign warning of crossing Camels, Koalas and Kangaroos, Australia

Juergen Freund / Cassowary protection warning road sign, Western Australia

Richard Du Toit / Beware of fox road sign near Kgalagadi Transfrontier Park, South Africa

Richard Du Toit / Beware of animals road sign, South Africa

Juergen Freund / Road warning sign regarding cassowaries, Queensland, Australia

Rob Tilley / Queets River Road, entrance sign to Olympic National Park, Washington, USA. July 2002

Pete Oxford / 'Beware of Kangaroos' crossing road sign, Australia

Richard Du Toit / Beware of Tortoise road sign, West Coast National Park, South Africa

Richard Du Toit / Road, Itala Game Reserve, South Africa

David Noton / Road hazard sign (beware of moose), Gros Morne National Park, Newfoundland, Canada

Colin Seddon / Sheep warning road sign, Dumfrieshire, Scotland, UK

Colin Seddon / Badger warning road sign, Scotland, UK

Colin Seddon / Road sign warning about European river otters (Lutra lutra) crossing the road, UK

Jose B. Ruiz / Walking path sign at the side of road, La Focella, Teverga, Asturias, Spain.

Ingo Arndt / Sign warning about bison, Yellowstone National Park, Wyoming

Richard Du Toit / 'Dung beetles have right of way' warning road sign, Addo NP, South Africa

Mark Raycroft / Moose (Alces alces americana) crossing sign along highway, Newfoundland, Canada

Colin Seddon / Otter crossing warning road sign, Shetland Isles, Scotland, UK

Solvin Zankl / Road sign warning of European river otter {Lutra lutra} Shetland Islands, Scotland, UK

Pete Oxford / Chameleon road crossing warning sign, Madagascar

Richard Du Toit / Beware of Animals crossing warning sign on road, South Africa

Richard Du Toit / African elephant road warning sign, Chobe NP, Botswana

Philippe Clement / Warning sign on road in Denali NP, chewed by grizzly bears and exposing nails, Alaska, USA.

Steven David Miller / Road crossing sign for Florida gopher tortoise {Gopherus polyphemus} Florida, USA - endangered species

Staffan Widstrand / Moose warning road sign, Sweden.

Daniel Gomez / A road sign in Sian Ka'an Biosphere Reserve, Mexico.

Toby Sinclair / Rhinoceros warning sign on road in Animal Corridor, Kaziranga National Park, India

Toby Sinclair / Elephant warning sign on road in Animal Corridor, Kaziranga National Park, Assam, India

Richard Du Toit / Beware Penguin road sign, Simonstown, South Africa

Richard Du Toit / Beware of Tortoise road sign, West Coast NP, South Africa

Richard Du Toit / Hippopotamus (Hippopotamus amphibius) warning sign along road near Nelspruit, South Africa

Richard Du Toit / Rhinoceros (Diceros sp) warning sign along side of the road, Phinda Game Reserve, South Africa

Richard Du Toit / Cape Warthog (Phacochoerus aethiopicus) warning sign along side of main road, Namibia

Richard Du Toit / African Elephant (Loxodonta africana) road sign warning drivers of elephants crossing, near Kasane, Botswana

Richard Du Toit / Dung Beetle (Scarabaeidae) road sign cautioning drivers that Dung Beetles have the right of way, Itala Game Reserve, South Africa

Richard Du Toit / Dung beetle road crossing warning sign. Itala Game Reserve, South Africa

Mark Moffett / Sign warning drivers to watch for rare endangered Dung Beetles on road, South Africa

Gavin Hellier / Traffic lights with walk sign lit, next to Gaudi's La Sagrada Familia, Barcelona, Catalunya, Spain

Yva Momatiuk & John Eastcott / Stop sign on dirt road leading to Alyeska oil pipeline, North Slope, Alaska

Yva Momatiuk & John Eastcott / Stop sign on dirt road leading to Alyeska oil pipeline, North Slope, Alaska

Gerry Ellis / Wildlife caution road signs in the foothills of the Great Dividing Range, New South Wales, South Australia

Norbert Wu / Whale watching sign, migrating Gray Whales draw many tourists each year, Magdalena Bay, Baja California, Mexico

Norbert Wu / Sea Wasp (Chironex fleckeri) warning sign notifying swimmers that sting can be fatal, Queensland, Australia

Norbert Wu / Kangaroo, Tiger Quoll, and Emu road sign in rainforest habitat, Queensland, Australia

Norbert Wu / Koala (Phascolarctos cinereus) road sign, Queensland, Australia

Norbert Wu / Road sign for Sea Turtle crossing, highway is too close to beach, turtles cross road to dig nests, Maui, Hawaii

Tui De Roy / Sign posted 'Birds Only Beyond This Point', Midway Atoll, Hawaii

Tui De Roy / Department of Conservation places warning road signs in an effort to minimize road kills of endangered national bird, Tongariro National Park, New Zealand

Elizabeth White / Sign warning of animals crossing road, Western Australia

Steven David Miller / Sign warning motorists of animals on the road, Eyre Highway S. Australia. Camel

Hermann Brehm / Entrance sign across road to the Pantanal, Brazil

Tim Edwards / 'Give Moose a Brake' road sign on outskirts of Anchorage, Alaska

Juergen Freund / A sign for crab migration crossing - 'Avoid using this road'. Christmas Island

Gavin Hellier / Wedding Chapel sign on the Strip, Las Vegas, Nevada, USA

Richard Du Toit / Hippopotamus crossing warning sign beside road. Nelspruit, South Africa

Richard Du Toit / Warthog {Phacochoerus aethiopicus} road warning sign. South Africa

Pete Cairns / Road sign indicating position of Arctic Circle, Norway

Sebastian Kennerknecht / Road and livestock trails dissecting cloud forest, Hawf Protected Area, Yemen

Mike Read / New Forest National Park road sign in snow with New Forest pony in the background, Moyles Court, near Ringwood, Hampshire, UK, April 2008

Colin Monteath / Minefield road sign, Falkland Islands

Juergen Freund / Warning sign to drive slow over humps and to be aware of endangered cassowaries crossing the road. A prankster drew a dead cassowary over the hump sign, saying before and after. Daintree National Park...

Ingo Arndt / Entrance to Torres del Paine National Park, Patagonia, Chile

Michael Durham / Weed control signage along Highway 82, Wallowa County, listing introduced plants that have become invasive weeds, Oregon

Colin Monteath / Shahtoosh poster discouraging killing Chiru for their highly prized wool, World Wildlife Federation, Ladakh, northwest India

Colin Monteath / Road sign illustrating protected Ladakh wildlife including Brown Bear, Chiru, Ibex and Shapo, near Leh, Ladakh, northwest India

WILLIAM OSBORN / Road sign warning of Mallee fowl {Leipoa ocellata} Little Desert NP, Victoria, Australia