Danny Green / Arctic fox (Alopex lagopus) following scent, in winter pelage. Svalbard, Norway. April.

Steven David Miller / A Perentie (Varanus giganteus) using its forked tongue to detect smells, Alice Springs Reptile Centre, Northern Territory, Australia, Captive. May.

Andy Rouse / Bengal tiger (Panthera tigris) tigress Arrowhead sniffing tree for scent, Ranthambhore, India

Michael Hutchinson / Close-up of a European hedgehog (Erinaceus europaeus) sniffing, Bristol, England, UK, 2016.

Luke Massey / Low angle shot of Wild boar (Sus scrofa) piglets running towards parent, Forest of Dean, Gloucestershire, England, UK, May.

Sandesh Kadur / Bengal monitor (Varanus bengalensis) smelling a stone with its tongue, Ranthambore National Park, Rajasthan, India. 2016.

Tony Phelps / Cape cobra (Naja nivea) emerging from a Cape gerbil (Gerbilliscus afra) burrow, hunting and smelling with its tongue, De Hoop Nature Reserve, Western Cape, South Africa, January.

Silke Arndt / Western rattlesnake (Crotalus viridis viridis), threat display, South Dakota, USA, September.

John Cancalosi / Western diamondback rattlesnake (Crotalus atrox), defensive rattling, Arizona, USA, April.

SCOTLAND: The Big Picture / Red Squirrel (Sciurus vulgaris) close-up portrait of red squirrel sniffing. Cairngorms National Park, Highlands, Scotland, UK, March.

Mark Raycroft / Black Labrador Retriever (Canis familiaris) puppy sniffing flower

Wim van den Heever / Lion (Panthera leo) male standing in cold and rain with strong wind blowing, smelling the air, Masai Mara National Reserve, Kenya