Doug Allan / Emperor penguin males incubating eggs huddle for warmth at -40 degrees centigrade, winter, Antarctica. Green is excrement on snow. {Aptenodytes forsteri}

David Tipling / Emperor Penguins, (Aptenodytes forsteri), young huddling together to form a creche to keep warm, during storm, Dawson Lambton Glacier, Weddell Sea, Antarctica

David Tipling / King Penguins (Aptenodytes patagonicus) group huddled together in blizzard, Right Whale Bay, South Georgia, November

David Tipling / King Penguins (Aptenodytes patagonicus) group huddled together in storm, Right Whale Bay, South Georgia, November

Tui De Roy / Volcan Alcedo giant tortoises (Chelonoidis nigra vandenburghi) wallowing in rain pools on caldera floor, possibly for thermoregulation or detering parasites, with sulphur fumaroles in background, Alce...

Martin Dohrn / Wood ant (Formica rufa) basking to absorb heat from the sun which is brought back to the nest when they return, Europe

Andy Rouse / Polar bear (Ursus arctos maritimus) mother rolling in snow watched by new year cubs, 6 months old, Svalbard, Arctic

Nick Upton / 2020VISION / Male Southern hawker dragonfly (Aeshna cyanea) sunning itself on Rose flower (Rosa sp.) in garden in autumn, Wiltshire, England, UK, October . Property released. Did you know? The Latin name for this...

Mark Hamblin / 2020VISION / Robin (Erithacus rubecula) adult perched in winter with feather fluffed up, Scotland, UK, December

Mary McDonald / White-headed Mousebirds (Colius leucocephalus) clustered together in tree to keep warm in the Upper Mara, Masai Mara Game Reserve, Kenya

Alex Mustard / Young Florida manatee (Trichechus manatus latirostrus) stays warm in a freshwater spring in winter, at dawn. Three Sisters Spring, Crystal River, Florida, USA. January

Dave Bevan / Robin (Erithacus rubecula) perched on snow-covered fence, feather fluffed up for warmth, Carmarthenshire, Wales, UK

Philip Dalton / Cheetah (Acinonyx jubatus) female with cub lying in shade under her body, Masai Mara, Kenya

Roger Powell / Dunlin {Calidris alpina} sunbathing / warming itself on heated river gravel, Glen Kingie, West-Inverness, Scotland, UK

Wild Wonders of Europe / Möllers / Male Western green lizard (Lacerta bilineata) warming up, San Marino, May 2009. WWE OUTDOOR EXHIBITION.

Wild Wonders of Europe / Schandy / Swallowtail butterfly (Papilio machaon) sunning on a riverbank in Arkhyz section of the Teberdinsky biosphere reserve, Caucasus, Russia, July 2008

Wild Wonders of Europe / Schandy / Swallowtail butterflies (Papilio machaon) sunning on a riverbank in Arkhyz section of the Teberdinsky biosphere reserve, Caucasus, Russia, July 2008

Juan Carlos Munoz / Galapagos giant tortoise {Geochelone elephantopus} cooling in water, Santa Cruz Island, Galapagos, January

Yukihiro Fukuda / Japanese macaque (Macaca fuscata) eight months old sitting in front of a pool created by a hot spring being used by females and young for bathing to keep warm, Jigokudani, Joshinetsu Kogen NP, Nagano...

Yukihiro Fukuda / Japanese macaques (Macaca fuscata) spread out sitting on small rocks, Shodoshima, Japan

Yukihiro Fukuda / Japanese macaques (Macaca fuscata) faces looking up, huddling together for warmth on a cold day, Shodoshima, Japan

Yukihiro Fukuda / Japanese macaques (Macaca fuscata) huddled together sleeping in a tree at night, full moon, Jigokudani, Joshinetsu Kogen NP, Nagano, Japan

Yukihiro Fukuda / Japanese macaques (Macaca fuscata) huddling together for warmth on a cold day, Shodoshima, Japan

Yukihiro Fukuda / Japanese macaques (Macaca fuscata) huddling together for warmth on a cold day, Shodoshima, Japan

Yukihiro Fukuda / Female Japanese macaques (Macaca fuscata) in a hot spring to keep warm, only females and young bathe, Jigokudani, Joshinetsu Kogen NP, Nagano, Japan

Yukihiro Fukuda / Japanese macaque (Macaca fuscata) holding young while bathing in hot spring to keep warm, only females and young bathe, winter, Jigokudani, Joshinetsu Kogen NP, Nagano, Japan

Yukihiro Fukuda / Japanese macaque (Macaca fuscata) family huddled together for warmth on a cold day, Jigokudani, Joshinetsu Kogen NP, Nagano, Japan

Yukihiro Fukuda / Two groups of Japanese macaques (Macaca fuscata) huddling together for warmth on a cold day, Shodoshima, Japan

Yukihiro Fukuda / Japanese macaques (Macaca fuscata) huddling together for warmth on a cold day, Shodoshima, Japan

Yukihiro Fukuda / Japanese macaques (Macaca fuscata) warming up by bathing in a hot spring during snowfall, only females and young bathe, Jigokudani, Joshinetsu Kogen NP, Nagano, Japan

Wild Wonders of Europe / Lesniewski / Alpine marmot (Marmota marmota) warming up on a rock, Hohe Tauern National Park, Austria, July 2008

Andy Rouse / African elephant (Loxodonta africana) rear view of large ear showing veins for efficient heat loss, Savute, Botswana (non-ex)

Anup Shah / Ring-tailed Lemur (Lemur catta) 'sunning' in the early morning light to warm themselves. Berenty Private Reserve, Madagascar. Oct 2008.

Inaki Relanzon / Ring-tailed lemur (Lemur catta) group sitting on ground, sunning in morning sun, Berenty private reserve, south Madagascar

Yukihiro Fukuda / Japanese macaque / Snow monkey {Macaca fuscata} monkey basking in the winter sunshine, Jigokudani, Nagano, Japan

Yukihiro Fukuda / Japanese macaque / Snow monkey {Macaca fuscata} 7-month-old monkey bathing in hot springs, examining its hands, water at 40 degrees, Jigokudani, Nagano, Japan

Yukihiro Fukuda / Japanese macaque / Snow monkey {Macaca fuscata} two monkeys huddle together to keep warm, Jigokudani, Nagano, Japan

Yukihiro Fukuda / Japanese macaque / Snow monkey {Macaca fuscata} adult female bathing in hot springs tapping the water surface with hand in play, water at 40 degrees, Jigokudani, Nagano, Japan

Yukihiro Fukuda / Japanese macaque / Snow monkey {Macaca fuscata} group of monkeys bathing in hot springs, water at 40 degrees, Jigokudani, Nagano, Japan

Frederique Olivier / Emperor penguin {Aptenodytes forsteri} chicks huddled together for warmth during snow storm, Antarctica

Igor Shpilenok / Steller's sea eagle {Haliaeetus pelagicus} sunning on tree top, Kuril Lake, Kamchatka, Far East Russia

Igor Shpilenok / Kamchatka brown bear (Ursus arctos beringianus) enjoys hot steam from a geyser in Valley of the Geysers, Kronotsky Zapovednik, Kamchatka, Far East Russia

Hanne & Jens Eriksen / Isabelline wheatear {Oenanthe isabellina} panting in heat, Khatmat Milahah, Oman.

Anup Shah / Family of young Rock hyrax {Procavia capensis} sunning on rock, Serengeti NP, Tanzania

Jose B. Ruiz / Common / House sparrow {Passer domesticus} male perching on stone with feathers ruffled, Quintana de la Serena, Badajoz, Extremadura, Spain April

Luiz Claudio Marigo / Hoatzins basking in sun {Ophisthocomus hoazin} Amazonas, Brazil

Jean-Pierre Zwaenepoel / Rhesus macaques {Macaca mulatta} huddled on branch for warmth at dawn, Keoladeo Ghana NP, Rajasthan, India

Doug Wechsler / Red bellied turtle male sunning {Pseudemys rubriventris} New Jersey, USA

Pete Oxford / Black caiman basking with butterfly on snout {Caiman niger} Manu National Park, Peru

Doug Wechsler / Florida red bellied turtle {Pseudemys nelsoni}basking & stretching, Big Cypress NP FloridA

Luiz Claudio Marigo / White backed vultures sunning {Gyps africanus} Samburu GR, Kenya

Luiz Claudio Marigo / Hoatzins basking in sun {Ophisthocomus hoazin} Amazonas, Brazil

Mark Yates / Wild cat sunning on rocks {Felis silvestris} female Perthshire, Scotland, UK

Gabriel Rojo / Argentine grey fox sunning {Pseudolopex griseus} Patagonia, Argentina

Pete Oxford / Anaconda sunbathing {Eunectes murinus} Cerrado habitat, Piaui state, Brazil

TOM MANGELSEN / Northern cardinal fluffed up in tree. (Cardinalis cardinalis) Montana

Ingo Arndt / Japanese macaques grooming in hot thermal spring {Macaca fuscata} Joshin-etsu NP, Japan. These primates can survive winter temperatures below -15 degrees by bathing in the springs

Rolf Nussbaumer / Turkey vulture sunning and calling in tree {Cathartes aura} Texas, USA.

Anup Shah / Young female tigers cool off in waterhole (Panthera tigris) Ranthambhore NP India

Hanne & Jens Eriksen / Rockhopper penguin on rock {Eudyptes chrysocome} Falkland Islands

John Downer / Thermograph of human hand

SIMON KING / Young Meerkats huddling together {Suricata suricatta} Tswalu Kalahari Reserve S Africa

Colin Seddon / Slow worm (Anguis fragilis) on rock. England, UK, Europe

Jabruson / Termite mound cooling chimneys - savanna near Mboko, Odzala National Park, Democratic Republic of Congo.

Andrew Cooper / Adder basking in sun along coast, Devon, UK

Doug Allan / Two-week-old Emperor penguin chick sits on parent's feet under brood pouch for warmth {Aptenodytes forsteri} Antarctica

Terry Andrewartha / Grey heron sunning {Ardea cinerea} UK

Tony Heald / Southern savanna (Rock) monitor {Varanus albigularis} panting Etosha NP, Namibia

HUW CORDEY / Chuckwalla lizard sunning {Sauromalus obesus} Grand Canyon, AZ, USA

David Pike / Japanese macaques warming up and grooming in hot pools {Macaca fuscata} Jigokudani, Japan

David Tipling / Emperor penguin chicks {Aptenodytes forsteri} huddled together for warmth, Weddell Sea, Antarctica

David Tipling / Emperor penguin chick {Aptenodytes forsteri} brooding on adults feet calling for food, Weddell Sea, Antarctica

David Tipling / Adult Emperor penguin {Aptenodytes forsteri} with chick at feet huddling for warmth, Weddell Sea, Antarctica

Anup Shah / White Tiger head portrait reflected in water {Panthera tigris} captive, India

David Tipling / Emperor Penguins, (Aptenodytes forsteri), chicks huddled together in a creche to keep warm, Weddell Sea, Antarctica

David Tipling / Emperor Penguins, (Aptenodytes forsteri), young huddling together to form a creche to keep warm, during storm, Dawson Lambton Glacier, Weddell Sea, Antarctica

Nick Upton / Female Celery fly (Euleia heraclei) sunbasking on a leaf, Wiltshire garden, UK, April.

Nick Upton / Thick-headed fly / Wasp fly / Conopid fly (Myopa sp.) a parasite of bees, sunbasking on a leaf, Wiltshire garden, UK, April.

Staffan Widstrand / Polar Bear (Ursus maritimus) rolling around on snow and ice, Svalbard, Norway

Suzi Eszterhas / Southern sea otters (Enhydra lutris) trying to keep paws dry for thermoregulation by holding above water surface, Monterey Bay, California, USA

Fergus Gill / 2020VISION / Tree sparrow (Passer montanus) on ground ruffling feathers, Perthshire, Scotland, UK, July.

Tony Heald / African elephant (Loxodonta africana) baby wallowing in mud, Mana Pools National Park, Zimbabwe October 2012

Tony Heald / Nile Crocodile (Crocodylus niloticus) on riverbank with gaping mouth, most likely to cool down, Hwange National Park, Zimbabwe October 2012

Staffan Widstrand / Polar Bear (Ursus maritimus) stretching out in snow, Svalbard, Norway

XI ZHINONG / Tibetan pika (Ochotona thibetana) group in the snow, Sanjiangyuan, Qinghai, China, Decemeber

Mark Carwardine / Argentine horned / ornate frog (Ceratophrys ornata) sitting in water, captive.

Mark Carwardine / Gila monster resting in shade {Heloderma suspectum} California, USA

Andrew Parkinson / Bengal Tiger (Panthera tigris) sub-adult, approximately 17-19 months old, cools off by lying in a secluded forest pool. Endangered. Bandhavgarh National Park, India. Non-ex.

Andrew Parkinson / Bengal Tiger (Panthera tigris) sub-adult, approximately 17-19 months old, cools off by lounging in a secluded forest pool. Endangered. Bandhavgarh National Park, India. Non-ex.

Christophe Courteau / African elephant (Loxodonta africana) with muddy face and trunk, Okavango Delta, Botswana

Christophe Courteau / Hamadryas Baboon {Papio hamadryas} male and female resting in the shade. Awash NP, Ethiopia

Christophe Courteau / Spectacled Caiman / Jacare (Caiman crocodilus) 'panting' to cool down on river bank. Pantanal, Brazil.

Christophe Courteau / Great blue heron sunning {Ardea herodias} Galapagos.

Christophe Courteau / Flightless cormorant {Nannopterum harrisi} Fernandina Is, Galapagos.

Steven Kazlowski / Polar bear (Ursus maritimus) pair of adults rest and stay cool on the newly formed pack ice in autumn, 1002 area of the Arctic National Wildlife Refuge, North Slope, Alaska, USA