Cyril Ruoso / Chimpanzee (Pan troglodytes) adult female with orphan baby she has adopted, Gabon

Mark Taylor / Tabby kittens, Stanley and Fosset, 3 months old, sitting and snuggling together.

Mitsuaki Iwago / Giant Panda (Ailuropoda melanoleuca), three captive bred cubs, China

Ingo Arndt / European River Otter (Lutra lutra) sisters resting, Europe

Ingo Arndt / European River Otter (Lutra lutra) sisters resting, Europe

Matthias Breiter / Polar Bear (Ursus maritimus) female with twelve week old cub, Canada

Matthias Breiter / Polar Bear (Ursus maritimus) mother with cub, Churchill, Manitoba, Canada

Michio Hoshino / Polar Bear (Ursus maritimus) cub nuzzling mother, Churchill, Manitoba, Canada

Ingo Arndt / Puma (Puma concolor) female and two cubs snuggling on hillside. Torres del Paine, Patagonia, Chile. July 2017.

Cyril Ruoso / Ringed-tailed lemur (Lemur catta), two sitting and snuggling on branch. Granite mountain, Anja Community Reserve, Madagascar.

Karine Aigner / Grey langur / Hanuman langur (Semnopithecus sp) baby snuggling up to its mother. Ranthambore National Park, Rajasthan, India.

Ingo Arndt / Mountain Lion (Puma concolor) mother and cubs, Torres del Paine National Park, Patagonia, Chile

Martin Willis / Red-legged Pademelon (Thylogale stigmatica) juvenile and mother snuggling, Malanda, Queensland, Australia

David Pattyn / Verreaux's sifaka (Propithecus verreauxi) pair snuggling close together to prepare for the cold night ahead, Berenty Private Reserve, southern Madagascar.

Nick Upton / Samantha Pickering with a Noctule bat (Nyctalus noctula) snuggling into the collar of her fleece at her rescue centre, North Devon Bat Care, Devon, UK, October 2015. Model released.

Mark Raycroft / Whippet (Canis familiaris) parent and puppy

Richard Du Toit / Burchell's Zebra (Equus burchellii) mother grazing with foal, Rietvlei Nature Reserve, South Africa

Suzi Eszterhas / Hoffmann's Two-toed Sloth (Choloepus hoffmanni) orphaned baby clinging to stuffed animal, Aviarios Sloth Sanctuary, Costa Rica

Suzi Eszterhas / Coquerel's Sifaka (Propithecus coquereli) young, Duke Lemur Center, North Carolina

Roland Seitre / Geoffroy's Cat (Leopardus geoffroyi) pair, native to South America

Mark Taylor / Birman-cross mother cat snuggling up to her kitten, against white background

Mark Taylor / Ginger Guinea pig and blue-grey floppy-eared rabbit snuggling together, against white background

Richard Du Toit / Burchell's Zebra (Equus burchellii) resting its head on the back of another, Rietvlei Nature Reserve, Gauteng, South Africa

Mark Taylor / Puppy love - Golden Cocker Spaniel puppy, Maizy, snuggling up to a red F1b Goldendoodle puppy.

Mark Taylor / Puppy love - Golden Cocker Spaniel puppy, Maizy, snuggling up to a red F1b Goldendoodle puppy.

Aflo / ic-05202 Two puppies sitting

Konrad Wothe / Polar Bear (Ursus maritimus) mother with two cubs sleeping in the snow, Churchill, Manitoba, Canada

Suzi Eszterhas / Antarctic Fur Seal (Arctocephalus gazella) mother and 1 to 2 week old pup, Prion Island, South Georgia

Suzi Eszterhas / Cheetah (Acinonyx jubatus) mother and 7 to 9 month old cub, Masai Mara National Reserve, Kenya

Suzi Eszterhas / Cheetah (Acinonyx jubatus) 4 to 5 month old cub snuggled up to its mother, vulnerable, Ngorongoro Conservation Area, Tanzania

Suzi Eszterhas / Cheetah (Acinonyx jubatus) older cubs, vulnerable, Ngorongoro Conservation Area, Tanzania, east Africa

Suzi Eszterhas / Cheetah (Acinonyx jubatus) nine day old cubs curled up together in nest, Maasai Mara Reserve, Kenya

Suzi Eszterhas / Cheetah (Acinonyx jubatus) nine day old cubs curled up together in nest, Maasai Mara Reserve, Kenya

Suzi Eszterhas / Spotted Hyena (Crocuta crocuta) mother and affectionate 12 to 14 week old cub, Masai Mara National Reserve, Kenya

Suzi Eszterhas / Spotted Hyena (Crocuta crocuta) mother and affectionate 12 to 14 week old cub, Masai Mara National Reserve, Kenya

Suzi Eszterhas / Spotted Hyena (Crocuta crocuta) 34 day old cub resting with mother, Masai Mara National Reserve, Kenya

Suzi Eszterhas / Spotted Hyena (Crocuta crocuta) 10 to 12 week old cub with mother, Masai Mara National Reserve, Kenya

Suzi Eszterhas / African Lion (Panthera leo) mother resting with four week old cub, vulnerable, Masai Mara National Reserve, Kenya

Suzi Eszterhas / African Lion (Panthera leo) six to seven week old cub sleeping against mother, vulnerable, Masai Mara National Reserve, Kenya

Matthias Breiter / Polar Bear (Ursus maritimus) three month old cub cuddles up to mother in lee of willows, vulnerable, Wapusk National Park, Manitoba, Canada

Matthias Breiter / Polar Bear (Ursus maritimus) three month old cub interrupts nursing to look around second cub continues to nurse, vulnerable, Wapusk National Park, Manitoba, Canada

Matthias Breiter / Polar Bear (Ursus maritimus) trio of three month old cubs and mother snuggling, vulnerable, Wapusk National Park, Manitoba, Canada

Matthias Breiter / Polar Bear (Ursus maritimus) trio of three month old cubs and mother resting among white spruce, vulnerable, Wapusk National Park, Manitoba, Canada

Matthias Breiter / Polar Bear (Ursus maritimus) trio of three month old cubs and mother among white spruce, cubs playing and climbing on mother, vulnerable, Wapusk National Park, Manitoba, Canada

Jane Burton / Red silver Turkish Angora cat and sandy Lop Rabbit snuggling together.

Jan Vermeer / Wild Boar (Sus scrofa) piglets snuggled and sleeping on sow

Winfried Wisniewski / Galapagos Sea Lion (Zalophus wollebaeki) mother and pup snuggling on beach, Galapagos Islands, Ecuador

Hiroya Minakuchi / Southern Elephant Seal (Mirounga leonina) mother and pup, Falkland Islands

Sumio Harada / Bighorn Sheep (Ovis canadensis) mother and baby resting together, Rocky Mountains, North America

Konrad Wothe / Polar Bear (Ursus maritimus) mother with two cubs, Churchill, Manitoba, Canada

Konrad Wothe / Polar Bear (Ursus maritimus) mother with two cubs, Churchill, Manitoba, Canada

Thomas Mangelsen / Polar Bear (Ursus maritimus) mother and cubs, Churchill, Manitoba, Canada

Tui De Roy / Waved Albatross (Phoebastria irrorata) guarding young chick, Punta Cevallos, Espanola Island, Galapagos Islands, Ecuador

Michio Hoshino / Polar Bear (Ursus maritimus) cubs huddle with mother for warmth, Churchill, Manitoba, Canada

Michio Hoshino / Polar Bear (Ursus maritimus) mother and cubs nestled together, Churchill, Manitoba, Canada

Mitsuaki Iwago / Domestic Cat (Felis catus) mother and infant kitten resting together

Suzi Eszterhas / Giant Panda (Ailuropoda melanoleuca) six-to-eight month old cub resting on mother, Chengdu, China

Suzi Eszterhas / Western Gray Squirrel (Sciurus griseus) three week old orphaned baby snuggling with Eastern Fox Squirrel (Sciurus niger) baby, WildCare, San Rafael, California

Tui De Roy / Swallow-tailed Gull (Creagrus furcatus) parent with chick under wing, Plazas Island, Galapagos Islands, Ecuador

Suzi Eszterhas / Bengal Tiger (Panthera tigris tigris) mother grooming eight week old cub at den, Bandhavgarh National Park, India

Suzi Eszterhas / Bengal Tiger (Panthera tigris tigris) mother grooming eight week old cub at den, Bandhavgarh National Park, India

Suzi Eszterhas / Bengal Tiger (Panthera tigris tigris) mother nuzzling eight week old cub at den, Bandhavgarh National Park, India

Suzi Eszterhas / Bengal Tiger (Panthera tigris tigris) six week old cub snuggling up to sleeping mother at den, Bandhavgarh National Park, India

Martin Willis / Silvereye (Zosterops lateralis) a pair snuggle together on a branch, Mount Barker, South Australia, Australia

Martin Willis / Red-legged Pademelon (Thylogale stigmatica) female and joey snuggling together, Atherton Tableland, Queensland, Australia

Matthias Breiter / Polar Bear (Ursus maritimus) trio of three month old cubs resting with resting mother amid white spruce, vulnerable, Wapusk National Park, Manitoba, Canada

Matthias Breiter / Polar Bear (Ursus maritimus) trio of three month old cubs resting with resting mother amid white spruce, vulnerable, Wapusk National Park, Manitoba, Canada

Matthias Breiter / Polar Bear (Ursus maritimus) two three month old cubs snuggling with resting mother amid white spruce, vulnerable, Wapusk National Park, Manitoba, Canada

Matthias Breiter / Polar Bear (Ursus maritimus) two three month old cubs snuggling with resting mother amid white spruce, vulnerable, Wapusk National Park, Manitoba, Canada

Matthias Breiter / Polar Bear (Ursus maritimus) two three month old cubs and mother resting, vulnerable, Wapusk National Park, Manitoba, Canada

Matthias Breiter / Polar Bear (Ursus maritimus) three month old cubs and mother resting, vulnerable, Wapusk National Park, Manitoba, Canada

Matthias Breiter / Polar Bear (Ursus maritimus) trio of three month old cubs and mother among white spruce, cubs playing and climbing on mother, vulnerable, Wapusk National Park, Manitoba, Canada

Matthias Breiter / Polar Bear (Ursus maritimus) trio of three month old cubs and mother among white spruce, cubs playing and climbing on mother, vulnerable, Wapusk National Park, Manitoba, Canada

Sylvain Cordier / Pallas's cat (Otocolobus manul), mother with kittens, snuggling together. East Mongolia. July.

Sylvain Cordier / Pallas's cat (Otocolobus manul), mother with kittens, snuggling together. East Mongolia. July.

Sylvain Cordier / Pallas's cat (Otocolobus manul), mother with kittens, snuggling together, showing striped tail. East Mongolia. July.

Steve Gettle / Dwarf Mongoose (Helogale parvula) pair, Samburu National Reserve, Kenya

Suzi Eszterhas / Leopard (Panthera pardus) mother and six-week-old cub, Sabi-sands Game Reserve, South Africa

Suzi Eszterhas / Tasmanian Devil (Sarcophilus harrisii) seven-month-old joey at den, Trowunna Wildlife Sanctuary, Tasmania, Australia

Suzi Eszterhas / Tasmanian Devil (Sarcophilus harrisii) seven-month-old joeys in den, Trowunna Wildlife Sanctuary, Tasmania, Australia

Suzi Eszterhas / Tasmanian Devil (Sarcophilus harrisii) mother and seven-month-old joeys at den, Trowunna Wildlife Sanctuary, Tasmania, Australia

Suzi Eszterhas / Tasmanian Devil (Sarcophilus harrisii) mother and seven-month-old joeys at den, Trowunna Wildlife Sanctuary, Tasmania, Australia

Suzi Eszterhas / Tasmanian Devil (Sarcophilus harrisii) mother and seven-month-old joeys at den, Trowunna Wildlife Sanctuary, Tasmania, Australia

Suzi Eszterhas / Tasmanian Devil (Sarcophilus harrisii) mother and six-month-old joey at den, Trowunna Wildlife Sanctuary, Tasmania, Australia

Suzi Eszterhas / Walrus (Odobenus rosmarus) mother and calf, Svalbard, Norway

Suzi Eszterhas / Meerkat (Suricata suricatta) two-week-old pups resting in den with parents, Makgadikgadi Pans, Botswana

Mark Raycroft / Rottweiler (Canis familiaris) puppies, North America

Joel Sartore / Photo Ark / Twin giant panda cubs (Ailuropoda melanoleuca) Mei Lun and Mei Huan, the at Zoo Atlanta.