Edwin Giesbers / Female Orang Utan (Pongo pygmaeus) sitting, holding two young. One is her own offspring, the other was rejected by its birth mother, and so this female has adopted it. Both young are 3 months old.Capt...

Danny Green / Polar bear (Ursus maritimus) female resting with cubs on glacier. Svalbard, Norway, July.

Danny Green / Polar bear (Ursus maritimus) female and cubs feeding on Whale carcass. Svalbard, Norway, July.

Danny Green / Polar bear (Ursus maritimus) and two cubs feeding on Whale carcass. Svalbard, Norway, July.

Danny Green / Polar bear (Ursus maritimus) and cubs, standing on sea ice. Svalbard, Norway, July.

Danny Green / Polar bear (Ursus maritimus) and cubs resting on sea ice. Svalbard, Norway, July.

Danny Green / Polar bear (Ursus maritimus) female and cubs, one cub walking up slope of ice in foreground. Svalbard, Norway, July.

Danny Green / Polar bear (Ursus maritimus) and cubs feeding on Whale carcass. Svalbard, Norway, July.

Danny Green / Polar bear (Ursus maritimus) and cubs feeding on Whale carcass, on iceberg. Svalbard, Norway, July 2018.

Danny Green / Polar bear (Ursus maritimus) female and cubs play fighting. Svalbard, Norway, March 2018.

Felis Images / Asiatic lion (Panthera leo persica), female and cubs in morning light, cub biting mother's leg. Gir National Park, Gujarat, India. Photo Phillip Ross/Felis Images

Mark Raycroft / Woodland Caribou (Rangifer tarandus caribou) mother nursing calf, Newfoundland, Canada

Fiona Rogers / Eastern Chimpanzee (Pan troglodytes schweinfurthii) five year old juvenile female, named Fadhila, playing with her three year old brother, named Fifty, Gombe National Park, Tanzania

Edwin Giesbers / Close-up of a litter of Wild boar (Sus scrofa) piglets sleeping on top of their mother, with another piglet joining, Germany, January. Captive.

Edwin Giesbers / Close-up of a litter of Wild boar (Sus scrofa) piglets sleeping on top of their mother, with another piglet joining, Germany, January. Captive.

Edwin Giesbers / Close-up of a litter of Wild boar (Sus scrofa) piglets sleeping on top of their mother, Germany, January. Captive.

Brian Bevan / Grey seal (Halichoerus grypus) pup trying to suckle, Norfolk, England, UK, January.

Frederique Olivier / Young Burchell's zebra (Equus burchellii) playing, biting and kicking its mother, Serengeti NP, Tanzania.

Thomas Marent / Saddle-back Tamarin (Saguinus fuscicollis) mother with young, Tambopata-Candamo Nature Reserve, Peru

Suzi Eszterhas / Proboscis Monkey (Nasalis larvatus) mother nursing four month old baby, Sabah, Borneo, Malaysia

Andy Rouse / Bengal tiger (Panthera tigris tigris) female 'T19 Krishna' carrying 2 month cub, Ranthambhore National Park, India.

Suzi Eszterhas / Capybara (Hydrochoerus hydrochaeris) mother nursing young, Pantanal, Brazil

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

David Pattyn / Little Grebe (Tachybaptus ruficollis) female sleeping with one of her 28 day chicks. The Netherlands, June.

Suzi Eszterhas / Ring-tailed Lemur (Lemur catta) mother and week-old twins, Berenty Private Reserve, Madagascar

Cyril Ruoso / Barbary Macaque (Macaca sylvanus) mother with infant reprimanding her older child, Morocco

Suzi Eszterhas / Mountain Gorilla (Gorilla gorilla beringei) mother holding five month old twin babies, Parc National des Volcans, Rwanda

Suzi Eszterhas / Mountain Gorilla (Gorilla gorilla beringei) mother holding five month old twin babies, Parc National des Volcans, Rwanda

Rob Jordan / 2020VISION / Merlin (Falco columbarius) female on perch with Meadow Pipit chick prey for its offspring. Sutherland, Scotland, UK, June. 2020VISION Book Plate.

Rob Jordan / 2020VISION / Merlin (Falco columbarius) female on perch with Meadow Pipit chick prey for its offspring. Sutherland, Scotland, June.

Rob Jordan / 2020VISION / Merlin (Falco columbarius) female on perch with Meadow Pipit chick prey for its offspring. Sutherland, Scotland, June.

Rob Jordan / 2020VISION / Merlin (Falco columbarius) female on perch with Meadow Pipit chick prey, legs just visible, for its offspring. Sutherland, Scotland, June.

Suzi Eszterhas / Sumatran Orangutan (Pongo abelii) female grabbing the hand of her offspring, aged 1.5 years, North Sumatra, Indonesia. Critically Endangered

Ann & Steve Toon / Roan antelope (Hippotragus equinus) with young offspring, Mlilwane nature reserve breeding programme, Swaziland, Southern Africa

Winfried Wisniewski / Cheetah (Acinonyx jubatus) mother with five cubs on a termite mound, Masai Mara National Reserve, Kenya

Suzi Eszterhas / Cheetah (Acinonyx jubatus) mother and eight week old cubs, Maasai Mara Reserve, Kenya

Mitsuaki Iwago / African Elephant (Loxodonta africana) mother and calf, Serengeti National Park, Tanzania

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

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

Yva Momatiuk & John Eastcott / Masai Giraffe (Giraffa tippelskirchi) mother nursing newborn, Masai Mara, Kenya

Mark Raycroft / Golden Retriever (Canis familiaris) portrait of mother and puppy resting on green grassy lawn

Mitsuaki Iwago / African Lion (Panthera leo) cub nuzzling sleeping mother, Serengeti National Park, Tanzania

Konrad Wothe / Black Rhinoceros (Diceros bicornis) mother and calf crossing savannah, Ngorongoro Crater, Tanzania

Mitsuaki Iwago / African Elephant (Loxodonta africana) calf playing with mother's tail, Masai Mara National Park, Kenya

Mitsuaki Iwago / African Lion (Panthera leo) mother with cub at dawn, Serengeti National Park, Tanzania

Mitsuaki Iwago / African Lion (Panthera leo) mother and cub at rest, Serengeti National Park, Tanzania

Mitsuaki Iwago / Blue Wildebeest (Connochaetes taurinus) mother giving birth, Serengeti

Mitsuaki Iwago / African Lion (Panthera leo) mother and sleeping cub, Serengeti National Park, Tanzania

Mitsuaki Iwago / African Lion (Panthera leo) mother and cub, Serengeti National Park, Tanzania

Mitsuaki Iwago / African Lion (Panthera leo) female and cubs drinking, Serengeti National Park, Tanzania

Mitsuaki Iwago / Burchell's Zebra (Equus burchellii) mother and foal, Botswana

Mitsuaki Iwago / Burchell's Zebra (Equus burchellii) mother and foal, Botswana

Gerry Ellis / African Elephant (Loxodonta africana) infant begging mother to nurse, Amboseli National Park, Kenya

Tim Fitzharris / African Elephant (Loxodonta africana) mother leading calf, Kenya

Mitsuaki Iwago / African Lion (Panthera leo) three month old cub sleeping on mother's leg, Ngorongoro Conservation Area, Tanzania

Mitsuaki Iwago / Hippopotamus (Hippopotamus amphibius) mother wallowing with her young, Kenya

Matthias Breiter / Grizzly Bear (Ursus arctos horribilis) adult female nursing her two yearling cubs on sedge flats, Katmai National Park, Alaska

Konrad Wothe / Timber Wolf (Canis lupus) mother with two pups begging for food at den entrance, Pine County, Minnesota

Sumio Harada / Red Squirrel (Tamiasciurus hudsonicus) mother nursing her 15 day old babies in nest, Rocky Mountains, North America

Thomas Mangelsen / Polar Bear (Ursus maritimus) mother resting with cub in snow, Churchill, Manitoba, Canada

Thomas Mangelsen / Polar Bear (Ursus maritimus) cub with paw over eyes, nestled in mothers' chest, Wapusk National Park, Manitoba, Canada

Yva Momatiuk & John Eastcott / Mustang (Equus caballus) mare and her foal flee danger in cloud of dust in the summer season, Wyoming

Yva Momatiuk & John Eastcott / Mustang (Equus caballus) palomino yearling filly and her spring foal brother grooming each other, Pryor Mountain Wild Horse Range, Montana

Yva Momatiuk & John Eastcott / Mustang (Equus caballus) mare and foal silhouetted against evening sky during summer, Montana

Claus Meyer / Scorpion tail ends in a stinger that protects the young carried on back, Caatinga ecosystem, Brazil

Sumio Harada / Red Squirrel (Tamiasciurus hudsonicus) mother nursing babies in nest, Rocky Mountains, North America

Konrad Wothe / Eurasian Lynx (Lynx lynx) pair sitting together in woods, back view, Bayerischer Wald National Park, Germany

Mitsuaki Iwago / African Elephant (Loxodonta africana) mother and calf walking together side by side, Kenya

Flip Nicklin / Sperm Whale (Physeter macrocephalus) mother and albino baby swimming, Portugal

Michio Hoshino / Grizzly Bear (Ursus arctos horribilis) mother and cub standing in green foliage, Alaska

Michio Hoshino / Grizzly Bear (Ursus arctos horribilis) mother and cub, Alaska

Flip Nicklin / Atlantic Spotted Dolphin (Stenella frontalis) group with unspotted calf, Bahamas

Jim Brandenburg / American Bison (Bison bison) mother with nursing calf, South Dakota

Mitsuaki Iwago / Labrador Retriever (Canis familiaris) mother resting with puppy

Mitsuaki Iwago / Koala (Phascolarctos cinereus) mother with young clinging to back, Australia

Mitsuaki Iwago / Red Kangaroo (Macropus rufus) mother grazing with joey in pouch, Australia

Tui De Roy / Galapagos Sea Lion (Zalophus wollebaeki) newborn pup nursing, Cape Douglas, Fernandina Island, Galapagos Islands, Ecuador

Mitsuaki Iwago / Golden Retriever (Canis familiaris) mother with three puppies, Japan

Michael Quinton / Trumpeter Swan (Cygnus buccinator) parent and squabbling day-old cygnets, North America

Mitsuaki Iwago / Airedale Terrier (Canis familiaris) mother and puppy, Japan

Mitsuaki Iwago / Domestic Horse (Equus caballus) and foal, Australia

Mitsuaki Iwago / Domestic Cat (Felis catus) with kittens, Japan

Mitsuaki Iwago / Red Kangaroo (Macropus rufus) mother hopping with young in pouch, Australia

ZSSD / African Elephant (Loxodonta africana) calf leaning on its mothers legs, native to Africa

ZSSD / African Hedgehog (Atelerix algirus) mother and baby, native to Africa

ZSSD / East African River Hippopotamus (Hippopotamus amphibius kiboko) mother and baby playing in water, native to Africa

ZSSD / East African River Hippopotamus (Hippopotamus amphibius kiboko) mother and baby underwater, native to Africa

Shin Yoshino / Koala (Phascolarctos cinereus) mothers and babies in tree, Australia

ZSSD / East African River Hippopotamus (Hippopotamus amphibius kiboko) mother and baby underwater, native to Africa

Mitsuaki Iwago / Cape Barren Goose (Cereopsis novaehollandiae) parent and goslings, Kangaroo Island, Australia

Mitsuaki Iwago / Koala (Phascolarctos cinereus) mother and young in tree, Australia

Mitsuaki Iwago / Red Kangaroo (Macropus rufus) joey inside mother's pouch, 130 days old, Australia

Mitsuaki Iwago / Red Kangaroo (Macropus rufus) newborn joey feeds while inside mother's pouch, 30 days old, Australia

Flip Nicklin / Bottlenose Whale (Hyperoodon ampullatus) cow and calf surfacing, Nova Scotia, Canada

Mitsuaki Iwago / African Elephant (Loxodonta africana) juvenile and calf, Serengeti National Park, Tanzania

Flip Nicklin / Humpback Whale (Megaptera novaeangliae) mother and calf, Hawaii