ZSSD / Rothschild Giraffe (Giraffa camelopardalis rothschildi) mother and calf nuzzling, native to Africa

Fiona Rogers / Bornean Orang-utan (Pongo pygmaeus wurmbii) female 'Siswi's' hand holding foot close-up. Camp Leakey, Tanjung Puting National Park, Central Kalimantan, Borneo, Indonesia, June 2010. Rehabilitated and...

Yva Momatiuk & John Eastcott / African Lion (Panthera leo) courting male and female, Masai Mara National Reserve, Kenya

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

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

Winfried Wisniewski / African Lion (Panthera leo), African Lioness carrying cub, Masai Mara National Reserve, Kenya

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

Richard Du Toit / Cheetah (Acinonyx jubatus) adult female laying in the grass with her three month old cubs, summer, Phinda Game Reserve, South Africa

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

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

Gerry Ellis / Dromedary (Camelus dromedarius) camel mother with two day old baby, Oasis Dakhia, Sahara, Egypt

Gerry Ellis / African Elephant (Loxodonta africana) mother and baby, Amboseli National Park, Kenya

Mitsuaki Iwago / African Lion (Panthera leo) females grooming, Serengeti National Park, Tanzania

Katherine Feng / Giant Panda (Ailuropoda melanoleuca) Gongzhu is successfully re-introduced to one of her nine week old twin cubs which she initially rejected, China Conservation and Research Center for the Giant Pand...

Mitsuaki Iwago / Basenji (Canis familiaris) two puppies nose to nose, Japan

Heidi & Hans-Juergen Koch / Domestic Cattle (Bos taurus) mother and calf nuzzling, Germany

Konrad Wothe / Orangutan (Pongo pygmaeus) orphans embracing, Borneo, Malaysia

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

Yva Momatiuk & John Eastcott / Mustang (Equus caballus) young bachelor stallions sniffing each other, Pryor Mountain Wild Horse Range, Montana

Gerry Ellis / Koala (Phascolarctos cinereus) mother and joey, three month old, Australia

Katherine Feng / Giant Panda (Ailuropoda melanoleuca) mother and two week old infant, Wolong Nature Reserve, China

Katherine Feng / Giant Panda (Ailuropoda melanoleuca) mother and her cub at the China Conservation and Research Center for the Giant Panda, Wolong Nature Reserve, China

Konrad Wothe / Bonobo (Pan paniscus) mother and baby interacting, native to Africa

Konrad Wothe / Eurasian Lynx (Lynx lynx) pair touching noses in snow, Bayerischer Wald National Park, Germany

Gerry Ellis / Koala (Phascolarctos cinereus) mother and three month old joey in tree, Australia

Gerry Ellis / Koala (Phascolarctos cinereus) mother and joey, three month old, Australia

Tui De Roy / Waved Albatross (Phoebastria irrorata) pair bonding in flowering tribulus field during rains, Punta Cevallos, Espanola Island, Galapagos Islands, Ecuador

Michio Hoshino / Galapagos Sea Lion (Zalophus wollebaeki) pair nuzzling, Galapagos Islands, Ecuador

Michio Hoshino / Galapagos Sea Lion (Zalophus wollebaeki) pair resting on beach, Galapagos Islands, Ecuador

Tui De Roy / Emperor Penguin (Aptenodytes forsteri) parents greeting chick, Atka Bay, Princess Martha Coast, Weddell Sea, Antarctica

ZSSD / Red River Hog (Potamochoerus porcus) pair standing face to face, a highly social bush pig, native to Africa

Tui De Roy / Hooker's Sea Lion (Phocarctos hookeri) cow bonding with young pup, Enderby Island, Auckland Islands, New Zealand

Kevin Schafer / Red and Green Macaw (Ara chloroptera) pair courting, Buraco das Araras, Mato Grosso do Sul, Pantanal, Brazil

Tui De Roy / African Elephant (Loxodonta africana) juvenile and calf, Ol Pejeta Conservancy, Kenya

Ingo Arndt / King Penguin (Aptenodytes patagonicus) adjusting egg balanced on its feet, King Edward Point, South Georgia Island

Thomas Marent / Sumatran Orangutan (Pongo abelii) mother kissing young, Gunung Leuser National Park, northern Sumatra, Indonesia

Thomas Marent / Orangutan (Pongo pygmaeus) female cleaning young, Camp Leakey, Tanjung Puting National Park, Borneo, Indonesia

Thomas Marent / Orangutan (Pongo pygmaeus) mother's and baby's hands, Camp Leakey, Tanjung Puting National Park, Borneo, Indonesia

Thomas Marent / Orangutan (Pongo pygmaeus) mother holding young, Camp Leakey, Tanjung Puting National Park, Borneo, Indonesia

Mitsuaki Iwago / Japanese Macaque (Macaca fuscata) mother gently touching young, Jigokudani, Japan

Mitsuaki Iwago / Orangutan (Pongo pygmaeus) mother holding young, Borneo, Malaysia

Mitsuaki Iwago / Orangutan (Pongo pygmaeus) mother holding young, Borneo, Malaysia

Mitsuaki Iwago / Orangutan (Pongo pygmaeus) babies interacting, Borneo, Malaysia

Mitsuaki Iwago / Orangutan (Pongo pygmaeus) holding human hand, Borneo, Malaysia

Mitsuaki Iwago / Orangutan (Pongo pygmaeus) mother and young, Borneo, Malaysia

Suzi Eszterhas / Northern Elephant Seal (Mirounga angustirostris) mother with two week old pup, San Benito Island, Baja California, Mexico

Jan Vermeer / Emperor Penguin (Aptenodytes forsteri) pair courting, Snow Hill Island, Antarctica

Jan Vermeer / Emperor Penguin (Aptenodytes forsteri) parent with chick, Snow Hill Island, Antarctica

Suzi Eszterhas / Grizzly Bear (Ursus arctos horribilis) pair courting, Katmai National Park, Alaska

Suzi Eszterhas / Grizzly Bear (Ursus arctos horribilis) pair courting, Katmai National Park, Alaska

Michael Quinton / Red-throated Loon (Gavia stellata) with day old chick on nest, Alaska

Konrad Wothe / Royal Penguin (Eudyptes schlegeli) pair, Macquarie Island, Australia

ZSSD / Rothschild Giraffe (Giraffa camelopardalis rothschildi) mother nuzzling calf, native to Africa

ZSSD / Sun-tailed Guenon (Cercopithecus solatus) mother holding baby, threatened, native to Gabon

Konrad Wothe / Chimpanzee (Pan troglodytes) mother hugging infant, endangered, Africa

Suzi Eszterhas / Grizzly Bear (Ursus arctos horribilis) sow and 4-6 months-old cub, Katmai National Park, Alaska

Konrad Wothe / Donkey (Equus asinus) adult with foal, Bavaria, Germany

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

Flip de Nooyer / Mute Swan (Cygnus olor) courting pair on lake, Europe

Flip de Nooyer / Sandwich Tern (Thalasseus sandvicensis) parent with chick tucked safely under its wing, Europe

Flip de Nooyer / Sandwich Tern (Thalasseus sandvicensis) parent with chick tucked safely under its wing, Europe

Richard Du Toit / African Elephant (Loxodonta africana) two interacting with each other at water hole, Etosha National Park, Namibia

Richard Du Toit / African Lion (Panthera leo) two playful, resting females, Okavango Delta, Botswana

Tui De Roy / Erect-crested Penguin (Eudyptes sciateri) pair allopreening, Antipodes Island, New Zealand

Tui De Roy / Salvin's Albatross (Thalassarche salvini) pair bonding at nest site, Proclamation Island, Bounty Islands, New Zealand

Gerry Ellis / African Elephant (Loxodonta africana) keeper, Julius, shares a tender moment with Kinna, a young orphan, David Sheldrick Wildlife Trust, Tsavo East National Park, Kenya

Yva Momatiuk & John Eastcott / Cheetah (Acinonyx jubatus) adult female with cub after making a kill and letting cubs eat, she rests with one cub snuggled near, Masai Mara National Reserve, Kenya

Thomas Mangelsen / African Elephant (Loxodonta africana) group and calf, Etosha National Park, Namibia

Sumio Harada / Elk (Cervus elaphus) mother with calf, Rocky Mountains, North America

Heidi & Hans-Juergen Koch / Domestic Cattle (Bos taurus) mother and calf nuzzling, Germany

Heidi & Hans-Juergen Koch / Domestic Cattle (Bos taurus) mother and calf nuzzling, Germany

Sumio Harada / Mountain Goat (Oreamnos americanus) mother and kid, Glacier National Park, Montana

Katherine Feng / Giant Panda (Ailuropoda melanoleuca) Xi Xi with her 32 day old cub, China Conservation and Research Center for the Giant Panda, Wolong Nature Reserve, China

Katherine Feng / Giant Panda (Ailuropoda melanoleuca) Xi Xi with her 32 day old cub, China Conservation and Research Center for the Giant Panda, Wolong Nature Reserve, China

Katherine Feng / Giant Panda (Ailuropoda melanoleuca) Xi Xi with her 32 day old cub, China Conservation and Research Center for the Giant Panda, Wolong Nature Reserve, China

Katherine Feng / Giant Panda (Ailuropoda melanoleuca) Gongzhu is successfully re-introduced to one of her nine week old twin cubs which she initially rejected, China Conservation and Research Center for the Giant Pand...

Katherine Feng / Giant Panda (Ailuropoda melanoleuca) Xi Xi with her 32 day old cub, China Conservation and Research Center for the Giant Panda, Wolong Nature Reserve, China

Katherine Feng / Giant Panda (Ailuropoda melanoleuca) Xi Xi with her 32 day old cub, China Conservation and Research Center for the Giant Panda, Wolong Nature Reserve, China

Katherine Feng / Giant Panda (Ailuropoda melanoleuca) Xi Xi with her 32 day old cub, China Conservation and Research Center for the Giant Panda, Wolong Nature Reserve, China

Katherine Feng / Giant Panda (Ailuropoda melanoleuca) Xi Xi with her 32 day old cub, China Conservation and Research Center for the Giant Panda, Wolong Nature Reserve, China

Katherine Feng / Giant Panda (Ailuropoda melanoleuca) Xi Xi with her 32 day old cub, China Conservation and Research Center for the Giant Panda, Wolong Nature Reserve, China

Katherine Feng / Giant Panda (Ailuropoda melanoleuca) Xi Xi with her 32 day old cub, China Conservation and Research Center for the Giant Panda, Wolong Nature Reserve, China

Katherine Feng / Giant Panda (Ailuropoda melanoleuca) Xi Xi with her 32 day old cub, China Conservation and Research Center for the Giant Panda, Wolong Nature Reserve, China

Katherine Feng / Giant Panda (Ailuropoda melanoleuca) Xi Xi with her 32 day old cub, China Conservation and Research Center for the Giant Panda, Wolong Nature Reserve, China

Thomas Mangelsen / Polar Bear (Ursus maritimus) mother and cub resting on ice field, Churchill, Manitoba, Canada

Yva Momatiuk & John Eastcott / Timber Wolf (Canis lupus) female licking male signaling submission, Grizzly Discovery Center, Montana

Yva Momatiuk & John Eastcott / Mustang (Equus caballus) young bachelor stallions grooming each other, Pryor Mountain Wild Horse Range, Montana

Katherine Feng / Giant Panda (Ailuropoda melanoleuca) cub with caretaker at the China Conservation and Research Center for the Giant Panda, Wolong Nature Reserve, China

Tim Fitzharris / Greater Flamingo (Phoenicopterus ruber) mother and begging chick, Caribbean

Katherine Feng / Giant Panda (Ailuropoda melanoleuca) Xi Xi with her 32 day old cub, China Conservation and Research Center for the Giant Panda, Wolong Nature Reserve, China

Konrad Wothe / Orangutan (Pongo pygmaeus) orphan in cage holding hand of attendant, Borneo, Malaysia

Michael & Patricia Fogden / Brown-throated Three-toed Sloth (Bradypus variegatus) female in rainforest, Panama

Michael & Patricia Fogden / Hoffmann's Two-toed Sloth (Choloepus hoffmanni) sleeping baby, cloud forest ecosystem, Costa Rica

Konrad Wothe / Mute Swan (Cygnus olor) affectionate pair after mating, Germany

Gerry Ellis / Koala (Phascolarctos cinereus) mother with joey, Australia