Tui De Roy / Short tailed albatross (Phoebastria albatrus) subadults courting, one with fish-hook and monofilament line embedded in throat. Tsubamezaki, Torishima Island, Japan. December.

Tony Heald / African lion (Panthera leo) three subadults resting on the road, one snarling, Central Kalahari Game Reserve, Botswana

Anup Shah / African lion (Panthera leo) young playing in water, Masai Mara National Reserve, Kenya, September

Florian Möllers / Golden snub-nosed monkey (Rhinopithecus roxellana qinlingensis) females, subadults and infants socialising in tree, Zhouzi Nature Reserve, Qinling mountains, Shaanxi, China. April 2006

Doug Perrine / Spiny lobster migration march from juvenile to adult habitat {Panulirus argus} Bahamas, Caribbean (Non-ex).

Karine Aigner / Bengal tiger (Panthera tigris tigris), two subadults walking across the savannah. Ranthambore National Park, Rajasthan, India. 2018.

Tui De Roy / Short tailed albatross (Phoebastria albatrus) subadults courting, one with fish-hook and monofilament line embedded in throat. Tsubamezaki, Torishima Island, Japan. December.

Tui De Roy / Short tailed albatross (Phoebastria albatrus) subadults courting, one with fish-hook and monofilament line embedded in throat. Tsubamezaki, Torishima Island, Japan. December.

Ingo Arndt / Antarctic fur seal (Arctocephalus gazella) playfighting, King Edward Point, South Georgia Island, February

Wim van den Heever / Steller's sea eagle (Haliaeetus pelagicus) two subadults fighting in midair, Shiretoko Peninsula, Hokkaido, Japan

Axel Gomille / Sloth bear (Melursus ursinus) old male watching play-fighting subadults, Karnatka, India.

Axel Gomille / Sloth bear (Melursus ursinus) old male interacting with play-fighting subadults, Karnatka, India.

Richard Du Toit / Cheetah (Acinonyx jubatus) subadults playing Kgalagadi Transfrontier Park, Northern Cape Province, South Africa, February.

Tui De Roy / Short-tailed Albatross (Phoebastria albatrus) subadults courting, Tsubamezaki, Torishima Island, Japan

Tui De Roy / Short-tailed Albatross (Phoebastria albatrus) pair of subadults courting, Torishima Island, Japan. Sequence 7 of 8

Tui De Roy / Short-tailed Albatross (Phoebastria albatrus) pair of subadults courting, Torishima Island, Japan. Sequence 6 of 8

Tui De Roy / Short-tailed Albatross (Phoebastria albatrus) pair of subadults courting, Torishima Island, Japan. Sequence 5 of 8

Tui De Roy / Short-tailed Albatross (Phoebastria albatrus) pair of subadults courting, Torishima Island, Japan. Sequence 4 of 8

Tui De Roy / Short-tailed Albatross (Phoebastria albatrus) pair of subadults courting, Torishima Island, Japan. Sequence 2 of 8

Tui De Roy / Short-tailed Albatross (Phoebastria albatrus) pair of subadults courting, Torishima Island, Japan. Sequence 1 of 8

Tui De Roy / Short-tailed Albatross (Phoebastria albatrus) pair of subadults courting, Torishima Island, Japan. Sequence 8 of 8

Steven Kazlowski / Pair of polar bear (Ursus maritimus) subadults engage in play, off Bernard Spit, North Slope of the Brooks Range, Beaufort Sea, Alaska, October.

Steven Kazlowski / Pair of polar bear (Ursus maritimus) subadults engage in play, off Bernard Spit, North Slope of the Brooks Range, Beaufort Sea, Alaska, October.

Steven Kazlowski / Pair of polar bear (Ursus maritimus) subadults engage in play, off Bernard Spit, North Slope of the Brooks Range, Arctic National Wildlife Refuge, Beaufort Sea, Alaska, October.

Steven Kazlowski / Pair of polar bear (Ursus maritimus) subadults engage in play, off Bernard Spit, North Slope of the Brooks Range, Beaufort Sea, Alaska, October.

Florian Möllers / River otter (Lutra lutra), two subadults playing on frozen pond, captive in enclosure of the Bavarian Forest National Park, Germany, February

Anup Shah / Celebes / Black crested macaque (Macaca nigra) sub-adult male resting against a small tree, Tangkoko National Park, Sulawesi, Indonesia.

Anup Shah / Celebes / Black crested macaque (Macaca nigra) juvenile attempting to mate with a sub-adult male, Tangkoko National Park, Sulawesi, Indonesia.

Andrew Parkinson / Bengal Tigers (Panthera tigris), two subadults, approximately 17-19 months old, leaping, playing and fighting. Endangered. Bandhavgarh National Park, India. Non-ex. Sequence 1 of 2.

Anup Shah / Western lowland gorilla (Gorilla gorilla gorilla) sub-adult male 'Kunga' aged 13 years standing in Bai Hokou, Dzanga Sangha Special Dense Forest Reserve, Central African Republic. December 2011.

Anup Shah / African lions (Panthera leo) two young lions play fighting in water, Masai Mara National Reserve, Kenya, September

Anup Shah / African lions (Panthera leo) adolescent males resting together, Masai Mara National Reserve, Kenya, September

Anup Shah / African lions (Panthera leo) sub-adult males making advances on lioness, Masai Mara National Reserve, Kenya, September

Andrew Parkinson / Red grouse (Lagopus lagopus scoticus) subadults forage together in heather, Yorkshire Dales National Park, Yorkshire, UK, August.

Anup Shah / Eastern White bearded wildebeest herd running (Connochates taurinus albojubatus), Masai Mara National Reserve, Kenya

Anup Shah / Lion adolescents play fighting (Panthera leo), Masai Mara National Reserve, Kenya, April

Anup Shah / Olive baboon (Papio cynocephalus anubis) juveniles playing, Masai Mara National Reserve, Kenya, February

Markus Varesvuo / Bearded vulture (Gypaetus barbatus) portrait, subadult, Spain, November

Steven Kazlowski / Two unreleated Polar bear (Ursus maritimus) subadults fighting on the carcass of a dead Fin whale (Balaenoptera physalus) floating along the Svalbard coast, Norway

Yva Momatiuk & John Eastcott / King Penguin (Aptenodytes patagonicus) and Antarctic Fur Seal (Arctocephalus gazella) pups and subadults in sea surf and on beach, fall morning, Right Whale Bay, South Georgia Island, Southern Ocean,...

Yva Momatiuk & John Eastcott / King Penguin (Aptenodytes patagonicus) and Antarctic Fur Seal (Arctocephalus gazella) pups and subadults in sea surf and on beach, fall morning, Right Whale Bay, South Georgia Island, Southern Ocean,...

Yva Momatiuk & John Eastcott / King Penguin (Aptenodytes patagonicus) and Antarctic Fur Seal (Arctocephalus gazella) pups and subadults in surf and on beach, fall morning, Right Whale Bay, South Georgia Island, Southern Ocean, Anta...

Doug Perrine / Juvenile Atlantic spotted dolphins {Stenella frontalis} spots develop later, Bahamas (Non-ex).

Doug Perrine / Atlantic spotted dolphins juveniles without spots {Stenella frontalis} Bahamas (Non-ex).

Richard Du Toit / Lion subadults playing {Panthera leo} Okavango delta, Botswana

Tui De Roy / Short-tailed Albatross (Phoebastria albatrus) pair of subadults courting, Torishima Island, Japan. Sequence 3 of 8