Stefan Christmann / Emperor penguin (Aptenodytes forsteri) pair in courtship, on sea ice. Atka Bay, Antarctica. May.

Jack Dykinga / Burrowing owl (Athene cunicularia), two huddled together. Marana, Pima County, Arizona, USA.

Cyril Ruoso / Golden monkey (Rhinopithecus roxellana) adult male and female hugging, Qinling Mountains, China.

Fiona Rogers / Southern plains grey langur / Hanuman langur (Semnopithecus dussumieri) infant aged a few weeks. Jodhpur, Rajasthan, India. March.

Anup Shah / Southern plains grey langur / Hanuman langur (Semnopithecus dussumieri) females hugging to reinforce rank. Jodhpur, Rajasthan, India. March.

Edwin Giesbers / Brown headed spider monkey (Ateles fusciceps) mother and baby, captive occurs in Central and South America.

Edwin Giesbers / Brown headed spider monkey (Ateles fusciceps) group resting together, captive occurs in Central and South America.

Anup Shah / Eastern chimpanzee (Pan troglodytes schweinfurtheii) young baby of adolescent female 'Golden' suckling. Gombe National Park, Tanzania.

Yukihiro Fukuda / Japanese macaque (Macaca fuscata fuscata) mother with rare white furred male baby, Jigokudani Valley, Nagano Prefecture, Japan. June.

Pascal Pittorino / Mediterranean tree frogs (Hyla meridionalis) mating on a branch of Quince tree (Cydonia oblonga) Var, Provence, France, April.

Aflo / Japanese macaque (Macaca fuscata) mother cuddling baby, Yamanouchi, Shimotakai District, Nagano Prefecture, Japan. June.

Suzi Eszterhas / Koala (Phascolarctos cinereus) mother with joey aged eight months, Queensland, Australia, captive.