Morley Read / Slow motion clip of a group of male Mallards (Anas platyrhynchos) competing violently to mate with a single female, Cornwall, England, UK, May 2018. (non-ex)

Alex Mustard / Yellowtail tang (Zebrasoma xanthurum) male and female turn belly to belly during spawning to ensure fertilization. Temple, Ras Umm Sid, Sharm El Sheikh, Sinai, Egypt. Red Sea. This action is very fast...

Anup Shah / Eastern Chimpanzee (Pan troglodytes schweinfurthii) fourteen year old sub-adult male, named Fundi, making submissive facial gesture, Gombe National Park, Tanzania

Martin Willis / Splendid Fairywren (Malurus splendens) female and male, Queensland, Australia

Martin Willis / Rainbow Lorikeet (Trichoglossus haematodus) pair preening during courtship, Magnetic Island, Queensland, Australia

Danny Green / Polar bear (Ursus maritimus), male and female approaching each other across snow covered rocky landscape. Svalbard, Norway, April 2019.

Danny Green / Polar bear (Ursus maritimus) male approaching female on snow covered hill top. Svalbard, Norway, April 2019.

Danny Green / Polar bear (Ursus maritimus) male approaching female in rocky area covered in snow. Svalbard, Norway, April 2019.

Danny Green / Polar bear (Ursus maritimus) male female pair looking upwards, snow covered hills in background. Svalbard, Norway, April 2018.

John Cancalosi / Sonoran desert toad (Incilius alvarius) pair mating, with trail of spawn in water. Arizona, USA.

David Tipling / Common European adder (Vipera berus) two males fighting over a female. Holt, North Norfolk, England, UK. April

David Tipling / Common European adder (Vipera berus) two males fighting over a female, Holt, North Norfolk, England, UK. April