Stefan Christmann / Emperor penguin (Aptenodytes forsteri), group of three males incubating, one with begging chick. Atka Bay, Antarctica. August.

Stefan Christmann / Emperor penguin (Aptenodytes forsteri) male feeding chick aged a few days. Atka Bay, Antarctica. August. Sequence 1/2.

Stefan Christmann / Emperor penguin (Aptenodytes forsteri) male feeding chick aged a few days. Atka Bay, Antarctica. August.

Stefan Christmann / Emperor penguin (Aptenodytes forsteri) egg hatching on father's feet. Atka Bay, Antarctica. August.

Christophe Courteau / Mountain gorilla (Gorilla beringei beringei), silverback and juvenile son. Volcanoes National Park. Rwanda.

Chien Lee / Spike-browed Frog (Sphenophryne cornuta) father transporting froglets, Digul River, West Papua, Indonesia

Chien Lee / Spike-browed Frog (Sphenophryne cornuta) father transporting froglets, Digul River, West Papua, Indonesia

Tui De Roy / Magellanic Penguin (Spheniscus magellanicus) parents and chicks along coast, Saunders Island, Falkland Islands

Tui De Roy / Magellanic Penguin (Spheniscus magellanicus) pair calling near chicks, Saunders Island, Falkland Islands

Michael Quinton / Dall's Sheep (Ovis dalli) ram, lamb, and ewe, Yukon Territory, Canada

Alain Ghignone/ BIA / Great Crested Grebe (Podiceps cristatus) pair feeding chick, Piedmont, Italy

Alan Murphy/ BIA / Gambel's Quail (Callipepla gambelii) male with chick, Arizona