Robin's nest with a brown-headed cowbird egg (© Edward Kinsman/Science Photo Library)

Japanese Tea Garden, Golden Gate Park, San Francisco, California, USA (© luisascanio/iStock/Getty Images)

Burchell's zebras, Rietvlei Nature Reserve, South Africa (© Richard Du Toit/Minden Pictures)

Mainau, Lake Constance, Germany (© Amazing Aerial Agency/Offset by Shutterstock)

Grey seal in Donna Nook, Lincolnshire, England (© Frederic Desmette/Minden Pictures)

The Great Pyramid of Cholula, Puebla, Mexico (© mauritius images GmbH/Alamy)

Thoseghar waterfalls in Maharashtra, India (© Sonali Kumar/iStock/Getty Images Plus)

Wetlands near Moosehead Lake in Maine, USA (© Aaron Black-Schmidt/Tandem Stills + Motion)

Black-tailed godwits, Netherlands (© Edward van Altena/Minden Pictures)

Sea otter mother and pup, Monterey Bay, California, USA (© Suzi Eszterhas/Minden Pictures)

Tulip field in Miesbach, Bavaria, Germany (© Rüdiger Hess/geo-select FotoArt)

Grinnell Lake, Glacier National Park, Montana, USA (© Pung/Shutterstock)

A view across the River Shannon in Limerick, County Limerick, Ireland (© Piotr Machowczyk/Shutterstock)

Shikisai no Oka flower gardens in Biei, Japan (© Tanya Jones/Shutterstock)

Buttermere, Lake District, England (© Stewart Smith/Alamy)

Telescopes and star trails at Paranal Observatory, Atacama Desert, Chile (© Matteo Omied/Alamy)

El Peñón de Guatapé, Guatapé, Antioquia, Colombia (© Amazing Aerial Agency/Offset by Shutterstock)

Ålesund, Norway (© AWL Images/Offset by Shutterstock)

Great hornbill in West Bengal, India (© Debapratim Saha/Minden Pictures)

Banff National Park, Alberta, Canada (© Pgiam/Getty Images)

Hartland Point Lighthouse, Devon, England (© Adam Burton/Alamy Stock Photo)

Whooping cranes, South Dakota, USA (© Gerrit Vyn/Minden Pictures)

Tossa de Mar, Catalonia, Spain (© dleiva/Alamy)

The Rose Main Reading Room, New York Public Library, USA (© Sascha Kilmer/Getty Images)

The Infinite Bridge, Aarhus, Denmark (© Kosmaj/Shutterstock)

Sperm whale off the coast of Roseau, Dominica, in the Caribbean Sea (© Tony Wu/Minden Pictures)

The total lunar eclipse of 4 April 2015, Monument Valley, Utah, USA (© Alan Dyer/Alamy)

View from Varandha Ghat in the Western Ghats, Maharashtra, India (© AmitRane1975/iStock/Getty Images Plus)

Alley with red walls and bamboo grove in Wuhou Temple, Chengdu, Sichuan province, China (© Eastimages/Getty Images)

California sea lion in a forest of giant kelp near the Channel Islands of California, USA (© Nature Picture Library/Alamy)

Waterfall at Pöllat Gorge near Neuschwanstein Castle, Bavaria, Germany (© Gary Whitton/Alamy)