Tourists sit around a bonfire on the Makgadikgadi salt pan in Botswana. (Photo by Yang Mengxi/Xinhua News Agency/Barcroft Media)

A gallery assistant poses by a sculpture entitled “Dark Place” by Australian artist Ron Mueck displayed at Thaddaeus Ropac gallery in London, Britain, October 11, 2021. The exhibition dedicated to Ron Mueck will open to the public from Oct. 12 to Nov. 13 ahead of Frieze Week. (Photo by Matthew Childs/Reuters)

An aerial view of people visiting the roaring Hukou Waterfall on the Yellow River on August 11, 2025 in Yan'an, Shaanxi Province of China. Hukou waterfall is witnessing an increasing water flow lately. (Photo by Liu Yijiang/VCG via Getty Images)

A picture taken with a drone shows a huge work of art created with various flowers and flowering plants in Jacobsdorf, Germany, 29 July 2024. Artist Michael Uy has transformed a piece of fallow land into an insect paradise for bees, bumblebees and butterflies. Using plants, the artist has planted and sown oversized images in the shape of a shell and a winding path of life on a large meadow in Jacobsdorf. (Photo by Hannibal Hanschke/EPA/EFE)

Ngorongoro Crater (Tanzania). At 610m deep and 260 sq km, this is the largest unflooded caldera in the world. A blue-green vision from above it's a haven for engangered wildlife and Maasai livestock. The crater was formed three million years ago when a giant volcano, which could have been as high as Kilimanjaro, exploded and collapsed. The caldera formed the concentric fractures in the crust cracked down to a magma reservoir deep underground. (Photo by John Bryant/Getty Images)

A Humboldt penguin stands on weighing scales whilst being photographed by members of the press during a photocall at the annual weigh-in at London Zoo in London, Britain, 24 August 2016. Every animal that is in the zoo is weighed and measured and the statistics recorded so the data can be shared with zoos across the world. (Photo by Hannah McKay/EPA)

Miss Colombia Ariadna Gutierrez, right, and Miss Philippines Pia Alonzo Wurtzbach wait for the announcer to name the new Miss Universe at the Miss Universe pageant on Sunday, December 20, 2015, in Las Vegas. Gutierrez was incorrectly crowned before Wurtzbach was named Miss Universe. (Photo by John Locher/AP Photo)

“Cassowaries are large, flightless birds related to emus and (more distantly) to ostriches, rheas, and kiwis”, writes Olivia Judson in the September issue of National Geographic magazine. How large? People-size: Adult males stand well over five foot five and top 110 pounds. Females are even taller, and can weigh more than 160 pounds. Dangerous when roused, they’re shy and peaceable when left alone. But even birds this big and tough are prey to habitat loss. The dense New Guinea and Australia rain forests where they live have dwindled. Today cassowaries might number 1,500 to 2,000. And because they help shape those same forests – by moving seeds from one place to another – “if they vanish”, Judson writes, “the structure of the forest would gradually change” too. (Photo by Christian Ziegler/National Geographic)