“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)

Olivia Love-Hatlestad of Grayslake, IL., stands during the second day of the Democratic National Convention at the Wells Fargo Center, July 26, 2016 in Philadelphia, Pennsylvania. An estimated 50,000 people are expected in Philadelphia, including hundreds of protesters and members of the media. The four-day Democratic National Convention kicked off July 25. (Photo by Drew Angerer/Getty Images)

A Nepalese devotee prepares for a religious mask performance during the Seekaali Festival in Khokna village, near Kathmandu, Nepal, 07 October 2016. During the 300-year-old Seekali festival, elderly ethnic Newari devotees wear masks of 14 various goddesses including Lord Ganesha, Lord Shiva, Lord Laxmi, Lord Brahma and Lord Bishnu. The Khokna people celebrate the Seekaali festival as an alternative of the Dashain festival which is biggest festival of Nepalese Hindus that celebrates the victory of the gods over demons. (Photo by Narendra Shrestha/EPA)

A visitor jumps for a photograph on the world's highest and longest glass-bottomed bridge above a valley in Zhangjiajie in China's Hunan Province on August 21, 2016. The bridge, which opened to the public on a trial basis on Saturday, spans 430 meters (1,410 feet) and rises about 300 meters (984 feet) above a valley in a scenic zone, making it the world's highest and longest glass-bottomed bridge according to Chinese state media. (Photo by Fred Dufour/AFP Photo)

Base jumper Denis Odintsov from Russian leaps from the 300-meters Open Deck of the Malaysia's landmark Kuala Lumpur Tower during the International Tower Jump in Kuala Lumpur on September 27, 2013. Some 103 professional base jumpers from 20 countries are taking part in the annual event. (Photo by Mohd Rasfan/AFP Photo)

Two dancers pass each other as they compete in a heat during the All Scotland Championships in Irish Dancing at the Royal Concert Hall in Glasgow, Scotland. The championships attract over 2000 dancers from more than 300 dance schools, from countires such as North America, South Africa, Australia and Russia. (Photo by David Moir/Reuters)

Armin Bielefeldt of the U.S. poses with his beard art work before the Beard World Championship 2013 in Leinfelden-Echterdingen near Stuttgart November 2, 2013. Bielefeldt needs more than 6 hours for his art work. More than 300 people from around the world compete in different moustache and beard categories. (Photo by Michaela Rehle/Reuters)