African migrants stranded in Costa Rica walk near garbage on the Inter-American highway at the border between Costa Rica and Nicaragua, in Penas Blancas, Costa Rica, September 8, 2016. (Photo by Juan Carlos Ulate/Reuters)

People sit near a fully loaded in Madama near the border with Lybia on January 1, 2015. French Defence Minister Jean-Yves Le Drian paid a surprise visit to northern Niger on January 1, to visit a base being built to combat the growing flow of weapons and jihadists from neighbouring Libya. Le Drian travelled from Chad to Madama, a desert outpost about 100 kilometres from Libya, where he saw in the New Year with troops at a French base. Madama is situated on the route used by jihadists and arms smugglers in southern Libya to reach northern Mali and Niger. (Photo by Dominique Faget/AFP Photo)

A child plays with a plastic badminton racket in the old quarters of Delhi, India, March 3, 2016. (Photo by Anindito Mukherjee/Reuters)

A sticker is seen at the Rocky Mountain Guns and Ammo store in Parker, Colorado July 24, 2012. The killing of 12 people at a midnight screening of the new Batman movie in the Denver suburb of Aurora may spark a fresh round of soul-searching on America's relationship with guns but few predict any real change in the law. (Photo by Shannon Stapleton/Reuters)

A man waits for Queen Beatrix's abdication ceremony outside the Royal Palace in Amsterdam April 30, 2013. The Netherlands is celebrating Queen's Day on Tuesday, which will also mark the abdication of Queen Beatrix and the investiture of her eldest son Willem-Alexander. (Photo by Paul Vreeker/Reuters)

Kashmiri residents are evacuated in a tractor from their flooded neighborhood in Srinagar, India, Sunday, September 7, 2014. (Photo by Dar Yasin/AP Photo)

A country music fan cools off in the wind on the second day of the Stagecoach country music festival in Indio, California April 26, 2014. (Photo by Mike Blake/Reuters)

“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)