A horse-drawn cart passing through a section cut out of the base of a giant sequoia tree in the Mariposa groves of Yosemite Park, California. (Photo by Carleton E Watkins/Getty Images). 1870

Zhang Ze of China in action during his Oceania zone group1 match against Bernard Tomic of Australia of the 2011 Davis Cup on July 8, 2011 in Beijing, China. (Photo by Lintao Zhang/Getty Images)

Indian wrestlers Rashid Anwar (left) and Ajaib Singh in a training bout at Lane's Club in Baker Street London before the Empire Games, 19th July 1934. (Photo by Keystone/Hulton Archive/Getty Images)

Two stags fight in a wildlife park in Aurach near Kitzbuehel, in the Austrian province of Tyrol. (Photo by Kerstin Joensson/Associated Press)

“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)

Artwork by Ruth Bellotti & Steve Rosewell called “Soldier Scale 1:1” is seen at the 2008 Sculpture by the Sea launch at Mark's Park, Bondi on October 15, 2008 in Sydney, Australia. (Photo by Gaye Gerard/Getty Images)

A baby Chimpanzee plays in its enclosure at Taronga Zoo July 14, 2006 in Sydney, Australia. (Photo by Ian Waldie/Getty Images)

The moon shines through trees at a United Nations displacement camp at dusk on March 14, 2011 in Ras Jdir, Tunisia. (Photo by Dan Kitwood/Getty Images)