A female hippopotamus named “Mali”, which means Jasmine, eats fruits arranged to look like a cake during her 50th birthday celebration at Dusit Zoo in Bangkok, Thailand September 23, 2016. (Photo by Chaiwat Subprasom/Reuters)

The provincial highest chimney collapses as it is demolished by explosives in Shenyang, Liaoning province, April 28, 2014. The 150-metre-high chimney used to be part of a local heating factory, according to local media. (Photo by Sheng Li/Reuters)

Seehund “Bruno” looks out of his transport box before making his way to the water on the beach of the island of Juist, Germany on August 14, 2013. Four young seals were released after six weeks of recovery at a rescue station in Norden-Norddeich. (Photo by Carmen Jaspersen/AFP Photo/DPA)

Green Bay Packers' Johnathan Calvin rides a bike to NFL football training camp on July 27, 2017, in Green Bay, Wis. (Photo by Morry Gash/AP Photo)

Indonesian residents look at the Mount Sinabung volcano as it spews volcanic ash near the Tiga Pancur village in Karo, North Sumatra on August 3, 2016. Volcanic eruptions in Indonesia in recent days have forced the closure of two airports and disrupted some flights to the holiday island of Bali, officials said August 3. Mount Sinabung, a volcano on the western island of Sumatra which has been rumbling for some time, also erupted violently on August 2, although its ash clouds did not disrupt any flights. (Photo by Y.T. Haryono/AFP Photo)

An activist takes a selfie during a protest ahead of the 2015 Paris Climate Conference, in Paris, Sunday, November 29, 2015. More than 140 world leaders are gathering around Paris for high-stakes climate talks that start Monday, and activists are holding marches and protests around the world to urge them to reach a strong agreement to slow global warming. (Photo by Christophe Ena/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)

Arctic wolves in their new enclosure in the wildlife park in Hanau, Germany, 10 February 2015. The pack is one of the park's main attractions, which specializes in local and European breeds. (Photo by Boris Roessler/EPA)