“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)

Elephants spray tourists with water in celebration of the Songkran water festival in Thailand's Ayutthaya province, about 80 km (50 miles) north of Bangkok, April 9, 2014. (Photo by Rungroj Yongrit/EFE)

“Aurora Hunters”. Photographers taking part in a photography tour on the Lofoten Islands in Norway, pull over on the side of the road to take a photo of their first ever Aurora Borealis after spotting it from their tour bus. Photo location: Rystad, Lofoten Islands, Norway. (Photo and caption by Mark Gee/National Geographic Photo Contest)

Cyril Despres of France tries to get his Peugeot out of the sand as co-pilot David Castera pushes the car during the 10th stage of the Dakar Rally 2016 near Fiambala, Argentina, January 13, 2016. (Photo by Marcos Brindicci/Reuters)

People watch police destroy confiscated illegal firecrackers in Shenyang, Liaoning province, China, January 29, 2016. (Photo by Reuters/Stringer)

A TV journalist reports next to a life-size cutout of Pope Francis outside the Catholic Nunciature before the pontiff arrives in Mexico City, Friday, February 12, 2016. Pope Francis is arriving in Mexico on Friday for a week-long visit. (Photo by Christian Palma/AP Photo)

A child blowing confetti from her hands during a Carnival parade in Cyprus' coastal city of Limassol, Sunday, March 13, 2016. Limassol's long-established parade is Cyprus' biggest and most famous, drawing revelers from across the east Mediterranean island. This year's parade drew huge crowds as people sought lighthearted reprieve from the bailed-out country's recession. The parade marks the start of the 40-day fasting period of Lent in the run-up to the Orthodox Christian Easter. (Photo by Petros Karadjias/AP Photo)

People take part in the Classic Ride Rally in downtown Valencia, eastern Spain, 23 November 2014. Some hundred people on classic bikes from the 20's to the 70's participated in the rally. (Photo by Kai Foersterling/EPA)