“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)

Tsetse, six-year-old daughter of Dukha herder Erdenebat Chuluu, sits among her family's reindeer in a forest near the village of Tsagaannuur, Khovsgol aimag, Mongolia, April 21, 2018. Nyamaa is an ethnic Darkhad, herders of northern Mongolia who have historically inhabited the steppe that borders the Taiga forests. (Photo by Thomas Peter/Reuters)

A spotted owlet appears to be playing peek-a-boo near Rancharda Lake in Ahmedabad, India on February 9, 2016. The species is common across the Indian subcontinent. (Photo by Caters News Agency)

British tourists snap a cheeky selfie with a monkey at the Ubud Monkey Forest in Bali, Indonesia, August 4, 2015. George Benton, 22, from Paignton, Devon was visiting the Sacred Monkey Forest Sanctuary in Ubud, Bali whilst traveling with his girlfriend Chloe when the couple snapped a surprise shot with Balinese long-tailed monkey using a “selfie stick”. “We couldn't believe our luck when we looked back at the photos, he looked straight into the camera!” said George, who went on to reward the cheeky chap with a banana for giving the couple such a memorable photo. (Photo by George Benton/Splash News)

Participants lay down on a street covered by coloured powder during the annual Bangkok Color Run in Bangkok, Thailand April 1, 2017. (Photo by Athit Perawongmetha/Reuters)

A girl watches as Saen Dao, an eight-year-old female asian elephant, and her mahout perform underwater during a show at the Khao Kheow Open Zoo in Chonburi south of Bangkok on June 1, 2017. (Photo by Roberto Schmidt/AFP Photo)

Model Bella Hadid falls as she walks the runway at the Michael Kors Spring 2017 Runway Show duing New York Fasion Week at Spring Studios on September 14, 2016 in New York City. (Photo by Rex Features)

This picture taken on October 20, 2016 shows students practising wushu at the Tagou martial arts school in Dengfeng. China is investing hugely in football training and has vowed to have 50 million school- age players by 2020, as the ruling Communist party eyes “football superpower” status by 2050. (Photo by Nicolas Asfouri/AFP Photo)