A dog catches a wave during the Surf City Surf Dog Contest in Huntington Beach, California September 27, 2015. (Photo by Lucy Nicholson/Reuters)

Three Palestinian women sit on a beachfront as a wave comes rushing by in Gaza City on November 17, 2016. (Photo by Mohammed Abed/AFP Photo)

Hillary Clinton waves to a selfie-taking crowd at a recent campaign event in Orlando, Florida on September 26, 2016. (Photo by Barbara Kinney/Hillary for America)

“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)

Venezuela's food shortages, inflation and crumbling medical sector have become such a source of anguish that a growing number of young women are reluctantly opting for sterilizations rather than face the hardship of pregnancy and child-rearing. Traditional contraceptives like condoms or birth control pills have virtually vanished from store shelves, pushing women towards the hard-to-reverse surgery. While no recent national statistics on sterilizations are available, doctors and health workers say demand for the procedure is growing. (Photo by Carlos Garcia Rawlins/Reuters)

A man walks on the Cobb as storm waves break behind on December 13, 2011 in Lyme Regis, England. (Photo by Matt Cardy/Getty Images)

An Aymara woman with a sheep waves to the crowd during a Christmas parade in La Paz, Bolivia December 12, 2015. (Photo by David Mercado/Reuters)

A photographer could bear-ly believe his eyes when a bear started waving at him. The friendly animal wandered to the front of his enclosure before sitting back in full view of zoo guests. He then lifts his powerful paw and excitedly waves in an almost human-like way at his new audience. The hilarious encounter was captured by keen photographer Andrey Slepnev, 31, while on a trip to Madrid Zoo, Spain on March 24, 2016. (Photo by Andrey Slepnev/Caters News)