In this undated photo made available by journal Nature on January 15, 2014, a northern bald ibis (Geronticus eremita) flies in Tuscany, Italy. A new study released Wednesday, January 15, 2014 says the birds choreograph the flapping of their wings, getting a boost from an updraft of air in the wake of the flapping wings by flying behind the first bird and off to the side. When a flock of birds take advantage of these aerodynamics, they form a V. (Photo by Markus Unsöld/AP Photo)

Ukrainian state emblem is seen on a gun's holster as soldiers guard naval base in the village of Novoozernoye, some 91 km west of Crimean capital Simferopol, Ukraine, on Monday, March 3, 2014. Ukraine says Russian forces controlling the strategic region of Crimea are demanding that the crew of two Ukrainian warships in Sevastopol's harbor must surrender. (Photo by Ivan Sekretarev/AP Photo)

A six-year-old acrobat performs on the opening of a tourist festival in Bozhou, Anhui province, China May 3, 2015. (Photo by Reuters/China Daily)

A protestor gestures toward the White House on the Ellipse near the South Lawn of the White House during the Women's March on Washington January 21, 2017 in Washington, DC. Large crowds are attending the anti-Trump rally a day after U.S. President Donald Trump was sworn in as the 45th U.S. president. (Photo by Drew Angerer/Getty Images)

Sarah Bui poses for photographer, Brian Le around blossoming cherry trees, near the Tidal Basin on Thursday March 23, 2017 in Washington, DC. (Photo by Matt McClain/The Washington Post)

Festival goers having fun at the Balaton Sound music festival in Zamardi next to the Lake of Balaton, 110 km (68 miles) west of Budapest, July 6, 2017. (Photo by Zsolt Furesz)

A woman dressed for la “La Diablada” festival walks down a road in Pillaro, Ecuador, Friday, January 6, 2017. Local legend holds that anyone who adopts a costume for the celebration and wears it at the event six years in a row will have good luck. (Photo by Dolores Ochoa/AP Photo)

Anna Sloan and Vicki Adams of Britain sweep during a match against Olympic Athletes from Russia in Session 1 of the Women' s Round Robin curling competition at the 2018 Winter Olympic Games at Gangneung Curling Centre in Gangneung, South Korea on February 14, 2018. The British team won the match convincingly, 10-3. (Photo by Cathal McNaughton/Reuters)