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)

The Capilano Suspension Bridge is a simple suspension bridge crossing the Capilano River in the District of North Vancouver, British Columbia, Canada. The current bridge is 140 metres (460 ft) long and 70 metres (230 ft) above the river. It is part of a private facility, with an admission fee, and draws over 800,000 visitors a year.

Finia, a visiting student from Hanover, cools off under a water sprinkler in front of the Chancellery on June 10, 2010 in Berlin, Germany. (Photo by Sean Gallup/Getty Images)

Some of London's telephone operators and engineers, trying out their gas masks at the anti-gas civilian training centre in Gloucester, where they were taught how to deal with gas attacks. (Photo by Harry Todd/Fox Photos/Getty Images). 13th February 1937

A woman walks with her baby past a PM militarized police soldier in position and aiming his rifle in Rocinha favela in Rio de Janeiro, Brazil on September 23, 2017. Although shooting was reported in the early hours of Saturday in Rocinha – for the seventh day running – officials said that Friday's deployment of 950 soldiers to reinforce police had brought the crisis under control. (Photo by Carl De Souza/AFP Photo)

A man carries schoolchildren on his bicycle on a road in Srinagar, March 28, 2017. (Photo by Danish Ismail/Reuters)

A worker walks beside the ocean liner Queen Mary II in a dock at Blohm&Voss shipyard in Hamburg, Germany, June 14, 2016. The mighty Queen Mary 2 is just days away from setting sail after the most expensive refurbishment of any ship in history. Tens of millions of pounds have been spent on the 151,200-tonne ship as 2,500 workers complete the month-long major interior overhaul. (Photo by Fabian Bimmer/Reuters)

Gina Labianca (L) tries on a super woman outfit as Charlie Lucas tries a snow white Costume at the Halloween MegaStore Miami Beach on October 21, 2011 in Miami Beach, Florida. The megastore is a temporary location for the store which opened for the holiday to sell costumes, masks and other items to people needing to dress up for the evening of October 31 when costumed people around the world observe the day. (Photo by Joe Raedle/Getty Images)