Bangladeshi Muslim devotees arrive in an over-crowded train to attend the final day of an Islamic congregations' first phase in Tongi, 20 kilometers (13 miles) north of Dhaka, Bangladesh, Sunday, January 10, 2016. The second phase of the annual event, one of the world's largest congregations of Muslims is scheduled to begin Friday. (Photo by A.M. Ahad/AP Photo)

The blue-footed booby (Sula nebouxii) is a marine bird in the family Sulidae, which includes ten species of long-winged seabirds. Blue-footed boobies belong to the genus Sula, which comprises six species of boobies. It is easily recognizable by its distinctive bright blue feet, which is a sexually selected trait. Males display their feet in an elaborate mating ritual by lifting their feet up and down while strutting before the female.

Pionneers from Aubagne's 1st Foreign Regiment (Legion etrangere) march the Champs-Elysees during the annual Bastille day parade on July 14, 2011 in Paris, France. The French National Day celebrates its revolution in the storming of the Bastille in 1789 through various parades and official ceremonies throughout France. (Photo by Franck Prevel/Getty Images)

A model presents a creation during a hair styling competition in Minsk, Belarus on November 9, 2017. (Photo by Sergei Gapon/AFP Photo)

One-day-old baby giraffe calf Gus looks at the camera at Noah's Ark farm on May 12, 2017 in Bristol, England. The baby giraffe was born yesterday at the zoo farm in North Somerset. In the wild, populations of giraffes are suffering from a continuing decline, with 97,500 estimated in Africa in 2015. Since 1985 the total giraffe population has fallen by 35%. New arrival Gus joins brothers George, 4 and Geoffrey, 2. (Photo by Matt Cardy/Getty Images)

People fly kites during the 2017 Pyostroye Nebo kite festival in Tsaritsyno Park in Moscow, Russia on August 27, 2017. (Photo by Asya Dobrovolskaya/TASS)

A woman dressed up for Halloween travels on a Metro train in São Paulo, Brazil on October 30, 2017. (Photo by Cris Faga/Rex Features/Shutterstock)

People look at a Christmas tree decorated with colourful lights at a residential compound in Beijing on December 8, 2017. (Photo by Nicolas Asfouri/AFP Photo)