An opposition activist clashes with the police during a march against Venezuelan President Nicolas Maduro held on May Day, in Caracas on May 1, 2017. Security forces in riot vans blocked off central Caracas Monday as Venezuela braced for pro- and anti- government May Day protests one month after a wave of deadly political unrest erupted. (Photo by Federico Parra/AFP Photo)

Kea are the only true alpine parrots in the world and thrive as cunning opportunists in the freezing conditions of the Southern Alps. Kea are thought to have developed their wide array of food-finding strategies during the last great ice age, where they learned to adapt using their unusual powers of curiosity. (Photo by Tom Walker/BBC Pictures/The Guardian)

Indian devotees carry their luggage and wade through the flooded water in Varanasi, India, Friday, August 26, 2016. (Photo by Tsering Topgyal/AP Photo)

In this photograph taken on February 18, 2016, Pakistani children ride on swings in the predominantly Pashtun Korangi District of Karachi. In a rundown district of Karachi, Rabia balks at a neighbour's proposal to vaccinate her children, demonstrating one of the biggest hurdles to eradicating polio in Pakistan by the end of the year: confused and frightened parents. (Photo by Asif Hassan/AFP Photo)

A farmer harvests broccoli in the town of al-Ansariyeh south of Sidon, Lebanon March 15, 2016. (Photo by Ali Hashisho/Reuters)

An aircraft passes over houses at it lands at Heathrow Airport near London, Britain, December 11, 2015. Picture taken December 11, 2015. (Photo by Neil Hall/Reuters)

Britain's Queen Elizabeth boards a train at Kings Cross station in London, in this December 17, 2009 file photo. Queen Elizabeth celebrates her 90th birthday on April 21, 2016. (Photo by Stefan Rousseau/Reuters)

A member of the 324 Squadron during the Anzac Day dawn service at Coogee Beach in Sydney, Australia on 23 April 2019. Anzac Day, held annually on 25 April, is a national day of remembrance across Australia and New Zealand, which commemorates the people who lost their lives or served in wars and conflicts. The day coincides with the first landing of the Anzacs at Gallipoli, Turkey, in World War One. (Photo by Steven Saphore/Australian Associated Press)