Starlings come home to roost on Brighton's Old Pier as the sun sets on December 21, 2011 in Brighton, England. December 21 marks the winter solstice, the shortest day of the year. (Photo by Dan Kitwood/Getty Images)

A man carrying butchered dogs drives past a pet dog at a dog meat market in Yulin, Guangxi Autonomous Region, June 21, 2015. (Photo by Kim Kyung-Hoon/Reuters)

Morenada dancers perform during the “Senor del Gran Poder” (Lord of Great Power) parade in La Paz, May 21, 2016. (Photo by David Mercado/Reuters)

Friends outside the convention center during opening day of the annual Comic-Con International in San Diego, California, United States July 21, 2016. (Photo by WENN/SIPA Press)

Ahmed, a 10-year-old jockey, looks on during the opening of the International Camel Racing festival at the Sarabium desert in Ismailia, Egypt, March 21, 2017. (Photo by Amr Abdallah Dalsh/Reuters)

A Thai wildlife department official carries a long-tailed macaque to a cage at a village in Bangkok, Thailand, September 21, 2015. Thai authorities were relocating the long-tailed macaques on Monday to lessen conflicts with the local community. (Photo by Chaiwat Subprasom/Reuters)

David Nicholson, 21, surfs as "The Mask" during the ZJ Boarding House Haunted Heats Halloween Surf Contest in Santa Monica, California, United States, October 31, 2015. (Photo by Lucy Nicholson/Reuters)

Iraqi security forces ride in vehicles travelling to Mosul to fight against militants of Islamic State at an Iraqi army base in Camp Taji in Baghdad, February 21, 2016. (Photo by Ahmed Saad/Reuters)