A six-day-old hippopotamus is pictured next to his mother, Kara, aged 21, on September 12, 2012 at “Planet sauvage” (“Wild planet”) Zoo in Port-Saint-Pere, western France. The birth, a rare event for this species in captivity, occured on September 7, 2012 in the Zoo. (Photo by Frank Perry/AFP Photo)

Father Juan Manuel Villar blesses a dog during the feast of San Anton, the patron saint of animals, at the San Anton church on January 17, 2012 in the center of Madrid, Spain. San Anton is honored by many Catholic churches in Spain where thousands of animal lovers flock to their nearest place of worship to have their animals blessed. (Photo by Jasper Juinen/Getty Images)

People take part in a Halloween street party at Lan Kwai Fong on October 31, 2016 in Hong Kong. Halloween, a contraction of All Hallows' Evening, falls on the day before All Saints' Day on November 1, a holiday when Christians remember their deceased loved ones. (Photo by Lam Yik Fei/Getty Images)

An airplane is silhouetted at sunrise, seen from the suburb of Saint-Cloud, near Paris, France, 08 December 2016. Paris is undergoing a third day pollution spike, prompting the city to limit vehicle circulation. (Photo by Ian Langsdon/EPA)

An inmate with a tattoo of Santa Muerte (The Saint of Death) reacts in the Topo Chico prison, during a media tour, in Monterrey, Mexico, February 17, 2016. The director of a prison in northeast Mexico where 49 people died in a riot this week was accused of murder and detained, along with two others, a state prosecutor said on Saturday. (Photo by Daniel Becerril/Reuters)

A dancer dressed for the annual procession honoring San Pedro, his town's patron saint, runs through the street of San Pedro Sacatepequez near Guatemala City June 29, 2016. (Photo by Saul Martinez/Reuters)

The winners in the third annual drone photography awards have been announced. Organised by the social network Dronestagram, the competition attracted more than 6,000 entries from amateur and professional drone enthusiasts across the world. Here: First place in the travel category went to the Basilica of Saint Francis of Assisi in Italy. (Photo by Francesco Cattuto)