Two sheep fight in a competition in Zhangjiakou, Hebei province, China on August 1, 2017. (Photo by Reuters/China Stringer Network)

The front wheels of a tractor lift off the ground as the driver moves a heavy trailer outside Peshawar, Pakistan February 19, 2018. (Photo by Fayaz Aziz/Reuters)

Eight year-old Maya Mohammad Ali Merhi walks using prosthetic legs made by her father from tin cans in a camp for displaced people, in the northern Syrian province of Idlib on June 20, 2018. Maya and her father were both born without lower limbs. Unable to afford real prosthetic limbs, her father made her a pair out of tin cans filled with cotton and scrap pieces of cloth. Maya's family had to leave their home in the Aleppo province to flee battles. (Photo by Aaref Watad/AFP Photo)

MiG-15 jet fighters are pictured in Kucova Air Base in Kucova, Albania on October 3, 2018. Albania retired its 224 Soviet- and Chinese-made MiGs in 2005, and since 2009 NATO neighbors Italy and Greece monitor its airspace. That led to economic decline in and around Kucova, which was called “Stalin City” during the era of Communist rule. (Photo by Florion Goga/Reuters)

Cooler temperatures begin this week as a polar vortex brings much colder conditions with the chance of snow for Snowdonia, Ogwen Valley, North Wales on 22nd October 2018. The Ogwen Valley and Tryfan Mountain looking splendid in the Autumn sunrise. (Photo by DGDImages/Alamy Live News)

European bisons (also known as Wisent) at the Bison farm in Muczne, southeastern Poland, 30 December 2018. The Bison farm is a continuation of bison breeding in Bieszczady, which was started in 1963. Here visitors can admire the bison of Bialowieza-Caucasian line, also called the mountain race. The European Bison is the national animal of Poland. (Photo by Darek Delmanowicz/EPA/EFE)

An Emirati child plays with an airplane model near the venue of the Mazayin Dhafra Camel Festival, on December 20, 2012 near the city of Madinat Zayed, 150 kms west of Abu Dhabi. The festival, which attracts participants from around the Gulf region, includes a camel beauty contest, a display of UAE handcrafts and other activities aimed at promoting the country's folklore. (Photo by Karim Sahib/AFP Photo)

A young Chinese girl dressed in Christmas costume, hugs a pedestrian on a street to celebrate Christmas in Nanjing city, east China's Jiangsu province, 23 December 2015. (Photo by Imaginechina/Splash News)