Yak near Yamdrok lake, Tibet. It is a long-haired bovinae found throughout the Himalayan region of south Central Asia, the Tibetan Plateau and as far north as Mongolia and Russia. The Tibetan economy is dominated by subsistence agriculture. Due to limited arable land, the primary occupation of the Tibetan Plateau is raising livestock, such as sheep, cattle, goats, camels, yaks, dzo, and horses. The Tibetan yak is an integral part of Tibetan life. (Photo by Dennis Jarvis)

Migrants ride on top of a northern bound train toward the US-Mexico border in Juchitan, southern Mexico, Monday, April 29, 2013. Migrants crossing Mexico to get to the U.S. have increasingly become targets of criminal gangs who kidnap them to obtain ransom money. (Photo by Eduardo Verdugo/AP Photo)

Female soldiers with their faces painted in the colours of the Venezuelan flag, march during a military parade to celebrate the anniversary of Venezuela's independence in Caracas, July 5, 2015. (Photo by Jorge Dan Lopez/Reuters)

Two wolfhounds take part in a dogfight in a stadium in the Kyrgyzstan capital Bishkek on November 5, 2017, during fights organized by a local breeders aiming to improve the Asian Shepherd breed, organizers said. (Photo by Vyacheslav Oseledko/AFP Photo)

An Iraqi girl walks past a donkey-drawn cart carrying bricks at a brick factory near the central Iraqi shrine city of Najaf on May 16, 2017. (Photo by Haidar Hamdani/AFP Photo)

People walk next to of the pantheon of the Marquesa de San Juan de Nieva, chosen as the best tomb sculpture of Spain in a Spanish magazine this week, in the municipal cemetery of La Carriona in Aviles, northern Spain, October 29, 2015. Catholics will mark All Saints' Day on Sunday by visiting cemeteries and graves of deceased relatives and friends. (Photo by Eloy Alonso/Reuters)

A Palestinian man reacts after his house was flooded by rain water in Khan Younis in the southern Gaza Strip, November 9, 2015. (Photo by Ibraheem Abu Mustafa/Reuters)

This picture taken on November 18, 2015 shows young participants preparing to release a hot-air balloon during the Tazaungdaing Lighting Festival at Taunggyi in Myanmar's northeastern Shan State. Every year in November as the full moon approaches, tens of thousands of people from all over the country gather in Taunggyi for the colourful hot-air balloons festival during which balloons lift fireworks or lanterns which illuminate the sky at night while balloons of all shapes are flown during the day. (Photo by Ye Aung Thu/AFP Photo)