National Geographic invites photographers from around the world to enter the 2013 National Geographic Photography Contest. The grand-prize winner will receive $10,000 (USD) and a trip to National Geographic headquarters in Washington, D.C., to participate in the annual National Geographic Photography Seminar in January 2014. Photo: “We just want to move to search to the Leopard at that morning but we found a group of giraffes come toward a small lake and start drinking it was a nice moment when the Giraffe finish from drinking and leave a letters “S” with motion in the air”. (Photo and caption by Majed Ali/National Geographic Photography Contest)

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)

No. 10: Sphynx. A suede-like coat is the sphynx's most unmistakable feature, but he's also curious, smart and a clown who craves applause for his antics. In fact, he loves attention so much that you may want to consider getting him a fellow sphynx playmate. (Photo by Quentin Descotte)

A Chinese vendor wears a rooster hat as he smokes a cigarette at his souvenir stall at a fair at Temple of Earth, on the eve of Chinese New Year February 8, 2005 in Beijing, China. Chinese started February 8, to celebrate the New Year of the Rooster. (Photo by Andrew Wong/Getty Images)

A dramatic sunset acts as a backdrop to Stonehenge on November 20, 2008 in Stonehenge, England. (Photo by Mike Hewitt/Getty Images)

Elena Reid of USA looks on with bloody face due to a cut during the Women's WIBF Flyweight Championship fight between Regina Halmich and Elena Reid at the Boerderlandhalle on December 3, 2005 in Magdeburg, Germany. (Photo by Christian Fischer/Getty Images)

A baby bush-baby in a set of scales at London Zoo shortly after birth. (Photo by Fox Photos/Getty Images). 10th August 1938