Photos: When animals yawn

A lion in the Edeni Game Reserve in Limpopo, South Africa, in 2010. (Cameron Spencer / Getty Images)

A white tiger cub at the Maubeuge zoo in France in 2010. (Philippe Hueguen / AFP/Getty Images)

Bonhomme, a male leopard from Sri Lanka, at the Bioparc of Doue-La-Fontaine, France, in 2012. (Frank Perry / AFP/Getty Images)

A Siberian Tiger in its enclosure in the Shanghai Zoo in 2014. (Johannes Eisele / AFP/Getty Images)

A jaguar at the El Picacho zoo, in Tegucigalpa, Honduras, in 2010. (Orlando Sierra / AFP/Getty Images)

A cat enjoys the spring sun in front of a house in Sieversdorf, Germany, in 2014. (Patrick Pluel / AFP/Getty Images)

A baboon in its enclosure at the Zoologischer Garten Berlin in 2011. (Johannes Eisele / AFP/Getty Images)

A Bengal tiger yawns in its enclosure in the Shanghai Zoo in 2014. (Johannes Eisele / AFP/Getty Images)

The San Diego Zoo's female giant panda cub Hua Mei, then 14 weeks, yawns during a veterinary exam in 1999. (San Diego Zoo)

An African lion lets out a morning yawn at Lions Tigers & Bears, a no-kill, no-breed and no-sell rescue and educational facility in Alpine that cares for mostly captive-bred animals that can't be released in the wild. (Don Bartletti / Los Angeles Times)

A dog yawns during a festive event against animal abandonment at Chueca's square in Madrid in 2012. Madrid's district of Chueca organized this event on the day of Saint Anthony, known as the protector of the animals. (Pierre-Philippe Marcou / AFP/Getty Images)

A young male lion yawns in the rain in Meru National Park. (Amanda Jones / For The Times)

A Canadian Sphinx cat yawns at the cat show SaxCat in the eastern German city of Chemnitz in 2011. (Hendrix Schmidt / AFP/Getty Images)

A lion cub yawns at the Lion Park in Johannesburg in 2010. (Mustafa Ozer / AFP/Getty Images)

A male baboon shows off his canine teeth to other males in Capetown, South Africa, in 2010. (Paula Bronstein /Getty Images)

A 13-week-old white lion cub plays with his mother, Nikita, in 2014 at the zoo in La Fleche, France. (Jean-Francois Monier / AFP/Getty Images)

A zookeeper holds a howler monkey baby at the zoo of Szeged, Hungary, in 2013. (Csaba Segesvari / AFP/Getty Images)