Jo-Anne McArthur’s book of photographs puts the spotlight on ethics of zoos around the world. Accompanied by essays by Born Free Foundation’s Virginia McKenna and philosopher Lori Gruen, the images and stories are also shared online through “A Year of Captivity”. Here: Asian Elephant, Denmark, 2016. (Photo by Jo-Anne McArthur/Born Free Foundation/The Guardian)

Neil Zeller's snaps were taken across Canada, where he photographs the northern lights dancing across a dark night sky. In one stunning shot, Zeller, 42, even manages to capture a flash of lightning beneath a storm cell while an aurora gives off a magnificent green glow. The photographer, from Calgary, Alberta, describes himself as a night person, and became interested in night photography about 10 years ago. (Photo by Neil Zeller/Caters News)

A White Crested Poland is seen at the National Poultry Show on November 20, 2016 in Telford, England. The annual event continues to grow with around 7000 entries this year from all around the world. (Photo by Leon Neal/Getty Images)

A participant dressed in a traditional devil costume walks from house to house during the traditional St. Nicholas parade on December 3, 2016 in village of Francova Lhota, Czech Republic. This type of parade is one of the most popular age-old traditions in a few villages in the Wallachia region of Eastern Czech Republic. St. Nicholas and company roam the streets going from house to house, for two or three days as St. Nicholas gives sweets and tiny gifts as a present to children and the devils get up to mischief. (Photo by Matej Divizna/Getty Images)

A boy holds the remains of a mortar shell which hit a residential building in the village of Staromikhailovka, outside the separatist-held city of Donetsk, Ukraine, May 24, 2016. (Photo by Alexander Ermochenko/Reuters)

Frog legs it! Indonesian flying frog tries to hitch a ride on snail's back before realising it would be quicker to hop it alone. A tiny frog struck up an unlikely friendship with a giant African land snail after clambering onto its shell to catch a ride. (Photo by Hendy Mp/SOLENT/Visual Press Agency)

Lida Maisuradze, 82, (L) and Zurab Gogidze, 82, celebrate after wining the “Super Grandmother and Super Grandfather” contest in Tbilisi, January 5, 2015. Twenty-two participants aged over 70 from all over Georgia competed in the annual contest organised by charity house Catharsis. (Photo by David Mdzinarishvili/Reuters)

Brides and grooms sit on top of an Indonesian Army vehicle during a mass wedding ceremony organized in Jakarta, Indonesia, Wednesday, January 28, 2015. More than 5000 couples participated on a mass wedding ceremony to legalized the previous religious marriage ceremonies. Most of the couples have not officially registered their marriage for economic reasons as it cost up to 500,000 IDR (35 euro) to legalized a marriage. The ceremony organized by Rajawali Foundation. (Photo by Achmad Ibrahim/AP Photo)