The Spanish photographer Xavi Bou digitally combines sequential pictures of birds to create a single image, or chronophotograph, that reveals the shapes of their flight paths against Catalonian skies. His work shows the variety and beauty to be found in the daily activities of the local birds, including spiralling storks, swooping starlings and giddy swifts. Here: European herring gulls at Llobregat Delta. (Photo by Xavi Bou/Rex Features/Shutterstock)

Students from St Andrews University are covered in foam as they take part in the traditional “Raisin Weekend” in the Lower College Lawn, at St Andrews in Scotland, Britain October 17, 2016. The weekend, which begins on Sunday, involves rituals for new students, culminating in a foam fight on Monday morning. (Photo by Russell Cheyne/Reuters)

A gun is seen next to the body of a man was killed in a shootout with police in Manila, Philippines early October 21, 2016. According to the police, sachets containing substance believed to be drug shabu (Methamphetamine Hydrochloride) were found in the killed man's pockets. (Photo by Damir Sagolj/Reuters)

A life-size sculpture of a pianist, made of approximately 210,000 matches and weighs around 100 kilograms, is seen in Tomislav Horvat's studio in Podturen, Croatia, October 27, 2016. For the last ten years, Horvat has built sculptures made from matches. This is his biggest sculpture to date that took him some 30 months to build. (Photo by Antonio Bronic/Reuters)

Nepalese police officers worship a dog during the dog festival as part of Tihar celebrations, also called Diwali, at the Central Police Dog Training School in Kathmandu, Nepal October 29, 2016. Dogs are worshipped to acknowledge their role in providing security during Tihar festival, one of the most important Hindu festivals that is also dedicated to the worship of the goddess of wealth Laxmi. (Photo by Navesh Chitrakar/Reuters)

2016 Rio Olympics, Rugby, Women's Semifinals Britain vs New Zealand, Deodoro Stadium, Rio de Janeiro, Brazil on August 8, 2016. Portia Woodman (NZL) of New Zealand tackles Claire Allan (GBR) of United Kingdom. (Photo by Phil Noble/Reuters)

Tree trunks and rocks are set up to support a leaning wall of Li Yonghua's damaged cave house in an area where land is sinking next to a coal mine, in Helin village of Xiaoyi, China's Shanxi province, August 2, 2016. (Photo by Jason Lee/Reuters)

Tourists from the Middle East take pictures at Vrelo Bosne nature park in Ilidza near Sarajevo, Bosnia and Herzegovina, August 19, 2016. They discovered mountainous Bosnia, where half the population is Muslim, after the Arab Spring which destabilized many traditional holiday destinations such as Libya, Tunisia and Egypt. (Photo by Dado Ruvic/Reuters)