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: Greater flamingos at Ebro Delta, Catalonia. (Photo by Xavi Bou/Rex Features/Shutterstock)





White storks at the swamp of Empordà, Catalonia. (Photo by Xavi Bou/Rex Features/Shutterstock)





A common tern at Ebro Delta. (Photo by Xavi Bou/Rex Features/Shutterstock)





Audouin’s gull at Ebro Delta. (Photo by Xavi Bou/Rex Features/Shutterstock)





Red-billed choughs at Utxesa swamp, Catalonia. (Photo by Xavi Bou/Rex Features/Shutterstock)





A black-winged stilt at Ebro Delta. (Photo by Xavi Bou/Rex Features/Shutterstock)





European herring gulls at Llobregat Delta. (Photo by Xavi Bou/Rex Features/Shutterstock)





A European herring gull at Ebro Delta. (Photo by Xavi Bou/Rex Features/Shutterstock)





Common starlings at Utxesa swamp. (Photo by Xavi Bou/Rex Features/Shutterstock)





A little egret at Ebro Delta. (Photo by Xavi Bou/Rex Features/Shutterstock)





Great cormorants at Ibars swamp, Catalonia. (Photo by Xavi Bou/Rex Features/Shutterstock)





Common swifts in Barcelona, Catalonia. (Photo by Xavi Bou/Rex Features/Shutterstock)