Spanish photographer Xavi Bou uses an antique photo-technique to freeze birds in flight

(CNN)Xavi Bou does not photograph normal things.

Some of the Spaniard's subjects look like sea creatures, raised from the deep and suspended into the evening sky. Others look like solid tornadoes, black, densely coiled and threatening. Some refuse description, other than to say they are altogether alien.
It might come as a surprise then to find Bou's photographs aren't just natural -- they're practically antique.
    Drawing on a technique developed in the mid-nineteenth century, Bou uses chronophotography to capture birds -- from egrets to alpine swifts -- in an otherworldly fashion.
    "[Chronophotography] captures movement in several frames," he explains. "The idea is to take as many pictures as possible to freeze every single movement of the object in motion."
    A horse galloping, by Eadweard Muybridge (1830 - 1904).
    Originally created for scientific purposes, it was once used by Eadweard Muybridge, a British photographer, in 1878 as definitive proof that horses did indeed gallop with all four feet off the ground.
    "The difference between traditional chronophotography and mine is that I try to overlap every frame, because I'm interested in the complete shape that's produced by the movement," Bou explains.
    Ornitographie 04#: Sturnus vulgaris, Common starling, Utxesa swamp, Catalonia
    Shooting with a high resolution digital camera, in post-production these shapes come together in a composite image hundreds of frames deep. But why?
    "[It] shows me the hidden beauty of nature," Bou argues. It's a fascination that harks back to his childhood, and a sense of wonderment he first felt when encountering birds on walks with his grandfather.
    "I called the series 'Ornitographies' because for me it looks like drawings done by birds in the sky," he explains. Not that the photographer expects us all to see the same.
    "From drawings to DNA, to fractals, wires [and] kites... it's important that everyone find their own meaning. You can find a more scientific approach or more poetic -- it's up to you."
    Bou's 'Ornitographies' continues, with the photographer planning to bring the series together into a book.