Tallon Nightwalker of Fort Collins said his quest began when he was 5 and his father took his picture with a bullsnake he was working with at the Fort Collins wildlife sanctuary, The Denver Post reported Monday.
The teenager and his father, Bob Nightwalker, said they figure they have about 25,000 more pictures to take.
"There is no doubt this has brought us together," Bob Nightwalker said. "But just as importantly, I think Tallon is helping save many of these animals, many of whom some people have never heard of before."
Tallon has posted the pictures, which all feature living animals without barriers between boy and beast, on a Facebook page titled "Tallon Nightwalker's Animal Pictures."