It is one of Paul Simon's many tributes to his hometown of New York City, and was written for the soundtrack of The Graduate, specifically the scene which takes place at the San Francisco Zoo.
"[1] Cash Box called the single a "bright and lively mover that’s bound to be a smash.
"[3] "At the Zoo" was first released as a single in 1967, reaching number 16 on the Billboard Hot 100.
In 1991, Paul Simon released a children's book titled At the Zoo (ISBN 0-385-41771-3) which combines the lyrics of the song with detailed illustrations by Valerie Michaut.
To make this book "age-appropriate" for children, Simon made changes and additions, including identifying Rum as a beaver (because the original lyric states that "the zookeeper is very fond of rum") and giving the hamsters headlights (because they "turn on frequently").