That's The Sparrow in the Zoo, Howard Nemerov, which I first learned from my daughter, visiting at the Washington zoo with her boyfriend some years ago. It struck me so funny I remembered it on the spot (but I refreshed my memory here). Today the boyfriend, now her husband, is due back at the zoo with their two teen-aged sons.No bars are set too close, no mesh too fine
To keep me from the eagle and the lion,
Whom keepers feed that I may freely dine.
This goes to show that if you have the wit
To be small, common, cute, and live on shit,
Though the cage fret kings, you may make free with it.