Belle Benchley

These next two photos were discovered inside a used copy of MY LIFE IN A MAN-MADE JUNGLE, which I bought on-line. This first photo shows Belle Benchley and some tiger cubs born at the San Diego Zoo. On the back, the book’s owner had written in pencil “From Mrs. Belle J. Benchley, Executive Sec’y San Diego Zoo.” There is also a notation written in ink (probably by Mrs. Benchley herself) that reads “My latest babies.” The book’s owner also wrote his name on the back: E. May Caldwell. I looked this name up on-line: there was an artist with this same name, who might have been him. Does anybody know who he was?