Frank Banta 
When Whirlybirds Call [EPUB ebook] 

The whirlybirds were predators. They ate the vicious animals like tigers and bears. But when their prey was exhausted, they turned to people. Today the crowd cheered from their windows to welcome the convertible, solo-spacecraft.  Five-gun Charles De Crabbe was flying into town to save the day.

When Whirlybirds Call, a Science Fiction Classic, was written by Frank Banta and first appeared in the Worlds of If Science Fiction magazine in January 1963.