“Song in the Thicket” by Manly Banister.  Cover art by W. H. Silvey.

Yes, “Manly Banister” is indeed the author’s name.  He appears to have had several, so it’s a good bet this was a nom de plume.  (For comparison, his other names include “Gregg Powers” and, curiously, “Val Seanne.”)

Google him.  He … actually published a hell of a lot between 1942 and 1980.