"Canaries won't sing without it."
That was what the bird seed companies testified before the US Congress in 1937. Due to that testimonial sterilized hemp seeds were imported for use in commercial birdseed mix even though hemp itself was illegal. Hemp seed has remained a major component of commercial birdseed mix to this day. Most pet birds eat hemp seed before the other seeds it's often mixed with. Pets need it to maintain healthy skin and feathers; and so do wild birds. (The lack of hemp seed may be one of the factors contributing to the decrease of the North American songbird population.) Hemp seed is also good food for people.
This is a part of an larger article, the author is unknown to me but the author holds the copyright nevertheless.