Here is what I found on Bitter Almonds. It is not legal to sell then in the US, but other countries still use them. THEY ARE A DEFINITE NO FOR OUR BIRDS.
"Unlike sweet
almonds, bitter almonds need to be processed in order to extract a sweet almond flavor. Without processing or cooking, raw bitter almonds can be lethal.
The Danger of Bitter Almonds
Bitter almonds are a variety of regular, sweet almonds. Bitter almonds contain traces of prussic acid—also known as hydrocyanic acid—in its raw state. Hydrocyanic acid is a solution of hydrogen cyanide and water. The byproduct is an organic version of the well-known poison, cyanide. The worst symptoms of eating bitter almonds can include your nervous system shutting down, breathing difficulties, and even death.1 As few as seven to 10 unprocessed bitter almonds can kill a child, and roughly a dozen to 70 nuts can kill a 150-pound adult. The exact number depends on the size of the nuts. "
Cooked bitter almonds are used to make almond extract, marzipan, and cookies outside of the U.S. But they cannot be sold unprocessed in the United States due to their toxicity when raw.
www.thespruceeats.com