The cyanide was hell on secondary kills by carrion eaters picking on the carcasses of the dead coyotes. I'm glad they stopped that.
Not sure what you are talking about. M-44 cyanide capsules are still used, and there is no secondary poisioning from the cyanide capsules. I believe you maybe referring to Compound 1080 (Sodium fluoroacetate) which was banned in 1972, but is still used today in very limited applications.
Also, those guys are still passing on their knowledge. They pass it on to the young guys working for them.