At least they didn’t go for the giant, spring-loaded needle traps.
The events that led teams of helicopter-borne vets to pelt the Swiss countryside with vaccine-impregnated chicken heads began in 1939. Two things were then sweeping through Poland: the Nazis, and an epidemic of rabies carried by red foxes. Every year, the wavefront of disease advanced southward and westward by several dozen kilometers, hitting country after country. In March of 1967, it reached Switzerland.
The epidemic was a huge problem. Rabies is caused by a virus that spreads through the bites of animals and targets the brain. Unless infected people get a (really expensive) vaccine right away, the disease is almost always fatal. So, something had to be done about the foxes. The usual methods—poisoning, trapping, gassing, and shooting—weren’t working. The alternative was to vaccinate them.