Kapparot, the sacrifice of hens may be traced to sacrifices in the ancient temple. It may be a remnant of pagan practices and superstitions. It's not quite clear. This is the prayer recited as the live chicken is waved three times above the head just prior to it being butchered: “This is my exchange, this is my substitute, this is my atonement. This chicken will go to its death while I will enter and proceed to a good long life, and peace“.
Although most Israeli Jews substitute chicken-based Kapparot with a monetary donation to the poor recent surveys have determined that over 60% of secular Israeli Jews do indeed fast on Yom Kippur, preserving a tradition passed down over the generations.