Completely unnecessary and cruel. Rabbi Karo, author of Shulchan Aruch called it a foolish custom to be avoided. For those who wish to do the minhag it should be done with money, instead of chickens. Tsa'ar ba'alei chayim.
Thanks for watching You seem very knowledgeable Hundreds of thousands of Jewish people perform this Minhag following Kabbalah. Feel free to research the topic. You are correct that Tzar Balei Chaim is against the Torah. We avoid that at all costs.
