A hen squirmed in Joel Lubin’s hands, but he held on and raised it over the head of his wife at noon on Thursday, as they stood on a sidewalk in the Williamsburg section of Brooklyn.

As Mr. Lubin turned the bird in three small circles over her head, his wife read from a laminated card. In front of her was a double-wide stroller with two children on board. Behind a barricade a few feet away were about 100 plastic crates full of live chickens. It may never be a good week to be a chicken — that is a deep, deep question, beyond the remit of this column — but let us say that the first days after the Jewish New Year are a particularly bad time to be one in parts of Brooklyn.

Between Oct. 4, the end of the Rosh Hashana observance of the new year, and Yom Kippur, the day of atonement starting the night of Oct. 11, an estimated 50,000 chickens will be sacrificed in Brooklyn as part of a penitential ritual performed by some Hasidic Jews.

The practice, called kaporos or kapparot, is meant to transfer a person’s sins to the chicken. “If you’re going to die during the year, maybe the chicken will die instead,” Mr. Lubin said. The chicken he rotated over his wife’s head was brought into the Cohn Live Poultry shop on Flushing Avenue, where it was slaughtered, made kosher and packed on foam butcher trays. “It goes to the poor,” Mr. Lubin said of the chicken.