These people are purchasing live chickens (packed in the yellow crates) for the controversial annual ritual of kapparot practiced by some Orthodox Jews in the days leading up to Yom Kippur. In this custom, a chicken is "swung" ("waved" is a more accurate description, as you can see in this NY Times video) three times above one's head, symbolically transferring one's sins to the bird, and then slaughtered. In some cases, the meat is donated to those in need (some articles I've read say this rarely happens, while others say it usually does). In recent years, a growing number of animal rights activists and rabbis have been vocally denouncing kapparot as a cruel practice that violates the Jewish prohibition against the infliction of unnecessary pain on animals. They encourage instead the following of an alternative tradition in which money is used in place of a chicken.