Chloe is the deceased wife of Buck Cluck and the deceased mother of Chicken Little. Though it is not known how or when she died, she is mentioned throughout the film by her husband, her son, and his friends, despite being gone.
When Buck Cluck comes home from picking his son up from detention at the elementary school, she is briefly seen in a family photo, while Buck Cluck is saying "Oh, Chloe, if you were here... you'd know what to do".
Her son, Chicken Little, bears a striking similarity to her in appearance.
She could have died fairly recently prior to the movie, as they talk about her a lot, as someone would do when someone close to them died recently.