“Everyone was talking about how there was a need for diapers,” she says, given that chickens typically can’t be potty trained. “Oh, lord, what a mess they make.”

Ms. Haldeman, who is also a full-time chemist, designed a chicken diaper with a replaceable liner. She says it takes her about an hour to stitch one together, and her diapers are available in a variety of colors and patterns, such as rainbow and camouflage. She usually charges between $9 to $14 depending on a bird’s size. Buyers hail from cities such as New York and Tacoma, Wash., and as far away as New Zealand.