Like British secret agent James Bond, you love Black Copper Marans eggs for breakfast on blue china -- so you purchase Marans chicks. But, did the breeder send female or male chicks? A four-to-six-week wait yields a definitive answer. Male Marans chicks will eventually crow; females famously lay dark-chocolate-brown eggs. Other than waiting, people rely on four strategies for sexing: feather color and patterns, venting, surgical sexing and DNA testing. Of the four options, the least reliable is feather sexing. DNA testing leaves no doubts.
Sexing by Feathers
Most poultry chicks are monomorphic: Both sexes look the same after hatching. Researchers at the Mississippi State University Extension Service note that some specific breeds of chicks show feather differences, but those differences are "determined by specially selected genetic traits that must be present in the chick strain" -- and most chicken breeds don't have those kinds of traits, including the Marans, whose genetic history goes back to 12th century Marans, France, when Asian gamecocks mated with feral land chickens.
The Japanese developed the technique of vent sexing chicks. Vents, called cloacae, are small openings on the underside of birds used for elimination and fertilization, and, in hens, for delivering eggs. Trained venters feel tiny bumps in the vents of male chicks 24 hours after hatching. Expert venters exhibit accuracy rates of 95 percent to 98 percent, but it takes several years of practice to gain such skills. Beginning learners of the technique exhibit an accuracy level of no better than 60 percent. Done inappropriately, vent sexing can injure a chick.
Surgically sexing a bird by a technique called laparoscopy requires anesthesia and and requires making an incision on the left side of the bird. Experts using laproscopes or otoscopes can identify testicles of a young male, but they cannot easily identify ovaries in young females. Istanbul University geneticists Harun Cerit and Kozet Avanus, in a paper titled "Sex Identification in Avian Species Using DNA Typing Methods," note sexing a bird surgically could potentially damage vital organs, and in some cases such a procedure could prove lethal. The procedure is also costly.
Owners of companion birds, like parrots, often rely on DNA sexing. Birds donate blood through a clipped toe nail. Owners of Marans chicks can use avian lab services to sex chicks using DNA evidence. Results come back within days. Getting a blood sample does not cause serious injury. DNA testing has a 99.9 percent accuracy rate. The cost of DNA-sexing large broods of birds could be deterring. Depending on the lab, testing a single chick can cost anywhere from $12 to $25.