Just how rare is this half-female, half-male bird sighting?

Every year toward the end of spring and beginning of summer, small bobolink songbirds travel thousands of miles north from their winter homes in Brazil and Argentina to breed. This year when they passed through Chicago, one conservationist spotted an incredibly rare one in their midst: it sported the classic male black-and-white pattern on one side and the classic female brown plumage on the other. This bobolink was a bilateral gynandromorph, meaning it was split right down the middle between both male and female genetic characteristics.In the Loop hears from the conservationist who first spotted and named this incredibly rare bobolink.GUESTS: Luke Dahlberg, conservation seed program manager at Citizens for ConservationProf. Brian Peer, chair of the biology department at Stephen F. Austin State University