Biologists Make 'Once-In-A-Lifetime' Discovery of a Bird That’s Half-Male and Half-Female, Say It Was Like 'Seeing a Unicorn'

In 2020, biologists in Pennsylvania got their hands on a rare bird that exhibited both male and female characteristics. The bird with these unique characteristics was a rose-breasted grosbeak (Pheucticus ludovicianus), Live Science reported.

Researchers working at the Carnegie Museum of Natural History's Powdermill Nature Reserve were pleasantly surprised when they spotted the bird. After analysis, the bird was immediately released by the team.

At the time of its spotting, researchers were involved in an activity called bird banding. It is a practice conducted by experts to identify and keep track of individual birds, the Smithsonian National Zoo reported.

In this process, experts put aluminum bands on the legs of each bird that visited a particular area. Just like license plates, each band had a unique set of numbers. The bands helped researchers keep a check of every bird they came across, and also note any changes. The method was expanded in later days, to incorporate features like characteristics and sex in the label.

The bird visited the reserve in September of that year and at first glance captivated the experts, Forbes reported. It seemed as if the bird was two halves stuck together, with one half belonging to a male while the other one was of a female. They identified the bird to be a 'gynandromorph' more commonly called halfsider.

"We carry walkie-talkies around the nets with us, and the field tech radioed back to excitedly say that they had a gynandromorph," Annie Lindsay, Bird Banding Program Manager, and a doctoral candidate, at the University of Toledo shared. "[A]nd sure enough, when they brought it back, it was a half male, half female Rose-breasted Grosbeak!"

According to experts, gynandromorph birds are rare to find. Lindsay calls the spotting a "once-in-a-lifetime experience." Until the spotting in 2020, Powdermill Nature Reserve’s avian research center captured around 750,000 birds in six decades. Among them, only ten were bilateral gynandromorphs.

"The banding team was starstruck by this bird," Lindsay added. "One of the crew said it was 'like seeing a unicorn'; one described the adrenaline rush lasting the whole day; one talked about how they 'never thought I’d see something so cool in my life'."

The color of the feathers is how experts usually identify the sex of rose-breasted grosbeak birds, Live Science reported. Scientists observed that this particular bird sported pink wing "pits", a red breast splash, and black wing feathers, on the right side of their body. All of these are characteristics associated with males.

At the same time, the bird also had brown shades on the left wing and yellow pits on the corresponding side. All of these are reflections of female rose-breasted grosbeaks. The scientists kept the bird in their custody for some time. They recorded their age, sex, and body measurements and took their feathers for genetic analysis in that duration. The bird was released after all the processes were done.

The next aim of researchers was to understand the bird's reproduction cycle. "In female songbirds, the left ovary is the functional ovary, and because this bird's left side is the female side, it may be able to produce viable eggs," Lindsay explained. "However, the bird would also need to behave as a female to attract a male mate, and that isn't something we are able to observe during normal banding operations," she added.