February 2, 2019
Incredibly Rare 'Half-Male, Half-Female' Cardinal Photographed In Pennsylvania Garden

Birdwatchers have spotted a stunning, rare cardinal in a garden in Erie, western Pennsylvania. Perched on a branch in a backyard tree, bird enthusiasts have photographed a spectacular northern cardinal (Cardinalis cardinalis) that is "half-male, half-female," CBS Pittsburgh is reporting.

According to the National Geographic, the sensational creature is known as a bilateral gynandromorph — one of the rarest and most elusive occurrences in nature. The incredible bird has the colors of its plumage split right down the middle, exhibiting a bright vermilion shade on one side (the female half) and a deep taupe hue on the other (the male half).

The cardinal's striking appearance is the result of double fertilization, explains the National Geographic. Bilateral gynandromorphy in birds occurs when a female egg cell develops two nuclei, each carrying a different sex chromosome (Z and W), and is then fertilized by two sperm — both carrying the same Z chromosome.

Bird sex determination is the exact opposite of what happens in mammals, where it's the males who carry one copy of each sex chromosome (X and Y), whereas the females have two copies of the X chromosome.

A baby chick hatched from a double fertilized egg with two different ZW nuclei bares both male and female features. This makes it look as though two individuals of different sexes were stitched together, notes the Daily Mail.

"Cardinals are one of the most well-known sexually dimorphic birds in North America — their bright red plumage in males is iconic — so people easily notice when they look different," said Daniel Hooper, a postdoctoral fellow at the Cornell Lab of Ornithology.
"This remarkable bird is a genuine male/female chimera."
The wondrous sighting was first made a few weeks ago by birdwatching couple Jeffrey and Shirley Caldwell, who caught a glimpse of the magnificent cardinal perched in a dawn redwood tree some 10 yards from their home. The two have been studying and photographing birds for 25 years, yet this is the first "half-male, half-female" cardinal that they've ever laid eyes on.

"Never did we ever think we would see something like this in all the years we've been feeding," said Shirley.

The couple eventually managed to photograph the fantastic bird, which has since gone viral.

A pair of northern cardinals, female (left) and male (right).
A pair of northern cardinals, female (left) and male (right).

A similar case was described in a study published in 2014 by researchers in western Illinois. The scientists observed another male-female cardinal between December 2008 and March 2010 to see how it interacted with others and published their findings on its behavior in the Wilson Journal of Ornithology.

As it turned out, bilateral gynandromorphs lead very lonely lives.

"We never observed the bird singing and never saw it paired with another cardinal," Prof. Brian Peer of Western Illinois University, lead author of the study, said when the paper first came out.

"It was one of the most unusual and striking birds that I've ever seen."
However, it seems that this may not be the case for the male-female cardinal spotted in Pennsylvania. While the Caldwells didn't hear it sing either, they did, nevertheless, see the bird in the company of a male cardinal.

"We're happy it's not lonely," said Shirley.

According to Hooper, there's even a chance that this incredibly rare bird could reproduce. While bilateral gynandromorphs are infertile, this particular cardinal is female on the left side — which is where the only functional ovary exists in birds.

"Who knows, maybe we will be lucky enough to see a family in summer!" said Shirley.