By Cheyenne Macdonald For Dailymail.com
Published: 19:57 GMT, 1 February 2019 | Updated: 20:27 GMT, 1 February 2019
With its body turned to one side, you might not notice anything unusual about the cardinal recently spotted in the backyard of two Pennsylvania bird enthusiasts.
But viewed head on, it’s an entirely different story.
The rare bird has the features of both a male and female cardinal, with its bright red coloration abruptly ending in a line that runs right down the middle of its body, where it becomes a much more subdued blondish-brown.
The bird's striking appearance is the result of double fertilization, in which a female egg cell that developed with two nuclei is fertilized by two sperm. The result is what’s known as a bilateral gynandromorph
A cardinal spotted recently in Pennsylvania that appears to be half-male and half-female has shed light on the phenomenon of gynandromorphs.
They're not all that uncommon in the wild, though the coloration or markings of some species make the results more striking than others.
A gynandromorph is an organism that has both male and female characteristics - or, a male-female chimera.
It's often seen in insects, though gynandromorph birds, snakes, and other animals have been observed too.
Pennsylvania residents Jeffrey and Shirley Caldwell spotted the incredible half-male half-female cardinal in a dawn redwood