The Astonishing Tale of the Bilateral Gynandromorph Northern Cardinal

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(Photo Credit: Inland Bird Banding Association via WTKR)

A Rare Avian Marvel

In the quiet woodlands of northwest Pennsylvania, a feathered enigma flits among the branches—a creature that defies the ordinary, a living testament to the intricate dance of genetics. Meet the bilateral gynandromorph Northern Cardinal (Cardinalis cardinalis), a bird that wears its duality with grace and intrigue.

What Is Bilateral Gynandromorphism?

Imagine a cardinal painted down the middle: one half adorned in the warm, earthy hues of a female cardinal, while the other half boasts the fiery red plumage of a male. This striking specimen is a gynandromorph—a creature that embodies both genders simultaneously. Half male, half female, it stands as a testament to the complexity of life’s blueprint.

A Once-in-a-Lifetime Encounter

James R. Hill, III, a seasoned birder with 48 years of avian adventures, recounts his serendipitous encounter with this extraordinary cardinal. It was February 20, 2021, when he and Annette Smith embarked on a quest to document the rarest of birds. Their destination: a home near Grand Valley, PA, where an unusual visitor frequented the bird feeders.

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The Cardinal’s Split Identity

The homeowner’s description piqued Hill’s curiosity. She spoke of a male Northern Cardinal with “some white on its breast.” But this was no ordinary leucistic bird. Through the window, Hill glimpsed a cardinal that defied convention—a bilateral gynandromorph. Its left side bore the unmistakable features of a female, while its right side blazed with the crimson glory of a male.

A Genetic Marvel

How does a bird become a bilateral gynandromorph? Dr. Daniel Hooper, a postdoctoral fellow at the Cornell Lab of Ornithology, unravels the mystery. Unlike mammals, where males carry one X and one Y chromosome, birds follow a different script. Their sex chromosomes—Z and W—assign the opposite roles. Females possess a single copy of each (ZW), while males wield two identical copies (ZZ).

The Cardinal’s Dual Destiny

This unique cardinal harbored a functioning ovary on its left side and a single testis on its right. Theoretically, it could mate with a normal male cardinal and lay fertile eggs. Alternatively, it might court a female cardinal and father her offspring. The possibilities danced like sunbeams through the forest, illuminating the cardinal’s dual destiny.

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A Rarity Shared

Remarkably, this wasn’t the first bilateral gynandromorph to grace Pennsylvania’s skies. In 2019, a similar cardinal visited a couple’s bird feeders in nearby Erie, PA. Their photos made headlines, gracing the pages of National Geographic, the New York Times, and birding magazines. Could these two birds be kindred spirits, separated by miles but united by their extraordinary condition?

A Living Paradox

As we marvel at this cardinal’s split identity, let us celebrate the intricate tapestry of life. In its feathers, we glimpse the delicate balance of chromosomes, the dance of nature’s brush strokes. The bilateral gynandromorph Northern Cardinal—a living paradox, a testament to the wild beauty that defies our expectations.

And so, dear reader, the next time you spot a cardinal perched on a branch, remember: beneath those crimson wings lies a story—a tale of duality, resilience, and the magic that unfolds when genetics takes a whimsical turn.


  1. Erie Bird Observatory: A second bilateral gynandromorph Northern Cardinal in northwest Pennsylvania!
  2. JSTOR Daily: The Mysterious Gynandromorph
  3. Snopes: Does This Photo Show Half-Male, Half-Female Cardinal?
  4. BBC News: Rare bird: ‘Half-male, half-female’ cardinal snapped in Pennsylvania

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