A Gender-bender Colored Cardinal

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Fans of the baseball Cardinals might have thought the bird Larry Ammann observed in January was dressed for a home game and an away game at the same time. The cardinal was half red and half gray.

Normally male cardinals are a bright, flashy red. Their fancy feathers may help them stand out and attract the more modestly dressed females.

Females are usually a mixture of gray, light-brown and red. But the cardinal Ammann saw was male-colored on the left, but female-colored on the right. The bird also sported a crest on its head usually reserved for males.

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Ammann, a statistics professor at the University of Texas in Dallas, spotted the bird at his backyard feeder one morning and was puzzled, because he only saw the gray side but also noted the bright red crest.

“Intrigued, I continued to watch until she turned around so I could see her other side. Suddenly, what originally seemed to be a female cardinal now looked just like a male!” said Ammann in his firsthand account.

He rushed to grab his camera to document the confusingly colored cardinal. The complete collection of photos, along with other avian art and brilliantly colored satellite imagery, can be seen at Remote Sensing Art.

After snapping a single shot, Ammann watched as the cardinal flew away. But that was all the evidence he needed to start solving this mystery of the two-tone cardinal.

“In just a few hours I learned, in a reply to one of my Web queries, that this bird is an extremely rare bilateral gynandromorph cardinal,” Ammann said.

“Quite a mouthful to say, but this means a genetic mistake occurred during the first cell division of the fertilized ovum, causing one of the cells produced by this division to be male and the other to be female. As this egg developed, the entire right side remained female and the left side remained male,” Ammann continued.

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This condition isn't unheard of in other birds, but is particularly noticeable in cardinals.

“The obvious differences in coloration between male and female cardinals, referred to as sexual dimorphism, makes gynandromorphy very noticeable when it occurs in cardinals,” he explained.

Over the next few weeks, Ammann took many more photos. He found himself growing attached to his rare visitor.

“I wondered if it felt as confused as it looked and if it is doomed to live a lonely existence,” Ammann said.

Ammann noticed another mystery as he observed the bicolored bird. Most cardinals are very vocal, but the gynandromorph cardinal didn't seem to sing.

“During those six weeks it visited my feeder, I looked for it whenever I heard a cardinal singing or chirping around our yard, but always the bird I heard turned out to be a normal cardinal, not this cardinal,” said Ammann.

Like Hermaphroditus, the Greek god who was both male and female, this cardinal showed physical signs of being both genders. But did it behave like a male or a female? Ammann noticed several behavioral clues.

While observing the cardinal, he noticed that male cardinals would try to chase it out of their territory as soon as they saw it. Females, however, were not bothered by it.

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The only way really to get to the bottom of this mystery was to analyze the DNA of the bird.

“An ornithologist at a neighboring university who specializes in the genetics of birds arranged for me to set up a net trap that would enable him to extract a feather from each side and obtain a blood sample, after which it would be released,” Ammann said. “DNA and blood testing would contribute to our understanding of this condition and its causes, so this bird’s appearance here provided a unique opportunity for scientific study.”

“Frustratingly, right after the trap was set up, our resident male cardinals started to exhibit territorial behavior and chased it whenever they saw it near the feeder. So we never were able to capture it,” said Ammann.

He hopes the cardinal has found somewhere it can live in peace, without being harassed by territorial males. Perhaps it has even found a mate … but of what gender, he wonders.

The gynandromorph cardinal may return in winter, once the territorial behaviors of the other males have subsided. Then ornithologists may get the opportunity to study this rare condition, and bird-watchers may get to see more of one of nature's mysteries.

“I know I will be looking for it then. So whenever you see a cardinal, make sure you look at both sides. You may be as pleasantly surprised as I was on that January morning,” Ammann said.

IMAGE 2: A male cardinal

IMAGE 3: A female cardinal

All other images are of the gynandromorph cardinal.

All images shown with copyright permission from Larry P. Ammann.

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