Rare Bird Has Half-Female and Half-Male Physical Characteristics

A rare Rose-breasted Grosbeak gynandromorph was caught and banded by biologists from Powdermill Nature Reserve, Carnegie Museum of Natural History's environmental research center in Rector, PA. This rare bird has both the male and female plumage, split down the middle.

On one side of the bird flaunts the yellow wing pits and on the other side is a pink underwing. The researchers believe that this gynandromorph songbird is a very unique one, as only a few of them were recorded. They think that this bird is a product of genetic anomaly, although more tests are needed to prove this claim.

Rare Bird Has Half-Female and Half-Male Physical Characteristics

(Photo: YouTube)
Half Male, Half Female Bird - Bilateral Gynandromorph Rose-breasted Grosbeak - Birding News Screenshot from YouTube/LycoBirds

Rare Gynandromorph Bird

Gynandromorphs have contrasting sexual characteristics on each side of their body, unlike true hermaphroditism, which has both the male and female reproductive organs.

In the bird's case, one side of its body appears to be female, and the other side shows male characteristics. In addition, the back of its wings and tail have crucial sexual differences in which the left side displays a browner shade while the right side is a blacker one.

Program manager Annie Lindsay said that the entire banding team was so excited to see such a rare bird up close. They also think that if the division of the male-female characteristics on the bird is the same with other gynandromorphs found in the past, then it might go for its insides too, including its brain and reproductive tissues.

According to the database of the Powdermill Avian Research Center, over the thousands of birds they have been banding since 1962, only less than ten bilateral gynandromorphs were recorded. The last time the center has seen a gynandromorph bird was in 2005, wherein another rose-breasted grosbeak displays half-male and half-female features also with one pink and one yellow underwing.

Gynandromorphy Among Animals

Gynandromorphy is an extremely rare condition in which animals display both male and female characteristics. This strange phenomenon was also seen in other animals other than birds; this includes reptiles, butterflies, and crustaceans. Scientists are still uncertain about how this phenomenon occurs.

In the past, some believed that gynandromorphs were formed from the fusion of two developing embryos that were fertilized separately. But there is a more recent idea that tries to explain gynandromorphy.

A female produces an egg cell in which half of its chromosomes are meant to be discarded in the polar body. However, it forms its own nucleus when the egg keeps this polar body of DNA.

Then, if two sperms fertilize the egg with two nuclei rather than one, this nuclei then starts dividing each side of the offspring's body, theoretically having its own sex. One part expresses the female chromosomes, and the other part expresses male chromosomes.

One issue with gynandromorphs also is whether they are capable of breeding. Usually, only the left ovary is functional in birds, and since the left side of the recently found bird is the female side, there is a possibility that the bird could reproduce if it successfully mates with a male.

Some half-sider birds with female characteristics on the right side are usually infertile. But even with a functioning ovary, scientists think that this bird might find it challenging to mate because male grosbeaks rely on their music to attract females. It is unclear whether this bird can attract any partner if its song sounds confusing to others.