Half-Male, Half-Female

An article in the NY Times, A Rare Bird Indeed: A Cardinal That's Half Male, Half Female, discusses the phenomenon of half-male, half-female cardinals. Not much is known about the occurrence, however, the sex split is reported among birds, reptiles, butterflies, and crustaceans. These such creatures are referred to as gynandromorphs. In cardinals, the distinction is more noticeable because the bird appears to be split right down the middle. This is because vertebrates develop in a bilaterally symmetrical manner. As a result, the cardinal resembles a male, scarlet-colored, on the side and a female, taupe-colored, on the other. Technically, each "side" of the bird would be the brother or sister of the other.

Female characteristics

Male characteristics 

Daniel Hooper, an evolutionary biologist at the Cornell University Lab of Ornithology, stated that "gynandromorphs could theoretically be created through the fusion of two developing embryos that were separately fertilized". It is also possible that the female produces an egg that possesses both copies of her sex chromosomes, Z and W, and then is fertilized by two separate sperms, each with a Z chromosome. In the bird species, females are represented by ZW and males by ZZ. However, scientists are still unclear on how an egg yields a progeny with both ZW and ZZ cells.

Additionally, the brain of the gynandromorphic cardinal is half-male, half-female. This lead scientists to wonder how this type of bird is able to learn, evaluate, and produce a bird song. This is because male songbirds have more neural connections than females in their brains in order to sing their complex tunes. Gynandromorphs are thought to be infertile. Some scientists have observed gynandromorphs pairing off with other birds of one distinctive sex. However, not enough research has been accomplished to determine whether the other bird was a mother or father or if the other bird would remain present for mating season. Birds only have functional ovaries on the left side, therefore, if a mixed bird was female on the left half, it could be possible for it to reproduce. Although. Dr. Hooper said that he would expect the offspring to be genetically conventional due to the fact that its egg cells would only have one sex chromosome.

More studies regarding gynandromorphs should be conducted because understanding this phenomenon could yield data to figure out why this occurs. In addition, more research could result in an answer to the question, can these mixed birds reproduce? These half-male, half-female cardinals have a unique appearance that could prove to be beneficial. The taupe color could provide camouflage from predators, while the signature red color could attract the right eyes. Maybe being different is not a bad thing...

Prehistoric Evolution of Birds

http://www.nytimes.com/2005/08/25/health/the-link-between-dinosaurs-and-birds.html

http://www.nhm.org/site/research-collections/dinosaur-institute/dinosaurs/birds-late-evolution-dinosaurs

Archaeopteryx; a very early prehistoric bird, dating back 150 million years ago during the Jurassic period, it is one of the oldest-known birds. Based on bone structure it looked to be part bird and part dinosaur. Unlike modern-day birds, it had teeth, three claws on each wing, a flat sternum, belly ribs, and a long, bony tail. However, like modern-day birds, it had feathers, a lightly-built body with hollow bones, a wishbone and reduced fingers. This animal may have been able to fly but if so not very far and not very well. Scientists took a look at dinosaur brains to trace this hyperinflation and they found that Archaeopteryx’s brain fell in between that of distantly related theropods, such as Tyrannosaurus rex, and living birds. 

I find this extremely interesting because birds may not be the smartest of all creatures but there are a variety of species of birds, each with it's own story. No matter where you go in the world you will always come across some type of bird, they fill the Earth and are able to live in any environment.  

Egg Being Fertilized By More Than One Sperm In Birds?

Birds' eggs are fertilized by more than one sperm, a process called polyspermy.  Studies have shown that more sperm in an egg is correlated with more viable offspring.  In birds, when more sperm fertilize an egg, the developing chick will make it full term before hatching as opposed to eggs with less sperm that are more likely to die during development.  In humans, polyspermy is very uncommon but does occur on occasion.  Many times, in humans, polyspermy leads to the death of the developing baby due to complications during meiosis because of all the extra chromosomes that are made.  It is still unknown why birds have to have more than one sperm fertilize their eggs, but future studies may find a better understanding to explain this.  This is very interesting because of how polyspermy varies from species to species.  If humans were to survive after undergoing polyspermy in utero, how would they look, or function? 

To read the article publised by the New York Times on birds and polyspermy, click HERE