Photo: Facebook.com/Jamie Hill

Alex Bowser

Science/Tech Editor

akb6244@psu.edu

Jamie Hill, a bird watcher who claims to have been bird-watching for 48 years, was able to photograph a bilateral gynandromorph northern cardinal the other day, a rare half-male half-female cardinal.

Hill received word from a neighborhood friend who had an “unusual” bird that frequently came to her bird feeders in Grand Valley, Pennsylvania in Warren County. Their friend informed them that the bird looked as though it were “one-half one species and one-half another.” Hill explains in a Facebook post how the description “piques [his] interest since [he] wasn’t sure if she was referring to a hybrid or a much rarer gynandromorphic bird.”

When they contacted the homeowner, she informed Hill that the bird “had some white on its breast,” making Hill assume that it was leucistic, or had albinistic feathering. They asked if she had photos and if she could provide them some, and when Hill saw the photos, he immediately recognized that it was a rare half-male half-female cardinal.

These unique birds have a functioning ovary on one side of its body, and a functioning single testis on the other side. Hill describes in his Facebook post how “theoretically, this bird could either mate with a normal male cardinal and lay fertile eggs, or it could mate with a normal female cardinal and father her eggs.”

They asked the homeowner if they could come over and bird watch in the hopes of taking some more pictures, and in just one hour, the bird they were looking for came to the feeder. As it perched out in some open trees, Hill was “able to shoot about 50 images” with his photography equipment.

In 2019, just two years ago, another half-male half-female was spotted in Erie, Pennsylvania by a couple, just 60 miles away from the location of Hill’s sighting last week. The couple was able to take some photos as well, which were used in magazines such as National Geographic, New York Times, and many additional birding magazines.

Dr. Daniel Hooper, a postdoctoral fellow at the Cornell Lab of Ornithology explained in the National Geographic article, explained that ”sex determination in birds is a little different than in mammals.”

The sex chromosome determines the gender of the animal, known as chromosomes X and Y. Male mammals have one copy of each of these chromosomes, while females have two copies of the X chromosome. Birds, however, are different. Their sex chromosomes are Z and W, and the females are the ones that have a copy of each chromosome, Z and W, while the males have two copies of the Z chromosome.

This setup by nature can cause some complications, starting with the sex cells’ nuclei. These nuclei usually only have one of either chromosome — males have Z-carrying sperm, and females have either Z or W-carrying eggs. Gynandromorphy occurs when the female egg cell develops with two of these nuclei: one with a Z and the other with a W, which can become double fertilized by two of the Z-carrying sperm.

“They likely occur across all species of birds,” Dr. Hooper states, “but we’re only likely to notice them in species where the adult males and females look distinct from each other.” Cardinals in particular are some of the easiest to distinguish as being male or female, with the males known for their bright red color, and the females identifiable from their light brown feathers.

Hill has also speculated that the bird found in Erie only two years ago could potentially be the same bird as the one he spotted in Grand Valley, as he notes that both birds were female on its left side and male on the right. However, he believes that this is only a possibility and that there’s no solid way to confirm this.