My sister lives in rural Mille Lacs County and has been getting a lot of cardinals at her feeders lately, but one she photographed looks amazing. It looks to be male on its left side, and female on its right side. It showed up several days in a row with other cardinals, but has not been there the last couple of days. With a little research, it appears it is possible for this to happen in birds when two ovums, fertilized by different males, being to develop then merge together early on. Forbes Article on Male/Female Birds

Very interesting, I had never heard of the "bilateral gynandromorph" before. From what I could gather from googling it, it might have more to do with the chromosome spit as the cell divides, ie resulting in x xyy instead of xx yy.

Thanks for posting this!

I saw both explanations, but the x and xyy scenario doesn’t fit. Sex chromosome aneuploidy in humans is not very rare and results in syndromes such as Klinefelter, XXYY, and Turner, Triple X. These are either male in sex as in the former set of syndromes, or female as in the later.

It seems that in the case of bilateral gynandromorphism, the ovum never truly became a haploid cell during the second meiotic division. It retained its sister chromatid and both sets of chromosomes combined with separate sperms cells which carried different sex determining chromosomes. They never taught anything like this in school. A genuine Joseph-Josephine.

This is fascinating. I am going to share the pictures with my 3rd grade class which is studying birds.

What are the odds? My sister spots and photographs this rare bird, then the next week another one is covered in a national newspaper.

USA Today story of 1/2 males-female cardinal

Jaywalker: "What are the odds? My sister spots and photographs this rare bird, then the next week another one is covered in a national newspaper.


USA Today story of 1/2 males-female cardinal "

Here's yet another article about the same bird, this time from the BBC.

BBC article