Results of my brief investigation:

Part 1 - The search for sources

This is the only Japanese source I found, though as I don't speak Japanese, that may be on me. ~~The article claims it was announced in a Twitter post from the zoo, but I also do not use The Everything App, so I can't verify that.~~ I did verify The Mainichi is a legit news source.

I did locate the original post on X, The Everything App. Here is the original and a quick browser translation:

So, after finding the zoo's post, I believe this more than when it was just mainly social media reposts. But what does this mean for our little owl friend here?

Part 2 - Birds care not for mammalian genetic rules

This week has given me some great examples of how we feel we understand animals, but most of us know nothing about them, and how alien from us they really are, in a birds vs mammals sense anyway.

Yesterday I learned avian red blood cells have nuclei. I read a little bit about it, but most goes over my head. There are a number of hypotheses about the advantages/disadvantages of nucleated vs enucleated cells, but it sounds like there is not enough collected and studied data for us to understand the how and why yet.

Now today, reading about how this owl could fool the DNA test, there are many ways since the moment of conception that our bodies don't function in many of the same ways whatsoever.

Human chromosome pairs are normally pairs XX for female and XY for male. Avian chromosomes are ZW for female and ZZ for male. That's not so surprising we have different sized and differently functioning chromosomes as we're really different than birds, but here is the crazy part. Time to check out the moment of conception.

In humans, 2 sperm can fertilize a single egg. Normally, that results in a nonviable pregnancy, as the way mammalian genetics and cell division works, it just causes too many genetic errors. It is thought that about 1% of human pregnancies involve polyspermy. There are only 2 documents cases (case 1, case 2) of viable human pregnancies, resulting in semi-identical twins, that can be either the same or different genders while coming from the same egg and sharing a single placenta.

Part 3 - Gynandromorphs

From my really basic understanding of what is going on, mammalian cells have their functions determined by the presence of hormones. Even with conflicting genetic information, cells will express themselves based on the sex determinative hormones they are surrounded by. Indeterminate sex expression is basically suppressed by the prevailing hormones.

From what science currently understands, bird cells do not adapt to hormones the way mammalian ones do. This leaves the original cell to replicate with both genetic pairs, replicating both chromosome pair without issue. This has been documented in numerous bird and insect species, along with some other animals, and the resulting organism is called a gynandromorph.

Gynandromorphs can be male/female hybrids with functioning body parts and gene expressions of both sexes. This can even result in bilateral gynandromorphism, where the organism is exactly what you would imagine a male and female slapped together would look like.

Here are some examples of bilaterally gynandromorph animals, where inside and out, they are half male, half female.

Coloration of both sexes is present and both sexes' reproductive organs can be present.

Part 4 - So what about this dang owl already?!

Is the owl in question a gynandromorph? It doesn't look like it. Barn owl males and females look similar but have some potential differences in size and plumage, but I don't see the belly spots or neck beard coloration at all. It may just be the angle of the photo.

It may be as simple as an error in the test. Avian DNA testing is claimed to be 99.9% accurate. Maybe this is the 0.1%. Perhaps a sample got swapped or contaminated. With the sparse info available, we may not know.

This may have been a very long post to say, "eh, I dunno," but I certainly learned a ton following up on this! I hope you enjoyed it. Don't quote me on anything here, as I'm no biologist or geneticist, but I don't think I interpreted anything too incorrectly.

Check out this article, or this one, or the gyandromorphism wiki for more!