Feather Identification Tips, Leucism

Unusual Blue Jay feathers: part one

Earlier this week, I came across a very interesting Blue Jay specimen while doing a presentation at the Delaware Museum of Natural History. These presentations usually entail me choosing several of the awesome specimens in the education collection (i.e. toucan bills, pheasant tails, and owl wings) and then pointing out their unique traits and adaptations. This Blue Jay study skin is just one of many in the collection.

Like several other specimens in the museum’s education collection, this Blue Jay was missing its tag, so no more information about it was available than what could be gleaned from its physical appearance–no finding location, date, or age, for example.

Anyways, the first thing I noticed about this jay was the white rump. I couldn’t remember having ever seen that coloration on a Blue Jay, so I figured that this individual had leucism (partial albinism) at that spot and left it at that. Little did I know that there was something even more curious just below the surface…

At some point, I noticed that the wing feathers were rather disheveled, either from the day’s activity or poor storage, so I decided to go through each of the individual wing feathers to preen them back in shape. As I made my way through, I started realizing that some of the secondaries (inner wing feathers) had an abnormal amount of white patterning, just like the rump:

Weird, huh?

Now, Blue Jay wing feathers do typically have white patches on the tips of their secondaries and the bases of their primaries, as seen in this group of Blue Jay feathers (from a single individual) that I found in Georgia:

However, never before had I seen secondaries with both a white tip and base, let alone a base patch so large that it actually connected to the white tip. I checked out the specimens on Featherbase and The Feather Atlas to increase my sample size, and not one of them exhibited anything like this either.

The other wing has a symmetrical pattern, which makes this oddity even more interesting.

The leucism I observed in the rump feathers likely caused the abnormal secondary pattern too. Leucism’s causes range from genetic mutation, malnutrition, lack of solely food-derived pigments, and damaged feather follicles due to injury.

Since the pigment that’s missing on these jay feathers is melanin (which controls black and brown), lack of solely food-derived pigments can be ruled out right away because birds can produce their own melanin and do not necessarily derive it from their diet. I would also rule out damaged feather follicles because it seems unlikely that any bird would be injured at the same exact location on both wings.

I think that a genetic mutation or overall malnutrition would be the most likely causes here. Perhaps one or both of its parents carried and/or expressed a leucism gene, or this bird or the bird’s ability to make melanin became somehow inhibited as it grew in its secondaries and rump feathers–this last explanation makes the most sense to me because most adult birds replace their feathers in a specific, symmetrical sequence, one after the other mirrored on both wings. If such a melanin-inhibiting event began while a corresponding pair of feathers grew in, and ended after a few more sequential pairs grew in, it would explain why the pattern is on both wings and in a group of adjacent feathers. Of course, this assumes that this was at least a second-year bird. Juveniles (first-year birds) grow all of their feathers in at the same time, so a melanin-inhibiting event would have impacted every single feather on the bird.

Of course, that’s all just speculation on my part. All I can say with certainty is that this Blue Jay has an unusual lack of pigment that looks really beautiful, at least in my opinion.

The leucistic secondaries aren’t the only interesting thing about this bird, actually. The feet have several tiny, yellow feathers stuck to them. While it’s difficult to positively identify small songbird feathers, I would guess that they’re goldfinch or warbler feathers. The real mystery here is how they got there, and without an information tag or background on this specimen’s preparation, that’s even farther outside my solving abilities than the whole leucism thing. Most likely, though, this happened due to poor storage. Prepared bird specimens commonly retain a lot of “grease” in their feet, which soft materials like feathers easily get stuck to.

If there’s a lesson to be learned here, it’s that individual birds and their feathers often have their own stories to tell, even after death. This is part of the reason why museum collections are so important–they record these stories for years, even centuries for future bird enthusiasts and researchers to interpret.

Check out the part two of this post!

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