Question about a weird feather

[CheekyMama]

Hey, everyone. It's been a while!

I have a question about a weird feather I saw on Cheeky. Have you ever seen one of these before, and what the heck is it? I can't get a great shot of it because of the lighting, but I hope you can see what I mean.

CM

 

[Bobioden]

That is not a feather, it is his preening gland. They use this to get fluid to preen themselves.

 

[CheekyMama]

I suppose I should have done my research first, but I wasn't sure how to phrase it in Google. Thanks!