Picture this: you’re walking down a trail, and a gorgeous feather catches your eye. You stop to look closer, and that’s when you see it–the bottom half of the feather is missing, replaced with a shredded shaft, a weird bluish tube, or just a bloody pulp. What happened? And how are you supposed to identify this bottomless feather?
Bottomless feathers are a fairly regular phenomenon. The lack of a bottom can mean any number of things for the story of that feather, but I’ve found these two to be the most common:
A sheared feather, or a feather with a straight cut across the shaft, could indicate that a mammalian predator (i.e. fox, coyote, dog) ate and removed the feathers from a bird by gnawing them off.
A feather with a pinched section at the bottom, possibly encased in a bluish liquid-filled tube, was still growing when it was removed from the bird’s body. These are called pin feathers and are usually associated with juveniles or adult birds that are regrowing feathers. Pin feathers are not naturally molted and often indicate an attack or a disease (ex: psittacine beak and feather disease, pterotillomania) when found off the living bird.
You could conceivably find a pin feather that is also sheared.
Bottomless feathers complicate the identification process in a few ways–depending on how much of the feather is missing or undeveloped, the downy base of the feather might not be available, so the texture (or its visual cousin, microscopy) of the down cannot be analyzed.
Size matters when it comes to feather ID, and can sometimes be the only reliable way to tell apart feathers from species with similar colors or patterns. Without the full length of the feather, you may have to use a different measuring interval when comparing your feather to reference specimens.
It is necessary to pay closer attention to the remaining traits, like color, pattern, shape, location found, et cetera. Not to say that bottomless feather identification is impossible–this Turkey Vulture primary that I found in Georgia is just one example of a severely truncated feather that made it to a species-level identification because enough distinctive traits remained:
So here’s hoping that you learned something new, and that you’re better prepared for the next time you come across a bottomless feather.
P.S.: Bottomless feather identification is probably better for you than bottomless fries. Just sayin’ 😉
P.P.S.: I wrote an entire blog post about “bottomless feather identification” to make a mediocre pun. I hope you enjoyed.