Very interesting question. I think there is no easy answer, though. Sometimes I noticed that molting birds didn't seem to feel well, sometimes I haven't noticed any signs of discomfort. I'm wondering how to classify it if they have parasites such as mites and lose part of their plumage. I'm very interested what ornithologists have to say about this.
I think I have read that molting is very uncomfortable because the feather sheaths are stiff when they emerge. I think it's also physically taxing for the birds so they need to rest and eat as much as they can so have their strength when they're ready to move one.
I'm not an ornithologist, but having had parrots for many years, I know that molting requires extra energy and can be uncomfortable. Incoming feathers are blood-filled and very sensitive to the touch; I think it hurts if there is pressure to the point of emergence. Our larger birds appear to be more stressed than the smaller ones; the macaw especially is much moodier and less willing to be touched, squawks and threatens to bite if a senstivie area is touched. As the new sheath-covered feather grows, the blood dries from the outer end and the sheath becomes brittle and begins to deteriorate. The birds use their beaks to remove the ends as they dry out - if they are mated, the mate may help, which promotes bonding. A pet bird appreciates being "preened" by its humans at this point. On large feathers such as tail feathers or large wing feathers on a macaw, that sheath is very tough and it takes quite a while to grow a large feather like that & shed the sheath. At some point, a feather no longer has blood in it, but previous to that, I've read that if such a feather breaks, a bird can actually bleed to death. Ornithologists, correct me if I've made any misstatements!!
Sounds good Anita, and great question John! A lot of work on bird genetics has been done over the past 20-30 years looking at everything from the relatedness of individuals to species relationships. In these studies, one field technique is to collect a "blood feather" which is a new feather that is growing in. As Anita says they have a blood supply and one would assume are innervated as well. Bird blood contains DNA and that is what is used for the genetic analysis. When you collect a blood feather as I have done in the past, you have the distinct impression that the bird feels it. By the way collections such as this have to go through animal care committees and are done by trained individuals.
Whether the emergence of a blood feather during the process of moulting causes pain or not is I think an open question. Just because the feather has a nerve connection does not necessarily mean that it's normal production causes pain. Pain is a product of evolution and is designed to signal the brain that something potentially or actually damaging to the body is occurring so that avoidance behaviour is called for. During the normal process of moulting, it may not make evolutionary sense to to be telling bird brain that something is wrong. However, I've seen penguins moulting and I agree that from a human point of view they look decidedly unhappy about it.
Moulting takes a lot of energy and protein and is very taxing on the individual bird. Studies have shown that it is the most costly thing a bird does over the course of the annual cycle and so is more costly than migrating and breeding, which is impressive when you think about it. Many birds cannot breed and moult at the same time so moult tends to take place on its own at specific times of year.
Last edited by John Chardine; 08-03-2008 at 03:45 PM.
Thank you all for the excellent feedback. Interesting idea that pain may not occur with normal bodily changes such as molting. But makes sense. After all, we also don't feel pain when our bodies grow during puberty. Well, maybe in a different way... :)
Does molting hurt?
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