the following is an excerpt from a web page.

Feathers can reflect disease in a bird. These feathers are from the same location on the same Peregrine Falcon - one was moulted out prior to contracting West Nile Virus, and the other was dropped shortly after the feather grew in as the bird was recovering from West Nile Virus.

Notice the split in the feather shaft and the malformed shaft near the tip.
Feathers courtesy of Ron Kearney.

The feather on the left was moulted normally prior to contracting West Nile Virus. The feather on the right was dropped shortly after growing in. The feather on the right is substantially shorter than the normal feather and the shaft is warped and twisted.
Feathers courtesy of Ron Kearney.

Another comparison of these two feathers.
Feathers courtesy of Ron Kearney.


so these are some signs of diseases among birds. if you find feathers with these odd charicteristics, DONT PICK THEM UP!!!!