A new feather still growing from the follicle, containing a blood supply in the shaft (visible as a dark blue or red line). Cutting a blood feather causes profuse bleeding and significant pain.
Critical safety knowledge for any bird wing or nail trim. Blood feathers are common during molting season.
If a blood feather is accidentally cut, apply cornstarch or styptic powder with gentle pressure for 30 seconds. Do not pull the feather unless bleeding won't stop.