Raptors hunting on landfills are often exposed to methane flares that singe their feathers. This hawk’s feathers were so badly damaged that he was unable to fly.
One option is to keep the birds until they are completely molted and all the feathers have been replaced with new ones. This can take over a year until they fly again and regain the strength needed to survive.
Another possibility is to attach “feather extensions” to the healthy shaft of the singed feather. This process is called imping in the falconry terminology. We use intact feathers from deceased animals, that match the singed ones in shape and length. The new feathers are glued onto the intact shafts to complete the full plumage. The bird is able to fly right away and can be released much quicker. Those extensions are then shed during the natural molt process and replaced by healthy new ones.
via South Florida Wildlife Center