What is the technique called for repairing a broken feather by using another feather?

The technique of repairing a broken feather by using another feather is known as imping. This method involves taking a replacement feather and fitting it to the damaged quill of the broken feather. The new feather is typically secured with a lightweight material, such as glue or a small dowel, ensuring that the repaired feather can function properly during flight. Imping is an essential skill in falconry and bird rehabilitation, as it helps maintain the bird's ability to fly and thrive in the wild or in training.

Casting refers to the process of a bird regurgitating indigestible parts of its prey, while bating is the action of a bird attempting to fly or escape from its perch. None of these terms relate to the specific technique of feather repair as described in the question.