Which of the following is not necessary for a newly trapped bird?

A transmitter is not necessary for a newly trapped bird because its primary purpose is to track the bird's movements once it has been released and is flying free. New falconers typically focus on establishing a bond with their bird, ensuring it is comfortable and acclimated, before potentially introducing tracking equipment.

In contrast, a glove is essential for safely handling the bird, as it protects the falconer from the bird's talons and provides a stable surface for the bird to perch on. A swivel is important to prevent the telemetry or leash from twisting and potentially injuring the bird. A leash is also crucial as it allows the falconer to control the bird while it is being trained and helps prevent escape. Each of these items serves a specific function in the early stages of working with a newly trapped bird, while a transmitter is more relevant for later stages of tracking the bird in flight.