Also listened to JV , falconer next door having a cuppa just described trap as a cage trap that was thrown in direction of bird to stop an attack - door somehow trapping only part of the bird- by the sounds of it the falconer removed the bird from trap so description should be fairly accurate.
In America they catch young hawks to hunt for a season, then release them again, they use a small wire box with bait in it, with the box being covered in 100 small loop snares to catch feet- that seems pretty effective- probably goes against the WC Act 1981 though to use in uk