I used this type of carrier to transport pigeons as well as chickens when when needed. I have a few or these in different sizes also.
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If you decide to build a release cage, here is a suggestion (about cages) that some racers used to use.
Cage was made so top half would be completely lifted off, or hinged so when opened, the bottom half allowed all birds to fly up at same time.
That was the type they used for releasing pigeons for races.
You can do the same with the above carrier, by unsnapping the latches, and lifting off the top portion. I know there are also some screws that the edge has. Only needed there when the load, like a heavier dog, or cat would be the transported passenger.
I would just open the wire doorfront , and tap on the back portion of cage to give everyone the notice. Time to go.......