One thing I would add on gassing for those not so familiar with it, is it should be done slowly*. If an animal is dumped into straight C02 it suffocates as it is still concious and alert and suddenly cannot breath. If the C02 level is increased steadily though it becomes sedated > sleepy > sleep > dead.
It is generally the way to go with birds and mammals, but does need a little thought also. As CaptainRatbag points out birds will generally succumb fast due to the different metabolism also different age/sizes change the rate.
*Slowly not as in hours but usually over a few minutes letting the C02 ratio rise. I only point it out as this is one of the situations where as quickly as possible is not the best, especially for birds which will frighten easily.
** A tub would work well with the sodastream or similar option. (I just have horror visions of some dude trying to connect a peachie to the car exhaust).
It is generally the way to go with birds and mammals, but does need a little thought also. As CaptainRatbag points out birds will generally succumb fast due to the different metabolism also different age/sizes change the rate.
*Slowly not as in hours but usually over a few minutes letting the C02 ratio rise. I only point it out as this is one of the situations where as quickly as possible is not the best, especially for birds which will frighten easily.
** A tub would work well with the sodastream or similar option. (I just have horror visions of some dude trying to connect a peachie to the car exhaust).