Luckily I've only had to do this once so far, but I went with the "gas chamber" method 
I just couldn't bring myself to physically cull the bird and see the blood and so on and so forth. As long as you have plenty of fumes in the box it makes for a quick and quiet kill. The one I did just went to sleep and didn't wake up, no flailing around or blood or anything like that. For me it's the most humane because it's the only one I can carry out

I just couldn't bring myself to physically cull the bird and see the blood and so on and so forth. As long as you have plenty of fumes in the box it makes for a quick and quiet kill. The one I did just went to sleep and didn't wake up, no flailing around or blood or anything like that. For me it's the most humane because it's the only one I can carry out

@aart do you have another one?
That's certainly a method worth considering! I've heard of lots of people trying to asphyxiate birds with CO or CO2... But I almost asphyxiated in a airtight bivy on a cold night once. It was one of the most terrifying experiences I've been through! I wouldn't want to do that to any other living thing. Ether is a much better idea!
