I’m both an EE and master electrician - DO NOT try to use 240V!!!! Too dangerous......
The problem, as others have said, is not amperage, it is voltage......as others said, get an electric fence power source - or the Bird-b-gone.....they are designed to safely do the trick.
But your wires must be close enough that the birds feet touch both at the same time.
As their foot hide is probably tough, it is likely more an insulator than a conductor, but it should work.
One can run 120v (DO NOT DO THIS) between thumb and finger ONLY if both are very dry, and all you will feel is a slight tickle. This is likely what is happening with the birds.
Wet hands, go from hand to hand so amperage goes through your heart - and the same voltage will kill you quickly.......and obviously - don’t do this either.
About 2 weeks ago, I grabbed ahold of a computer power supply that was shorted and hot.
I knew it was shot but didn’t know it was shorted to the case. Sittin on my kitchen floor, good thing I wasn’t grounded.
Still, the B! slapped me good! Real good!
“One can run 120v (DO NOT DO THIS) between thumb and finger ONLY if both are very dry, and all you will feel is a slight tickle.”
I can confirm that. As a kid, I lived in an old Victorian house where we had a light switch missing the front panel, and old exposed, cloth-insulated wires. One of the wire was completely bare, and my sis and I discovered by accident that if you touched it, you’d get “buzzed”. Nothing really painful, unless you tried to keep touching it in spite of your natural reflex to yank your arm back.