Two major things involved:
1. Depends where you (bird) is touching, you are prone to get more
pronounced burn at the high voltage part of circuit (coil, antenna). Higher
impedance point - higher voltage - easier, more burn or draw the arc. We
used to light up cigarettes by keying the transmitter, touching with pencil
the "hot" end of the tank coil and drawing the arc, while puffing. W8JI
might argue that current/voltage is ALWAYS THE SAME along the coil, so stand
by for more scientwific 'splanation :-)
Anyone trying above experiment can easily see that it is easier to draw the
arc at high voltage (low current) end of coil than vice versa.

2. Depends on the area/mass (capacitance) of what is touching the RF hot
part of the circuit. Fat person vs. small bird would make a big difference.
If one end of the person is (capacitively) grounded, the more pronounced
effect.

73
--
Yuri Blanarovich, K3BU, VE3BMV



"Frank Alforo" wrote in message
...
If I touch the coil in my tuner while transmitting I get a painful rf
burn.
But a bird can perch on my antenna wire while I transmit 100 watts and it
stays there seemingly without a care in the world. How come?