Husker, I would just go with a 520nm green around 100mw+ without a expander if your in a cold climate.
If your talking a distance of 1/2 a football field away the spot should be wide enough not to hurt them but enough to scare them.
Without putting to much money and wanting to test the laser way of bird control, get a 303 style 532nm DPSS for around $12 that comes with a cheap charger and cheap battery. This will give you a idea, and these 303 do around 60mW's to 80mW's..
If you think its a good way to control them then invest in a better one.
Sanwu is also a good company.
If your talking a distance of 1/2 a football field away the spot should be wide enough not to hurt them but enough to scare them.
Without putting to much money and wanting to test the laser way of bird control, get a 303 style 532nm DPSS for around $12 that comes with a cheap charger and cheap battery. This will give you a idea, and these 303 do around 60mW's to 80mW's..
If you think its a good way to control them then invest in a better one.
Sanwu is also a good company.