I made fresh dinner with a synrad 60w CO2. Fell from the sky ready to eat.....just kidding.
Another approach is a loud bang. Set up something so when the come near it puts off an air horn. Like anything though they do eventual get use to any of this. VAriety is best.
Have the owl animatronic so the head spins around and spits pea soup.
THAT ^^^ REMINDED me- some sounds I read being ones we hardly or never hear- are by nature alaming to animals-- just like the deer warn one another with a 'snort' the make by exhaling thru their noses-- if you imitate that any deer that hears goes 'heads-up' mode(ears and head alerting in 360 ). (I know from caring for a dozen in Fl)
I got a stun/glare/strobe personal device from JL- the Yamataka-
and the snap from the stun feature is loud and very 'sharp' and one we do not normally hear.
-- to test that- I took it to a (24hr) McDs- late nite only one other geek on PC using McDs free wifi== two teenage girls working the counter and chatting a lot etc.
So from under the table I sparked the stun very briefly-AND it 'started' both of them- sayin' 'WHAT was THAT??'
I never looked up...
later 3AM - I was alone there and repeated the experiment and once again they were instantly 'alerted'
later while researching stun guns I saw a video demo-- a lone walker going down a country lane between some falling down buildings & shacks and two loose barking dogs off to one side and another on the right. also barking- but not really advancing much.
the 'walker' then just sparks his stungun and all 3 dogs turned tail and retreated..... he walks on some more and new dog begins to bark- and one zap mage that one back=up.
this guy was never any nearer than ~10 meteds away.
then he turns back--& in a bit a cat comes out of a shack-- the guy snapped his stun-- the cat does a 360 and heads up a smallish tree so fast it ran out of tree and fell!!
Of course-- stunning the birds by hand would work well-- or just that sound. lol jk\
its (the 'Yama') is also a 520 laser ( w/ the 600mW $700)and LED strobe w/ more options than one can learn without some studying and LOTS of practice (in the dark) OR you will shock yourself and trust me it was not pleasant either time!!
___________________
from JL.org
https://www.jetlasers.org/yamataka-series/38-non-lethal-dazzler-laser-500-1000mw-532nm.html#/50-battery-no/49-goggles-no/120-power_levels-532nm_600mw
>>>>>>>>>>
and
https://www.jetlasers.org/yamataka-series/38-non-lethal-dazzler-laser-500-1000mw-532nm.html
And the 'spendy' PHAZERS for birds--
https://www.jetlasers.org/42-bird-phazer-laser-pl-e-pro-series
and more
[URL="https://www.jetlasers.org/42-bird-phazer-laser-pl-e-pro-series"]https://www.jetlasers.org/42-bird-phazer-laser-pl-e-pro-series[/URL]
btw dogs like border collies are good bird chasers too
I still say a plastic owl or two may be the best option..