‘Bio-acoustic’ bird scarers

[B'o'B]

Does anyone have any experiences, good or bad, with these ‘bio-acoustic’ bird scarers for keeping pigeons, rooks, crows, Canada geese and swans off crops.

https://www.scarecrow.eu/scarecrow-180-scarecrow-360/

Thanks

 

[Brisel]

Got a Martin Lishman bird alarm call scarer. Useless thing that issued blood curdling screams nearly as loudly as a gas banger with poor controls for darkness etc. Didn’t do too badly at the bird scaring but like so many other methods, it needs moving regularly or they become immune to it.

 

[B'o'B]

Got a Martin Lishman bird alarm call scarer. Useless thing that issued blood curdling screams nearly as loudly as a gas banger with poor controls for darkness etc. Didn’t do too badly at the bird scaring but like so many other methods, it needs moving regularly or they become immune to it.

I pretty sure that is virtually the same system in a different shape box.
I was thinking of getting one or 2 to move around swapping with bangers to add to the variety of methods. Thanks for the feedback.