On Countryfile on the BBC today, there was a guy with a cat scarer, which
looked like a small torch.
You point this at the cat, or whatever presumably, to chase it away by
pressing the button, it works with ultrasonic frequencies. I have searched
for this with no success; but there are plenty of PIR operated units
available. Anyone have any knowledge of a source?

The Countryfile programme was partly about the declining birdlife, partly
blamed on feral cats and grey squirrels.

Jaymack