Birds have pretty strong guts, but will poo in a birdbath/bowl because in nature, there’s more water around.
You’re supposed to clean a bird bowl /bath daily. All you really need is a full watering can nearby and a better clean weekly.
Although birds tend to poo almost without thought, as a kid my neighbours had a South African Grey who was let out of his cage daily. He’d be placed on the fire guard over a sheet of newspaper and told “Do It”.
He’d poo and then they knew he was ok to fly around the room without redecoration.