Well the bird bath I have is all concrete and had to use a dolly to move the sucker. HEAVY!!!! Anyway, I put it amongest the
roses...WATCH OUT LITTLE BIRDIES!!!! When the
roses were cut back it was okay...the birds could see the cats coming...but now that the bushes are full the cats can sneak up on them. NOT GOOD!!! Have heard to put bird baths in an open environment just for that reason. I don't know about the gravel...I personally wouldn't put any in. I clean mine out every time I fill with water. I like clean fresh water to drink so I do the same for the birds. With the gravel it would make cleaning much harder. Oh, I also have mine in the sun...guess that was clear when I said they were amongest the
roses. Anyways...don't know if this helped and others will have different opinions. Have a great day.
Catlover