Most birds aren’t overly fussy about the type of bird bath they use, as long as it’s appropriately sized and filled with clean water. One factor that determines whether birds will use your bird bath is whether it's deep enough for them to comfortably bathe—1 to 3 inches is the optimal depth for most birds. Additionally, some large birds prefer not to use hanging bird baths, which can move around when they land on the edge.  "Smaller birds like songbirds like shallow baths, so try to keep the bath no more than two inches deep in the center. You should add pebbles or rocks that break the surface of the water –that’ll help the birds gauge how deep the water is and give them something to perch on in the basin," says Rowden. "Installing a mister may attract hummingbirds, who will fly through the vapor or bathe on nearby dripping leaves."