A birdbath creates a welcoming puddle for birds to enjoy. Birdbaths present no harm to birds if they are painted with nontoxic paint. However, birds can be poisoned if the baths are painted with toxic paint.
Lead was once widely used as a base in paint. If a birdbath is painted with paint that is lead based, the lead can poison a bird. Birds that suffer lead poisoning may become lethargic and disoriented and fall from their perches in the early stages of lead poisoning. Eventually they lose weight, throw up and experience diarrhea before dying.
Rust preventatives may contain traces of zinc in them. Zinc is another substance that can give birds heavy-metal poisoning. Zinc-poisoning symptoms are similar to lead-poisoning symptoms with the addition of blood in the urine and an inability to fly.
The intensity of the symptoms varies based on how much lead the birds consume. Lead and zinc dust may be carried in water, which means that birds can drink it. Additionally, blue jays have been known to chip paint from structures and eat it to consume limestone found in paint.