Earl doesn't sugarcoat it. "People buy a pretty bowl, stick it in the yard and think they've done something good. But a lot of bird baths out there aren't built with birds in mind – some can actually cause real problems."
What he's observed over 40+ years:
Too-smooth surfaces – Ceramic, plastic, glazed stone. "Birds can't grip it. Their feet slip. They either avoid the bath entirely – or they fall in and can't get out."
Too deep, no graduated edge – "Fledglings and small birds like wrens need shallow water. If the bowl is the same depth all the way across, small birds can fall in and drown. I've seen it happen."
No insect escape route – "Bees, butterflies, hummingbird moths – they all drink too. But if they land on a smooth rim and slip in, they can't climb back out. I've opened bird baths with dozens of dead bees floating in them."
Cheap materials – "Plastic heats up in the sun and leaches chemicals into the water. Thin metal rusts after one season. Cheap ceramic cracks in the first hard freeze."
Standing water becomes a breeding ground – "If you don't clean a bird bath regularly, bacteria and parasites build up fast. Mosquito larvae, algae, you name it. And most store-bought baths are shaped in a way that makes them nearly impossible to scrub clean."
"Folks mean well. But without the right knowledge, they can do more harm than good."