Feeders full, trees buzzing with song, yet your stone bird bath sits eerily quiet while only the odd pigeon takes a sip. If you are hoping for flashes of yellow and red from European goldfinches or the bright caps of blue tits, one tiny detail could be stopping them. The ideal bird bath depth for goldfinches and blue titsFor small UK garden birds, the sweet spot is a shallow 2cm of water around the rim. That depth lets blue tits, goldfinches and robins stand comfortably, fluff their feathers and bathe without losing their footing. Once blue tits and goldfinches realise your bath is shallow, safe and constantly refreshed, they tend to return day after day.