It's spring here in the Northeastern United States, and we're getting a large influx of the wonderful birds who will spend the summer and fall with us. Although we feed and water birds, and any other hungry outdoor creatures, throughout the year, we increase their options during the busier months.
This is also the season when merchants heavily advertise many varieties of birdbaths.
I've read a number of articles saying that birdbaths with moving water are better. They suggest that moving water increases attendance, and keeps the birds, and birdbaths, healthier. For instance, this says
Birds find water sources by sight and sound. Adding movement to your birdbath creates visual and audio cues that birds will hone in on, allowing you to draw more birds to your bath. Properly agitated water can also deter mosquitoes from visiting your bath, as well.
This site also claims that adding motion to water attracts more birds.
Water is essential for birds and while a simple bird bath can provide refreshment, more elaborate arrangements like bird bath fountains have many benefits and can attract more birds to any birder's backyard.
The problem is that most of the sites I found that recommend these devices also sell them.
I'm seeking evidence that birds prefer moving, rather than stagnant, water, from reliable sources that don't make money from their recommendations. It would be even better if they specify which type of water-moving method is preferred.
Anecdotal answers through your own experience are fine too, and would be helpful.
My birds are the American versions, and include swallows (many varieties), sparrows (many varieties), cardinals, blue jays, grackles, robins, crows, finches, thrushes, titmice, woodpeckers, red-winged blackbirds, grosbeaks, mourning doves, canaries, and others in related families.