what chemicals prevent mosquitoes from breeding in my bird bath?

what chemicals can prevent mosquitoes from breeding in my large garden bird bath? it is a circle about 3 ft. across. does the chemicals kill the birds that drink out of it?

How can I prevent mosquitos from breeding in a bird bath?

I’m thinking of putting a bird bath in my back yard (so they’ll have water and then my backyard can be a good habitat). I’m worried that mosquitos will breed in the bird bath though (water). I don’t have time to change the water every day..Any tips?

How do you keep mosquitoes from breeding in a garden bird bath?

I have three cement bird baths around my house. The birds make substantial use of them. When rain doesn’t supply the water for them, I do. But someone told me mosquitoes are breeding in these things and I shouldn’t use them. Is this true?