Herself once asked our vet why our cats preferred puddle to any water we put in their drinking bowl. It's not enough to poison humans, but They dump chlorine in piped water to stop fungal growth and suchlike in the pipes; in summer, there's enough that even I can smell it. Cats' noses are much more sensitive ....

Give it a few days for the traces of chlorine (and vinegar) to dissipate, SRS, and methinks the birds will be back.