Will Sikaflex Concrete Fix harm birds if it is used to repair cracks in a concrete bird bath and will it cure to a hard finish?

No, Sikaflex Concrete Fix will not harm animals after the product has reached a full cure. Please allow 5 to 7 days for the sealant to fully cure before proceeding with your project. The cracks must be a minimum of 1/4 inch x 1/4 inch. Sikaflex Concrete Fix remains flexible to allow for movement and cures to a flexible, elastic finish.