I agree with the poster saying they are after the moisture. They leaves might taste good also. I've seen various birds, including finches, drink from my hummingbird feeders. Sadly, the first year I noticed my sedum looking bedraggled I sprayed them for bugs. I felt so bad afterwards when I saw that it was the birds, not bugs. Your plants will come back. They won't harm it. Just enjoy them. I call it my bird bush.