Where do the birds go when it rains?
First of all, birds don’t live in nests. They build nests only when they are ready to raise a family, and the nest is usually abandoned afterwards. (There are exceptions, such as woodpeckers, and often cavity nesting birds like chickadees will roost in their nest cavity at night – esp. during the winter.) Most birds have a home feeding territory. When it rains, they behave kind of like we do, hunkering down more, and sticking closer to the trees. Wet feathers are fine for preening, but make it difficult to fly. If your feeders are under a shelter, the birds may be more inclined to hang out there. I always have half a dozen birds roosting under my patio umbrella in the rain. Some shrubs or trees near the feeder might help, as well. Good luck!