Here in middle Tennessee, we have been getting rain from tropical storm Lee for the past few days.
During this time the hummingbirds feeding at my house seem to flock to the feeders that are in the rain. Anyone know why? I have three feeders and only one is not in the rain. They leave it alone and feed from the ones in the downpour. I have had to refill twice as often during the rain.
Without seeing the specific set-up, it's hard to say, but if the sheltered feeder is near windows, or on a porch where people are often moving about, they may simply be spooked from coming close.
In my experience, the primary reason birds appear to feed more during a storm is that natural food sources are often temporarily unavailable, for a few hours to a few months (depending on the severity of the weather). Even in just a heavy downpour, flowers are likely beaten down and largely inaccessible, and feeders present a much easier-to-access source of food. That is exacerbated in a tropical storm or hurricane in which the flowers (or the vines or branches on which they grow) are ripped down and may take quite some time to replace.
Under normal circumstances hummingbirds get only a portion of their nutritional needs from feeders, and not always from the same group of feeders. I can't count how many times Nancy's handled a hummingbird at a site where the hosts use plain sugar water (as most of our hosts do), and we observed red-dye stained "discharges" from the birds. They often move around over a great distance to feed even when a steady food source is available in one spot. But weather complications can force them to focus their efforts on particular sources.
Baton Rouge, Louisiana