No study has ever shown that red coloring in nectar attracts them. Adding color to nectar is just an “urban legend”; it’s never been proven to be necessary or helpful. Nowadays, almost all feeders are colorful enough all by themselves. In truth, it’s not just red that attracts them. It’s any bright color except green; (an adaptation that lets them spot nectar-producing flowers in a leafy jungle).
Here in north Texas, microscopic bits of mold (found in most food coloring) can multiply rapidly in heat, ruining an entire batch of nectar and making the birds go elsewhere.
So please keep the nectar fresh and clear, and the Hummingbirds healthy!
We're fortunate, in north Texas. The Central Flyway passes overhead. This
Black-headed Grosbeak &
migration route briefly brings us all sorts of birds that are bound for Canada, upper Midwest, Mississippi valley and so on. In the fall, it brings us birds from those regions, bound for Central and South America.
Each spring and fall we have a good opportunity to see birds native to somewhere else, like these two in the photo. They stop in mid-flight to rest and "gas up" for the next leg of migration. That's IF they spot a safe, vegetated place, and it has the food (seed and insects) they eat, and water to drink and freshen up.
It doesn't matter much how large or small the habitat is - some of the most popular and "bird-friendly" spaces are on lots an eighth of an acre or less. After all, birds have the entire sky to cavort in, in addition to the ground-level habitat.