It is a very common myth is that keeping hummingbird feeders up too long will stop hummingbirds from migrating. This is simply not true! Hummingbirds have an instinctive urge to migrate and this is not based on whether feeders are up or not. When migration occurs is determined by a change in the length of the day or photoperiod. It is quite common for hummingbirds to begin their migration journey when there are still plenty of flowers and feeders available. Male hummingbirds often begin their migration journey two weeks before the female does so. It will depend on the species as to when they choose to begin their migration.