Hummingbirds are some of the most highly anticipated backyard birds in North America. Knowing when these small birds make their seasonal movements can help backyard birders be prepared to welcome them to and from their yards, gardens, and feeders.
About Hummingbird Migration
Even though hummingbirds are the smallest birds in the world, their migrations can span hundreds or thousands of miles. While there are more than 300 hummingbird species, only a handful of them regularly migrate. Most of the hummingbirds of North America do migrate seasonally between northern breeding grounds and southern wintering grounds. Unlike many birds, however, hummingbirds migrate individually and do not travel in seasonal flocks. They migrate during the day, staying low in the air to watch closely for feeding opportunities, and rest at night.
Backyard birders who have fed hummingbirds for years quickly learn that these flying jewels can be very predictable with their migration patterns. Individual birds often migrate at the same time each year, even arriving and leaving the same yards within just a day or two. But how do they know when it is time to migrate?
When Hummingbirds Migrate
Several factors affect hummingbird migration and when exactly these small birds set forth on their long journeys. The most important factor that determines the timing of hummingbird migration is daylight: the amount of daylight and the angle of the sun relative to the bird's location. As the light levels change seasonally, hummingbirds purposefully eat more, increasing their weight by 25 to 40 percent through hyperphagia, when their hormones change to compel them to gain weight. That extra fat will be valuable energy for their upcoming long flight.
Other factors that influence when hummingbirds migrate include:
- Natural food sources: Hummingbirds will move along their migration routes as food sources appear and disappear. The most important food source is nectar-producing flowers, but the availability of insects is also a factor that can influence when hummingbirds migrate and how fast they travel. This is especially true in spring when abundant insects are a key food source for hummingbird hatchlings to get enough protein for healthy growth.
- Weather patterns: Local storms and strong winds can impact hummingbird migration to a minor degree, delaying the birds' journeys by a day or two. During spring migration, hummingbirds may be caught in bird fallouts. During poor fall weather, migrating hummingbirds may hang out in safe locations for up to a week or two to wait for better traveling conditions.
- Age: Mature birds often start their migration earlier than juvenile birds. Younger hummingbirds take longer to build up their new strength and maturity before setting forth on the long migration journey. Birds that hatched earlier in the year may migrate slightly earlier as well, compared to broods laid later in the breeding season.
- Bird sex: In some hummingbird species, such as the ruby-throated hummingbird, males migrate a few days before females. This gives the male birds time to establish territories so they can successfully court arriving females at the beginning of the breeding season. They follow the same pattern for fall migration to establish winter territories.
- Total migration distance: The further hummingbirds have to migrate, the sooner they start their journey. The rufous hummingbird, for example, has the longest migration of any hummingbird species—traveling between Mexico and Alaska—and may begin migrating long before other hummingbird species are traveling.
In spring, hummingbirds may begin flying north as early as January, taking several months to travel to their breeding grounds and arriving by mid-May at the northernmost parts of their range. In the fall, some species begin migration as early as July, though most hummingbirds don't begin their southward movements until late August or mid-September.
Helping Migrating Hummingbirds
Backyard birders can take several steps to help migrating hummingbirds. It is one of the most common bird feeding myths that feeding hummingbirds will prevent them from migrating. This simply is not true. In fact, savvy birders put their hummingbird feeders up early in the spring and keep them up late in the fall so the birds have a ready food source no matter how local flowers are blooming. Other ways to help migrating hummingbirds include:
- Planting flowers to attract hummingbirds with a natural food source, including both early and late blooming flowers for ample nectar in the spring and fall
- Providing nesting materials during spring migration for breeding hummingbirds to quickly and easily build nests to raise their young
- Taking steps to keep hummingbird nectar from freezing in the late fall so it is still available to late-migrating hummingbirds
- Keeping hummingbird feeders clean and replacing spoiled nectar with fresh sugar water regularly so it will be safe and healthy for hungry hummingbirds
- Supporting conservation initiatives and habitat preservation in hummingbirds' winter grounds so they will have safe territories on both ends of the migration
Knowing when hummingbirds migrate gives birders a migration timeline to anticipate when they will see these beautiful birds, and taking steps to help them will ensure successful migrations for generations of hummingbirds to come.