Hummingbirds typically begin their departure from Iowa in late August, with the majority of the population having migrated south by mid-September. While some individual birds, particularly juveniles or late nesters, may linger into early October, especially in southern Iowa, the peak migration period for these tiny marvels concludes by the end of September. Their departure is a natural response to changing daylight hours and diminishing food sources as cooler weather approaches.
Understanding Hummingbird Migration from Iowa
The primary hummingbird species found in Iowa during the breeding season is the Ruby-throated Hummingbird (Archilochus colubris). These birds spend their summers across the eastern and central United States, including all of Iowa, before embarking on an incredible journey to their wintering grounds in Mexico and Central America. Their migration is a remarkable feat of endurance, often involving a non-stop flight across the Gulf of Mexico.
Their departure from Iowa is not triggered by the first frost, but rather by an internal biological clock influenced by photoperiod—the shortening of daylight hours. This instinct prompts them to begin building up fat reserves in late summer, essential fuel for their long journey. As days grow shorter and temperatures begin to dip, their natural inclination is to head south where food remains abundant year-round.
Iowa’s Role in the Hummingbird Life Cycle
Iowa serves as a crucial summer breeding ground for Ruby-throated Hummingbirds. The state’s diverse landscape, from its rolling hills and river valleys to its numerous parks and suburban gardens, provides ample nectar-producing flowers and insect populations necessary for raising their young. Female hummingbirds typically build tiny, cup-shaped nests in deciduous trees, often camouflaged with lichen and spider silk.
During late summer, Iowa’s abundant flora, including jewelweed, cardinal flower, and various garden annuals, provides critical energy for adult hummingbirds and their fledglings. The state’s position in the central flyway means it experiences a significant passage of these birds as they move south, making late August and early September an exciting time for birdwatchers across Iowa.
Preparing for Their Departure: Practical Tips for Iowa Residents
As hummingbirds prepare to leave Iowa, residents can take several steps to assist them:
- Maintain Feeders: Continue to keep hummingbird feeders clean and filled with a fresh solution of sugar water (one part sugar to four parts water) through September, and even into early October. This provides a vital energy source for migrating birds.
- Plant Late-Blooming Flowers: Incorporate late-blooming, nectar-rich flowers into your garden, such as salvias, fuchsias, and zinnias. These plants offer natural food sources as other flowers fade.
- Don’t Remove Feeders Too Early: There’s a common misconception that leaving feeders up will prevent hummingbirds from migrating. This is false. Their migration is driven by instinct and daylight, not by the presence of food. Leaving feeders up can provide essential fuel for late migrants or stragglers who might still be passing through.
- Monitor Activity: Pay attention to the decreasing numbers of hummingbirds at your feeders. This is a good indicator that the bulk of the population has moved on. You can typically take down feeders once you haven’t seen a hummingbird for about two weeks, usually by mid-October in most parts of Iowa.
Safety Notes for Hummingbird Feeders
When maintaining hummingbird feeders, always prioritize the birds’ health:
- Avoid Red Dye: Never use red dye in your sugar water solution. It is unnecessary and potentially harmful to the birds. The red color of the feeder itself is sufficient to attract them.
- Clean Regularly: Clean feeders every 2-3 days, especially in warm weather, to prevent the growth of mold and bacteria, which can be fatal to hummingbirds. Use hot water and a bottle brush; a weak vinegar solution can help with stubborn residue, but rinse thoroughly.
- Placement: Place feeders in a shaded area to keep the nectar fresh longer and prevent fermentation.
Frequently Asked Questions
Q: What kind of hummingbirds are typically found in Iowa?
A: The Ruby-throated Hummingbird is the most common and widespread species found in Iowa during the breeding season and migration.
Q: Do hummingbirds migrate alone or in groups?
A: Hummingbirds are solitary birds and typically migrate alone, though they may follow similar routes.
Q: When do hummingbirds arrive in Iowa?
A: Ruby-throated Hummingbirds generally begin arriving in Iowa in late April to early May, with peak arrivals throughout May.
Q: Does leaving feeders up prevent hummingbirds from migrating?
A: No, leaving feeders up does not prevent hummingbirds from migrating. Their departure is driven by instinct and changes in daylight hours, not by the availability of food. Feeders can provide crucial energy for migrating birds.
Conclusion
Hummingbirds begin their southward migration from Iowa in late August, with most having departed by mid-September. This annual journey is a testament to their incredible resilience and the powerful instincts that guide them to warmer climates. By understanding their migration patterns and offering continued support with feeders and late-blooming flowers, Iowa residents can play a vital role in the successful passage of these tiny, vibrant birds.
