Hummingbirds are recognized for their remarkable migratory journeys between breeding grounds and wintering habitats. Their seasonal presence in Idaho brings a dynamic element to local ecosystems, as they flit among flowers, playing a role in pollination.
Departure Timeline
Hummingbirds typically begin their departure from Idaho in late summer and early fall, from August through September. This migratory movement is a gradual process, not a single, synchronized event. While many leave by mid-September, some individuals, especially juveniles, might linger into early October. The exact timing varies annually, influenced by local weather conditions and food availability.
Migration involves individual birds, not flocks, with adult males often departing earlier than females and younger birds. They journey to wintering grounds, primarily in Mexico and Central America. This departure marks the end of their breeding season in Idaho, as they seek warmer climates and abundant nectar.
Key Migratory Species in Idaho
Idaho hosts several migratory hummingbird species. The Black-chinned Hummingbird is frequently observed at lower elevations and typically migrates south to Mexico for winter. The Calliope Hummingbird, recognized as the smallest long-distance avian migrant globally, breeds in Idaho’s mountainous regions and travels to its wintering areas in southern Mexico.
Rufous Hummingbirds are common summer residents, known for their migration pattern: north along the Pacific Coast in spring, returning south through the Rocky Mountains in late summer. Broad-tailed Hummingbirds are another migratory species, nesting at higher elevations and beginning their southward journey by August. While most hummingbirds migrate, the Anna’s Hummingbird is an exception; some overwinter in Idaho, typically arriving in September and departing by March.
Factors Driving Migration
Hummingbird migration is an instinctual response triggered by environmental and physiological cues. Decreasing daylight hours, known as photoperiod, serve as a fundamental signal for these birds to initiate their journey. This change in light triggers hormonal shifts within their bodies, prompting them to prepare for migration.
Falling temperatures in late summer and early fall also contribute to the migratory impulse, as Idaho winters are too severe for most hummingbird species. The diminishing availability of nectar-producing flowers and insects, which are their primary food sources, signals that it is time to seek more abundant foraging grounds. These environmental shifts compel hummingbirds to build up fat reserves to fuel their long flights, an important adaptation for their survival during migration.
Observing Hummingbirds Before They Depart
To observe hummingbirds before their southward journey, maintain nectar feeders. A solution of one part white sugar to four parts water is suitable; red dye is unnecessary and potentially harmful. Placing feeders in visible locations attracts birds, and multiple feeders can reduce territorial disputes among aggressive species like the Rufous Hummingbird.
Planting late-blooming, nectar-rich flowers in your garden can also support hummingbirds during their pre-migratory feeding period. Species such as bee balm, trumpet vine, salvia, and native columbines are attractive to these birds. Continuing to provide feeders until late September or early October ensures that late migrants, including juveniles, have access to food as they pass through Idaho on their way to wintering grounds.