Hummingbirds are a cherished sight across Idaho, their iridescent feathers and darting movements bringing life to gardens and natural spaces throughout the warmer months. These tiny, energetic birds are seasonal visitors who undertake remarkable journeys. Their presence signals the arrival of spring and summer, and their eventual departure marks a natural transition as they prepare for migratory flights.
Peak Departure Periods
Most hummingbirds depart Idaho in late summer, primarily August and September. While some early migrants, particularly male Rufous Hummingbirds, may start their southward journey as early as July, the bulk of the population follows later. Black-chinned and Broad-tailed Hummingbirds begin their migration by August, many gone by month’s end. Calliope Hummingbirds, the smallest North American species, also depart around late August to late September.
Some species, like Black-chinned and Rufous Hummingbirds, may linger into October, especially if food sources remain plentiful. Migration timing can vary slightly by species and location within Idaho. Anna’s Hummingbirds are an exception, as some individuals may arrive in October and even remain through the winter, adapting to colder temperatures.
Drivers of Departure
The primary signal for hummingbirds to begin their migration is the decreasing length of daylight hours, known as photoperiod. This environmental cue triggers hormonal changes within the birds, prompting their innate migratory instinct. As days shorten, their bodies prepare for the demanding journey ahead, accumulating fat reserves necessary for sustained flight.
Declining temperatures are another important factor, as Idaho’s winters are too harsh for most hummingbird species. Cold weather directly impacts their survival, especially given their high metabolic rates. Diminishing natural food sources, like nectar-producing flowers and insects, also drive them to warmer climates. This combination of environmental shifts and biological programming guides their timely departure.
Their Journey South
After departing Idaho, most hummingbirds embark on long-distance flights to warmer wintering grounds in Mexico and Central America. Rufous Hummingbirds, for instance, undertake a unique “oval-shaped” migration pattern, traveling north along the Pacific Coast in spring and returning south through the Rocky Mountains in late summer and fall. Black-chinned Hummingbirds often winter along Mexico’s Pacific Coast or in southern Texas.
Broad-tailed Hummingbirds make their way to the highlands of Mexico and as far south as Guatemala, while Calliope Hummingbirds spend their non-breeding season in southwestern Mexico, Guatemala, and Belize. These tiny birds fly during the day, often utilizing tailwinds to conserve energy, and can cover distances up to 23 miles in a single day. Their journey is physically demanding, requiring continuous refueling to maintain their high energy needs.
Supporting Hummingbirds Before They Depart
Idaho residents can support hummingbirds in the weeks leading up to their migration by ensuring readily available food sources. Maintain clean hummingbird feeders with a fresh solution of four parts water to one part sugar; this provides energy for their journey. Continue offering feeders through September, and even into October, to assist late-migrating individuals and transient hummingbirds passing through.
Leaving feeders up does not deter hummingbirds from migrating, as their departure is primarily governed by internal biological clocks and changing photoperiod rather than food availability. In addition to feeders, planting late-blooming flowers offers natural nectar sources, supplementing their diet. Providing these resources helps hummingbirds build fat reserves for completing their demanding migratory flights.