Hummingbirds, with their shimmering plumage and incredibly fast wingbeats, are a source of wonder. During the warmer months, they are a vibrant and active part of Utah’s natural landscape, frequently visiting gardens and natural areas. Their presence is seasonal, marked by annual movements.
Typical Departure Times from Utah
Hummingbirds generally begin their departure from Utah in late summer, typically spanning from late August into early September, marking the peak of their southward migration. While many individuals leave during this window, the timing can vary by species. Rufous hummingbirds often start their journey south as early as July, with many passing through Utah in July and August. Black-chinned and Costa’s hummingbirds typically extend their stay, often departing in September or October. Broad-tailed hummingbirds tend to leave Utah by the end of September, and Calliope hummingbirds usually depart by mid-to-late September.
Departure times are not primarily dictated by dropping temperatures, but rather by significant changes in daylight hours. This decreasing photoperiod serves as an environmental cue, signaling to the birds that it is time to begin their long journey. It is common for adult male hummingbirds to initiate their migration first, with females and younger birds following a few days or weeks later.
Reasons for Hummingbird Migration
As autumn approaches, the flowering plants that provide hummingbirds with nectar begin to die back, and the populations of small insects, which are also a part of their diet, decrease. This reduction in sustenance makes it difficult for these birds, which have incredibly high metabolic rates, to find enough energy to survive.
Decreasing daylight hours act as a crucial environmental cue, triggering hormonal changes within the hummingbirds that prompt their migratory instinct. This innate biological clock tells them when to prepare for their arduous journey. To fuel their long flights, hummingbirds undergo a physiological preparation process, significantly building up fat reserves. They can gain 25-40% of their body weight, and some individuals even manage to double it, storing this fat efficiently in various parts of their body.
Hummingbirds also utilize a state called torpor, a temporary reduction in metabolic rate and body temperature, to conserve energy. In late summer, they strategically employ torpor more frequently, even when they have higher fat levels, to further accumulate the necessary energy stores for their migration. This adaptation allows them to efficiently build the fat reserves needed to power their thousands of miles-long journeys to warmer climates.
Winter Destinations for Utah Hummingbirds
Hummingbirds that breed in Utah typically migrate to warmer regions for the winter, predominantly Mexico and Central America. Some species may also spend the winter in the southern United States. The specific wintering grounds can vary by species, with Rufous hummingbirds often traveling to central and southern Mexico, including mountainous regions like the Trans-Mexican Volcanic Belt, and occasionally further into Central America. Broad-tailed hummingbirds from Utah generally migrate to the highlands of Mexico, extending south into Guatemala. Black-chinned hummingbirds commonly winter in western Mexico, while Calliope hummingbirds also head to Mexico.
They typically undertake this journey alone, relying on their accumulated fat reserves and foraging at stopover points along the way. Upon reaching their winter destinations, they seek areas with consistent food sources, such as year-round flowering plants, and suitable climates that can sustain them until their return north in the spring. High-altitude pine-oak forests and cloud forests are examples of habitats where these birds find reliable nectar and insect supplies during the cooler months.