The arrival of hummingbirds brings vibrant color and incredible energy to Michigan landscapes throughout the summer months. These tiny, acrobatic visitors spend the breeding season across the state, captivating onlookers with their speed and aerial maneuvers. As the season turns cooler, this shift prompts an annual, instinctual journey to warmer wintering grounds. Understanding the timing of this exodus is a common interest for those who host these beautiful creatures.
Identifying Michigan’s Common Migrant
The vast majority of hummingbirds seen in Michigan are the Ruby-throated Hummingbird, which is the only species that breeds regularly east of the Mississippi River. This bird, scientifically known as Archilochus colubris, is remarkably small, yet it undertakes a massive migratory flight. They are found throughout the state, from the southern lower peninsula up to the Upper Peninsula. The males are easily identified by their iridescent, fiery red throat patch, while the females and juveniles have a white throat.
Biological Triggers for Departure
The decision to depart is not based on a calendar date or local temperature fluctuation, but rather on deep-seated biological programming. The primary driver for initiating the southward migration is the change in photoperiod, which is the progressively shortening length of daylight hours after the summer solstice. This change in light signals a hormonal shift that prepares the bird for its strenuous journey.
In response to this hormonal cue, the hummingbirds enter a phase of intense feeding known as hyperphagia. They consume vast amounts of nectar and tiny insects to accumulate fat reserves, essentially doubling their body weight from about 3.25 grams up to 6 grams. This stored fat is the exclusive fuel for their long-distance flight, which can include a non-stop, 500-mile crossing over bodies of water like the Gulf of Mexico.
The Typical Departure Window
The fall migration begins in a staggered fashion that spans several weeks across late summer and early autumn. Adult males typically lead the departure, often becoming noticeably absent from feeders and territories by mid-to-late August. These birds have completed their breeding duties and begin their journey first.
The females and recently fledged juveniles follow this first wave, with their peak departure occurring throughout September. Activity at feeders can increase during this time, as the young birds and females are still fueling up for their trip. By the end of September, the bulk of Michigan’s breeding population has departed. A few late travelers may still be observed into the first week or two of October.
Feeder Management During Late Summer
A common misconception is that leaving feeders up too long will prevent hummingbirds from migrating, but this is not scientifically supported. The birds’ instinct to migrate, triggered by photoperiod, is much stronger than the presence of a food source. Continuing to provide nectar does not cause them to delay their departure.
It is recommended to keep feeders refreshed and maintained well after the main migration wave has passed. Leaving feeders up until at least October 1st, or for two weeks after the last sighting, ensures that any late-migrating individuals or those passing through from farther north have a reliable source of energy. This practice offers support to the birds as they complete the most energy-intensive part of their annual cycle.