The Ruby-throated Hummingbird is the primary species that breeds across the eastern United States. These tiny birds spend their summers in Mississippi, raising their young before embarking on a long southward migration. Understanding when and why they depart is a source of frequent curiosity for residents who host them at feeders and in gardens. This article details the timing of this southbound journey from Mississippi and explains the biological mechanisms that drive it.
The Primary Departure Window
The peak departure period for Ruby-throated Hummingbirds in Mississippi spans from late August through mid-October. Migration is a staggered departure based on the bird’s age and sex, not a single mass exodus. Adult males, having completed breeding duties, are the first to leave, moving south as early as late July or early August.
Adult females, who are responsible for raising the last brood, follow several weeks later, usually departing throughout September. The final group to leave is the season’s juveniles, who begin their first solo migration in late September and early October. While the majority of the population has moved out by the second week of October, migrants from farther north continue to pass through Mississippi until the end of the month.
The Biological Drive for Migration
The primary trigger for fall migration is the shortening of daylight hours, a phenomenon known as photoperiodism. This change cues an internal hormonal response, signaling the hummingbirds to build up fat reserves and prepare for the flight south. The timing is governed by this biological cue; the birds do not wait for cold weather or dwindling food supplies.
To fuel their trip, the birds enter hyperphagia, or increased feeding, allowing them to gain 25 to 40% of their body weight in fat before departure. Most Ruby-throated Hummingbirds leaving Mississippi head toward the coasts of Louisiana and Texas. From there, they prepare for a non-stop, 500-mile flight across the Gulf of Mexico to their overwintering grounds in Mexico and Central America.
Feeder Management and Timing
A misconception is that leaving hummingbird feeders up will delay the migration of Ruby-throated Hummingbirds. This is not supported by scientific observation, as the birds’ departure is triggered by photoperiod, not food scarcity. Maintaining feeders provides a necessary energy source for both resident and transient migrants, especially those passing through Mississippi from northern states and Canada.
Residents should continue to maintain their feeder presence through October. During this period of heavy usage, it is important to clean the feeders every few days, as warm temperatures can cause the sugar water to spoil quickly. Using a simple 4:1 ratio of water to white cane sugar provides the appropriate fuel without the need for commercial coloring or additives.
Late Season Sightings and Winter Residents
While the main migration of the Ruby-throated species is complete by early November, sightings of hummingbirds in Mississippi during the late fall and winter are not uncommon. These late-season birds are typically not Ruby-throats, but western species that have taken an unusual migratory path. The most frequently observed winter visitors include the Rufous, Black-chinned, and Calliope Hummingbirds.
These individuals sometimes overwinter along the Gulf Coast and rely on supplemental feeding to survive colder months. If a hummingbird is still visiting a feeder in November, keep the feeder clean and filled, especially during freezing weather. Enthusiasts who encounter these rare winter visitors are encouraged to report sightings to local birding groups or licensed banders, who monitor these unusual migration patterns.