Hummingbirds observed across New Mexico during spring and summer are migratory species that journey south for the winter. These tiny, high-energy birds arrive to breed and take advantage of the abundant floral resources of the warmer seasons. Their survival depends on migrating to wintering grounds in Mexico and Central America before cold weather arrives. The timing of their departure depends on the general migration window and the habits of individual species using New Mexico as either a breeding ground or a migratory corridor.
Peak Departure Window
The vast majority of hummingbirds depart from New Mexico during a concentrated period that spans the late summer and early fall. The first signs of the southward movement begin with the departure of adult males, which typically start their journey in mid-to-late July immediately after the breeding season concludes. This early exit allows them to avoid competition with newly fledged young and migrating females.
The peak migration surge occurs throughout August and September when the remaining females and young of the year begin their flight south. During this time, the number of hummingbirds at feeders and flowers can temporarily swell due to the influx of transient birds migrating from further north. By October, most of the local breeding population and southbound transients have moved out of the state. While a few stragglers may occasionally be sighted in November, the general season for hummingbirds in New Mexico is effectively over by early October.
Species-Specific Migration Patterns
New Mexico’s location along a major migratory path means the state hosts several distinct species, each with a slightly different departure schedule. The Broad-tailed and Black-chinned hummingbirds are common summer residents that breed across the state, and their departure follows the general August-September window. The adult males of these species are the earliest to leave, followed by the females and their offspring in subsequent weeks.
The Rufous hummingbird is primarily a transient migrant passing through the state. These birds breed much further north, reaching Alaska and Canada, and follow the Rocky Mountain corridor south on their return journey. Rufous hummingbirds begin appearing in New Mexico as early as July, and their passage can last through August and into September, using the state as a critical refueling stop. Their earlier appearance shifts the migration period forward compared to local breeding birds.
Environmental Triggers for Departure
A hummingbird’s decision to begin its journey south is not based on immediate temperature or an empty feeder, but rather a predictable, internal biological mechanism. The primary signal initiating migratory preparation is the photoperiod: the shortening of daylight hours in late summer. This reduction in light triggers hormonal changes, signaling the bird’s system that it is time to depart, regardless of how warm the weather might still be.
Once the internal clock signals migration, the birds enter hyperphagia, dramatically increasing their feeding to build necessary fuel reserves. They accumulate fat equal to 25 to 40 percent of their body weight, which is stored energy needed to power their long-distance flights. While the primary trigger is the photoperiod, the diminishing availability of natural resources, such as nectar and small insects, provides secondary reinforcement for their departure. This ensures they leave with sufficient energy before local food supplies become scarce.
Managing Feeders During Migration
For individuals who host hummingbirds, the peak migration period requires specific attention to feeder management. The temporary surge in bird numbers means feeders must be kept clean and full, as many transient birds rely on these resources to complete their fat-loading phase. Nectar should be refreshed more frequently than usual, perhaps every one or two days, to prevent fermentation and mold growth, which is harmful to the birds.
A common concern is that leaving feeders up will prevent hummingbirds from migrating, but this idea is not supported by scientific evidence. The birds’ strong migratory instinct, driven by the changing photoperiod, overrides the presence of an easy food source. Keeping a feeder available for at least two weeks after the last sighting is recommended. This ensures that any late-migrating juveniles or later travelers have a source of energy before they continue their solitary journey south.