The Rufous Hummingbird (Selasphorus rufus) is a small, feisty hummingbird that breeds in the Pacific Northwest and Canada during the summer before migrating south to spend the winter in the southwestern United States and Mexico. Their migration is one of the longest of any hummingbird species. Many Rufous Hummingbirds travel up to 3,900 miles between their breeding and wintering grounds.
In the Sonoran Desert region of the southwestern U.S. and northwestern Mexico, Rufous Hummingbirds start arriving in July and August for the winter. They take advantage of the desert’s late summer rains that spark blooms of flowering plants that provide nectar. By late September and October, Rufous Hummingbird populations peak in the Sonoran Desert as more individuals arrive from their breeding grounds. The Sonoran Desert provides ideal winter habitat for Rufous Hummingbirds with many flowering plants and relatively mild winters compared to their breeding range.
Detailed Arrival Timeline
The exact timing of when Rufous Hummingbirds arrive in the Sonoran Desert depends on many factors:
Age and Sex
Adult male Rufous Hummingbirds tend to arrive first in the Sonoran Desert, usually in early to mid-July. Adult females and immature birds arrive about 2-3 weeks later from late July through August. The males arrive early to set up breeding territories in advance of the females.
Location
Arrival times can vary across the Sonoran Desert region:
- Southwestern Arizona – first arrivals in mid-July
- Southeastern Arizona – early August arrivals
- Southwestern New Mexico – late July to early August
- Northwestern Mexico – mid-July to early August
Areas farther north and at higher elevations see later first arrival dates.
Weather
Weather patterns each year influence timing. Early monsoon rains in the Sonoran Desert region can spur an earlier start to the bloom of flowers that the hummingbirds depend on. This earlier bloom may cause earlier arrival by the hummingbirds some years.
Breeding Conditions
The success of nesting farther north impacts when the birds will migrate south. If breeding conditions are poor one year, the birds may migrate south sooner. Good breeding success may delay migration south somewhat.
Migration Route to the Sonoran Desert
Rufous Hummingbirds take a circuitous route to reach the Sonoran Desert region each fall:
- Breeding grounds in the Pacific Northwest and Canada (April – July/August)
- Fall migration south through the Rocky Mountains (late July – early September)
- Short stopover in Colorado, Utah, and northern Arizona (August – September)
- Arrival in Sonoran Desert of Arizona/New Mexico/Mexico (July – October)
The birds move quickly based on food availability and weather conditions. Early winter storms may push the birds south faster some years.
Habitat and Food Sources in the Sonoran Desert
Rufous Hummingbirds rely on the following habitat resources and food sources during their Sonoran Desert wintering:
Desert Washes
Desert washes and drainage areas contain essential food plants and trees that bloom in response to monsoon rains in July through September:
- Fairy Duster
- Desert Lavender
- Brittlebush
- Paloverde
- Ironwood
- Catclaw Acacia
Desert Scrub
In scrublands, hummingbirds feed on:
- Chuparosa
- Ocotillo
- Beavertail Cactus
- Hedgehog Cactus
Canyons and Hillsides
Dry slopes contain additional food options:
- Apache Plume
- Penstemon
- Firecracker Penstemon
- Desert Honeysuckle
Backyard Feeders
Up to a quarter of a Rufous Hummingbird’s diet in winter may come from sugar-water feeders provided by homeowners.
Interactions with other Species
Rufous Hummingbirds share the Sonoran Desert in winter with these species:
Anna’s Hummingbird
- Larger and more aggressive – can displace Rufous at feeders
- Rufous males may be subordinate to Anna’s males
- Both prefer nectar from Salvia and other flowers
Costa’s Hummingbird
- Smaller than Rufous – less competitive
- Nest earlier than Rufous, but habitat overlap in desert scrub
- Costa’s prefers Chuparosa, Ocotillo; Rufous prefers Salvia
Insects
- Also feeds on small insects like gnats, aphids, spiders
- Important protein source
- Feeds by hawking insects in flight
Threats and Conservation
Major threats to Rufous Hummingbirds in the Sonoran Desert include:
Habitat Loss
Development reduces scrub habitat and washes preferred by the hummingbirds.
Climate Change
Drying conditions may reduce flowering plants and early blooms.
Window Collisions
The hummingbirds are vulnerable to colliding with windows on homes and buildings.
Predators
Common predators:
- Sharp-shinned Hawks
- Merlin Falcons
Conservation measures to help Rufous Hummingbirds include:
- Planting native flowering species
- Installing sugar-water feeders
- Applying window markings/decals
- Keeping cats indoors
Conclusion
In summary, Rufous Hummingbirds arrive in the Sonoran Desert as early as mid-July, with peak populations in late September and October. Adult males arrive first, followed by females and immature birds. The hummingbirds take advantage of flowering plants that bloom in response to the desert’s monsoon rains. Backyard flower gardens and feeders also provide important food sources over the winter. Conservation of scrub habitat and reducing threats like window collisions and predators will help ensure that the Sonoran Desert continues to provide critical winter refuge for Rufous Hummingbirds.
