Hummingbird migration is a phenomenon that fascinates bird enthusiasts and nature lovers alike. Every year, these tiny birds make an incredible journey, traveling thousands of miles between their summer breeding grounds in North America and their winter homes in Central America and Mexico.
The timing of hummingbird migration depends on a number of factors, including weather and food availability. Generally, the migration begins in late summer and continues into early fall as hummingbirds retreat from northern areas ahead of winter. However, the exact timing can vary significantly from year to year.
So when exactly does hummingbird migration start? Has it begun yet this year? Let’s take a closer look at what’s involved in hummingbird migration and the telltale signs that it’s underway.
What Triggers Hummingbird Migration?
Hummingbirds migrate in response to certain environmental cues that signal it’s time to travel south. Here are some of the key factors that trigger hummingbird migration each year:
Day Length
Like many birds, hummingbirds primarily use changes in day length as their cue to begin migrating south. As days get shorter in late summer, hummingbirds instinctively know that cold weather and meager food supplies are around the corner. This prompts them to start their southerly journey.
Food Availability
Abundant food sources are critical for hummingbirds, as they have very high metabolisms and need to eat frequently. The availability of nectar-producing flowers plays a major role in migration timing. As blossoms begin to fade and die off in fall, hummingbirds take it as a sign to migrate south where nectar is still plentiful.
Temperature Changes
Hummingbirds are highly sensitive to drops in temperature as they lack the insulation required to survive freezing conditions. If cold snaps occur early in fall, it can spur large numbers of hummingbirds to take off on migration ahead of schedule.
Instinct
Research shows hummingbirds rely heavily on instinct to navigate their biannual migration. Even first-year juvenile birds with no prior experience are able to find their way between seasonal ranges up to 3000 miles apart. This suggests migration patterns are innate within hummingbird species.
What is the Hummingbird Migration Route?
Hummingbirds follow established migration routes known as flyways when traveling between their summer and winter grounds each year. Here is an overview of the hummingbird migration route:
Western Flyway
– Covers the western half of North America
– Follows the Pacific Coast and Colorado River
– Major stopover sites in California and the Southwest
– Ends in Mexico and Central America
Eastern Flyway
– Covers the eastern half of North America
– Follows the Gulf Coast and Atlantic seaboard
– Stopovers along the Gulf states and Caribbean islands
– Also terminates in Mexico and Central America
Crossings
– Some hummingbirds cross the Gulf of Mexico, a 500+ mile open water flight
– Ruby-throated hummingbirds are especially known for trans-gulf crossings
– Others opt to follow coastlines and avoid large water crossings
Regardless of their route, most hummingbirds complete their fall migration by November and settle into winter homes by December or January.
What are the Stages of Hummingbird Migration?
Hummingbird migration does not occur in one epic flight from north to south. Instead, it happens in a series of stages:
Stage 1 – Southbound Migration
– Begins in late summer as birds depart breeding grounds
– Hummingbirds fly solo and only travel during daylight
– Make frequent stops to rest and refuel along the flyway
– Can cover 20-40 miles per day at this stage
Stage 2 – Stopovers
– Major stopover sites located along migration routes
– Provide food, shelter, and safety for resting birds
– Some remain for days or weeks to build fat reserves
– Key stopovers include southwest desert oases and Gulf/Atlantic coasts
Stage 3 – Trans-Gulf Crossings
– Most challenging part of fall migration for many hummingbirds
– Involves flying 500+ miles nonstop over open ocean
– Done in a single overnight flight to maximize fuel efficiency
– Not all hummingbirds perform trans-gulf crossings
Stage 4 – Arrival on Winter Grounds
– Final push to reach winter nesting areas in Mexico/Central America
– Ruby-throats are one of the farthest traveling species
– Migration completes by November or December
– Remain in winter grounds until spring return migration
This multi-stage migration allows hummingbirds to complete their long journeys despite their small size and high metabolic rates. Stopovers provide much needed rest and refueling opportunities.
What are Signs that Hummingbird Migration has Started?
Determining when hummingbirds begin migrating each fall can be tricky. Here are some clues that hummingbird migration is underway in your area:
Earlier Activity and Feeding
Hummingbirds need to pack on weight before a long migration flight. You may notice them up and active earlier in the day and feeding more aggressively as they try to meet higher energy needs.
Greater Aggression
Competing for food resources becomes more intense leading up to migration. Dominant birds may chase others away from feeders more often.
Disppearance of Males/Juveniles
Adult male hummingbirds and juveniles depart breeding grounds first. If these birds suddenly disappear from your feeders, it likely signals the start of migration.
Arrival of Migrants
You may notice new hummingbirds visiting your feeders that do not reside in your area and are just passing through on migration. In eastern states, sightings of western species are a good indicator of migration activity.
Rapid Weight Gain
Hummingbirds preparing for a long migration flight will gorge themselves, sometimes even doubling their body weight before departure. Noticeably fatter birds at feeders often precede a mass exodus.
Restlessness
Pre-migration urge to move on causes some hummingbirds to appear restless, spending less time at flowers/feeders and more time flying around seeking new sources of food.
Sudden Disappearance
If dozens of hummingbirds suddenly vanish from your yard over a 1-2 day period, it almost certainly means a large-scale migration departure has occurred.
Paying attention to these signs can alert you that hummingbird migration is ramping up in your region.
How Long does Hummingbird Migration Take?
The duration of hummingbird spring and fall migration depends on the distance being traveled and number of stopovers made along the way. Here are some general timeframes:
– Shorter migrations of a few hundred miles may take 1-2 weeks
– East/west coast migrants – 4 to 6 weeks typically
– Trans-gulf migrants have longest journey times, up to 2 months
– Southbound migration is often shorter than spring return
– Adverse weather can significantly lengthen migration
– Individual birds may arrive on winter/summer grounds over a 1-2 month period
So while the overall migration period spans 2-3 months from start to finish, individual hummingbirds are only traveling actively for a portion of that time. The rest is spent stopping over or already settled on seasonal ranges.
When does Hummingbird Migration End?
The end date of hummingbird migration in fall is less defined than the beginning, as different species arrive on their wintering grounds at varying times. Here are some general guidelines:
– Most ruby-throated hummingbirds finish migrating by early November
– Rufous hummingbirds largely complete migration by late October
– Anna’s hummingbirds may continue migrating into December
– Some vagrant individuals overwinter in southernmost U.S. states
– Migration wraps up when wintering sites across Mexico/Central America are fully occupied
– This final settlement occurs between November and January
So while the migration period spans August through November, the bulk of hummingbirds have reached their destination by mid-November. The stragglers arrive by early winter, guided by weather and food.
How Many Hummingbirds Migrate Each Year?
It’s challenging to quantify the exact number of hummingbirds migrating, but here are some estimates:
– There are over 300 hummingbird species worldwide
– Roughly 25 species regularly breed in North America
– Tens of millions of individual hummingbirds make the trip
– Ruby-throated hummingbirds number in the many millions
– Rufous hummingbirds also migrate in the multi-millions
– Greater numbers migrate southward in fall vs. northbound in spring
– Number of migrants follows breeding season success – more young = more migrants
While obtaining a precise count is impossible, experts agree that dozens of millions of hummingbirds complete the epic migration each season as they disperse across North and Central America.
What are the Longest Hummingbird Migrations?
For their tiny size, hummingbirds make astonishingly long migration journeys each year. Here are some of the marathon migrants:
Rufous Hummingbird
– Breeds in Pacific Northwest, winters in Mexico
– One way migration route up to 4000 miles
– Many fly southeast through Texas and Gulf Coast
Ruby-throated Hummingbird
– Breeds across Eastern U.S. and Canada
– Winters in Central America from Mexico to Panama
– Makes trans-Gulf crossings of up to 600 miles
Black-chinned Hummingbird
– Western cousin to the Ruby-throat
– Follows similar migration path
– Also crosses Gulf of Mexico in fall and spring
Allen’s & Costa’s Hummingbirds
– Winter in Mexico, summer along Pacific Coast
– Northbound trip follows coastlines and can exceed 2500 miles
These ultra-marathoners complete some of the most incredible migrations in the bird world relative to their tiny sizes.
How many hummingbirds remain in the US for winter instead of migrating?
Most hummingbird species that breed in the U.S. and Canada migrate south for the winter. However, a small percentage of certain species overwinter in the southernmost states instead of making the full migration journey:
| Species | % Overwintering |
| Ruby-throated | ~5% |
| Rufous | 10-15% |
| Calliope | ~20% |
| Anna’s | 35-45% |
| Allen’s | 45-55% |
– Ranges are estimated and can vary considerably between winters
– Generally, western species like Calliope and Anna’s overwinter more frequently than eastern Ruby-throats and Rufous
– Mild winter temperatures allow some hummingbirds to save the effort of completing the full migration
– Providing nectar feeders can help sustain overwintering hummingbirds
The majority still migrate, but those that remain brighten winter for lucky yard owners in the southern U.S. able to host them until spring.
How Do Hummingbirds Know When to Migrate?
Hummingbirds have an innate ability to recognize environmental cues signaling the optimal time to depart on migration. Here’s how they know when it’s time to go:
Internal Biological Clock
Hummingbirds possess an internal circadian rhythm tuned to the seasonally changing day length. As days become shorter in late summer, it triggers their migration instinct.
Fat Stores
Hummingbirds have a physiological drive to pack on as much fat as possible before migration. This excessive weight further stimulates migratory restlessness.
Decrease in Food Supply
The inevitable decline of flower nectar in fall due to frosts and dying blooms provides a direct indicator that migration needs to commence.
Weather Changes
Sudden cold snaps and storms hurry hummingbirds into migration earlier than normal before tough weather arrives.
Urge to Move On
As days shorten, hummingbirds grow more restless and are driven to explore new habitat beyond their breeding territory in preparation for migration.
These innate cues initiate migration on a precise seasonal schedule to maximize timing and survival. Scientists continue working to better understand how hummingbirds integrate these signals.
How Do Hummingbirds Navigate During Migration?
One of the most remarkable aspects of hummingbird migration is their ability to navigate with precision over thousands of miles. Here are some of the ways hummingbirds find their way on migration routes:
Celestial Cues
Hummingbirds use the position of celestial objects like the sun, moon, and stars to determine directions during migration flights.
Landscape Features
Mountains, coastlines, rivers, and other landmarks help hummingbirds orient themselves and identify specific stopover locations along migration routes.
Sense of Smell
Research shows hummingbirds have a strong sense of smell that aids navigation by detecting airborne odor compounds unique to certain habitats.
Magnetic Fields
There is evidence that hummingbirds may be able to detect subtle variations in the Earth’s magnetic fields, providing a built-in compass for migration.
Mental Maps
Hummingbirds appear to possess mental maps of migration routes and key stopover sites passed down through generations and imprinted from birth.
These special skills allow hummingbirds to find their way over thousands of miles with incredible precision as they continue their ancient migration tradition each year.
Conclusion
Hummingbird migration is one of nature’s most remarkable phenomena. As autumn approaches, millions of these tiny birds embark on epic journeys between their summer and winter ranges. Determining exactly when the migration starts is tricky and can vary by species and location. However, there are tells signs like restlessness, sudden disappearances, and increased feeding activity that indicate migration is imminent. While the specific timing is difficult to predict, what remains certain is that another season of spectacular hummingbird migrations lies ahead as these beautiful birds follow their ancient migratory timetables. Their amazing navigational abilities ensure the migration continues, as it has for countless generations. With careful observation of local hummingbird behaviors and patterns, we can gain valuable insight into these birds’ migratory mysteries.
