Hummingbirds are beloved for their beauty, size, and fascinating flight. Their arrival each spring is eagerly awaited by people across North America who enjoy seeing these tiny birds visit their gardens. However, many people have noticed fewer hummingbirds coming to their feeders and flowers this year. What’s behind the apparent decline in hummingbird numbers?
The migration is delayed
There are several factors that may be contributing to the lower number of hummingbirds this spring. The most likely explanation is that the migration of these birds from their wintering grounds in Mexico and Central America is simply delayed.
Ruby-throated hummingbirds depart their winter range and head north to breeding areas in the United States and Canada between February and May each year. The exact timing of the migration is dependent on a number of factors including weather, food availability along the migration route, and competition for breeding territories.
This year, unusual weather patterns like late spring storms may have disrupted the migration. Cool temperatures and rain make it harder for the tiny birds with fast metabolisms to find enough nectar to fuel their journey. Ruby-throats start migrating well before the flowering plants they rely on have started blooming farther north. Late blooming of these essential food sources due to the cold spring would delay the migration.
What is the ruby-throated hummingbird’s migration route?
Ruby-throated hummingbirds follow established migration routes each spring and fall. In spring, the majority of hummingbirds cross the Gulf of Mexico from Mexico’s Yucatan Peninsula to the Gulf Coast of the United States before dispersing farther inland. Unfavorable weather over the Gulf like storms, high winds, or cool temperatures can force the tiny birds to stop short of the coast and delay the crossing.
How is food availability affecting the migration?
Ruby-throated hummingbirds rely on nectar from flowers and blooming trees as their main food source while migrating. If the bloom of spring flowers and blooming trees is delayed due to cold weather, it limits food availability for the migrating birds and causes them to pause their journey until blossoms open farther north.
A shortage of food along the migration route will slow the pace of migration. Hummingbirds need to rest and refuel regularly as they travel north to replenish the calories burned by flying and to rest before continuing. When food is scarce, the pace of migration is reduced.
More hummingbirds may arrive later
Though fewer hummingbirds may be appearing at the usual time, it’s likely more birds will show up in the coming weeks as the delayed migration progresses. The populations of ruby-throated hummingbirds are stable so there should be no long-term drop in their numbers.
Birders in northern states may just need to wait a bit longer for hummingbird activity to pick up as the bulk of the migration reaches their area over the next few weeks. Monitoring hummingbird sightings through citizen science programs like the Journey North Ruby-throated Hummingbird migration map can provide clues to when higher numbers will arrive.
How cold weather delays nesting
In addition to delaying migration, an unusually cold spring can also delay nesting attempts. Males typically arrive at the breeding grounds a week or two before females to establish territories. But if freezing temperatures and storms linger, the nesting timeline gets pushed back.
Hummingbirds won’t start building their tiny nests until more consistently mild weather allows for access to nesting materials like soft plant down and spiders’ silk webs for binding the nests together. Without suitable conditions and materials, nesting will be delayed until later in the season.
When do hummingbirds normally nest?
Ruby-throated hummingbirds nest between April and June depending on the latitude. Southern populations may nest as early as March while northern hummingbirds nest in May through July. The tiny nests only take 5-10 days to construct but cold temperatures and precipitation can halt progress and extend the timeline substantially.
What can we do to help hummingbirds?
While little can be done to hasten the arrival of more hummingbirds this spring, a few measures can help support their migration and nesting.
- Fill hummingbird feeders with fresh nectar so food is available when the birds arrive.
- Add more feeders to provide more feeding ports for hungry migrants.
- Provide an assortment of nectar-rich flowers in the garden like columbines, bee balm, and trumpet vines.
- Avoid using pesticides which reduce insect populations the birds rely on for protein.
- Supply clean nesting materials like pet and human hair, feathers, or cotton balls.
- Keep cats indoors to protect birds.
With a little support, the hummingbirds will return in normal numbers it just may take a little longer this year. The joy of seeing the first flash of iridescent red or green darting through your garden will be just as thrilling even if it is slightly delayed from prior years.
How weather patterns affect migration
Not only can localized weather events like storms delay migration, but larger climate patterns over a season also influence the timing and pace of hummingbird migration each year. Understanding these patterns provides helpful context on the migration timetable.
ENSO
ENSO stands for El Niño Southern Oscillation, a fluctuation between warmer and cooler ocean temperatures in the Equatorial Pacific that shifts global weather patterns. During the El Niño phase, warmer ocean temperatures and rising air support a more active Pacific jet stream which tends to funnel storm systems across the southern U.S.
The increased storminess disrupts hummingbird migration across this key route. Data shows El Niño years result in the latest first sightings of hummingbirds in spring migration compared to neutral or La Niña cycles.
PDO
Shifting sea surface temperatures in the Northern Pacific also influence weather trends over North America in phases known as the Pacific Decadal Oscillation or PDO. The cool phase tends to promote cooler, wetter weather across the region which can delay plant blooming and hummingbird migration.
Studies find spring migration arrives nearly 10 days later when the PDO is in its cool phase compared to the warm phase. Records show the PDO has trended in its negative or cool phase over the past few years which may be contributing to slower spring migrations.
How can climatic cycles be predicted?
Forecasters can predict transitions between ENSO and PDO phases months in advance using ocean monitoring networks, atmospheric models, and climate science. This data can provide early indications of weather pattern shifts that may favor delayed spring migrations well before the birds begin their journey north.
Recent US weather patterns
In addition to larger oscillations, specific recent weather events across the United States likely contributed to the late start of this year’s hummingbird migration.
Late Cold Snap
A late season Arctic cold front brought unseasonably cold temperatures to much of the country in early April. Freeze warnings stretched as far south as Texas and Florida. This delayed flowering and forced hummingbirds to pause migration due to frigid temperatures and lack of food.
| Location | Minimum temperature | Departure from average |
|---|---|---|
| Dallas, TX | 32°F | -19°F |
| Houston, TX | 38°F | -16°F |
| New Orleans, LA | 42°F | -17°F |
The chilly weather kept hummingbirds from advancing up the Gulf Coast and delayed bloom of food sources farther north by weeks.
Late Season Gulf Coast Storms
In addition to chill, a series of strong storm systems pummeled the Gulf Coast region in late April and May dumping heavy rain and causing flooding from Louisiana to Florida. These types of weather patterns are common during La Niña winters and can linger into spring.
| Location | Precipitation total | Departure from average |
|---|---|---|
| New Orleans, LA | 12.7 inches | +9.2 inches |
| Mobile, AL | 13.4 inches | +10.31 inches |
| Tallahassee, FL | 8.2 inches | +4.72 inches |
Rain, wind, and storms make Gulf crossing more difficult for small migrating birds like hummingbirds. Lingering storm systems likely caused delays in crossing from Mexico and Central America to the Gulf Coast pushing back arrival farther north.
Status of hummingbird populations
While fewer hummingbirds may be gracing backyards and feeders so far this year, populations of North American species remain stable overall. No major declines have been reported that would indicate a drop in total numbers of birds according to data from monitoring programs.
Partners in Flight estimates
The tri-national Partners in Flight network monitors landbird populations across North America including hummingbirds. Their recent report
estimates the total ruby-throated hummingbird population at 7 million with a breeding population of 5 million across their summer range.
Breeding bird survey trend data from 1966-2019 shows no significant population decline and a 0.05% annual increase.
Status in Mexico and Central America
The overwintering population of ruby-throated hummingbirds in Mexico is estimated at 1-2 million birds mostly concentrated along the Gulf coast and Yucatan Peninsula.
Monitoring indicates stable winter populations in Mexican reserves and across their Central American winter grounds. Illegal trade in wild-caught hummingbirds remains a threat, but has not impacted overall numbers.
How to track hummingbird migration
Wondering when the bulk of hummingbirds will reach your area? Here are some tools to monitor the migration’s progress this year:
Journey North community science maps
Anyone can report first spring hummingbird sightings to the Journey North project. Their real-time hummingbird migration map shows the leading edge of arrivals across the country with sightings from as far north as Canada reported by thousands of participants.
eBird historical arrival tool
The eBird database compiles millions of bird sightings submitted by users across the hemisphere. Their hummingbird arrival map allows you to see median spring arrival dates over past years for your location and compare to the current season.
Local nature centers and parks
Connect with nearby nature education centers, parks, refuges, and sanctuaries to ask about their hummingbird monitoring data. Onsite naturalists track the birds’ arrival and can provide location-specific updates.
Though the start of spring hummingbird migration is running late this year, ample time remains for their populations to traverse the route north and return to summer breeding areas. Providing a few simple resources in our backyards to help the birds along their way allows us to overcome temporary environmental delays and enjoy the company of these colorful migrants.
Conclusion
The lower number of hummingbirds in many areas this spring is most likely due to a delayed migration caused by unusual weather patterns. Cold temperatures and late storms disrupted the normal nectar resources and conditions required by the tiny birds as they travel north from Mexico and Central America. However, monitoring indicates stable overall hummingbird populations, so more birds should arrive over the coming weeks as migration progresses. Tracking tools, weather data, and climate patterns can provide insights on when the bulk of the migration may reach each latitude. In the meantime, we can support hummingbirds’ journeys by providing nectar feeders and flowers in our gardens so their flashy buzzing flights will return to enchant us as they do each spring.
