Hummingbirds are often thought of as summer visitors, flitting around gardens and feeders during the warmer months. Most people assume they disappear as soon as summer ends, headed south for the winter.
But lately, something interesting has been happening: bird enthusiasts are reporting seeing hummingbirds much later into the fall, and even into the winter months.
So, when do hummingbirds leave? And why are some sticking around longer than expected? This article explores the factors that influence hummingbird migration and examines the intriguing phenomenon of “vagrant” hummingbirds.
The Traditional Hummingbird Migration Pattern
Hummingbird migration is a fascinating phenomenon, driven by the changing seasons and the availability of food sources.
The Eastern Exodus
In the eastern United States, the ruby-throated hummingbird is the most common species. These tiny dynamos typically begin their journey south by early October. They’re triggered to leave by decreasing daylight and a decline in the nectar sources they depend on. Hummingbirds are very sensitive to changes in the photoperiod, or the amount of daylight in a given day.
Western Migration Routes
Out west, the rufous hummingbird undertakes an impressive long-distance migration all the way from Alaska to Mexico. However, not all western species follow the same pattern. Anna’s hummingbird, for example, has a different migration style.
It’s important to remember that not all hummingbirds migrate to the same location or at the same time. Some species even have year-round resident populations in certain areas.
Vagrant Hummingbirds: When “Leaving” Isn’t So Clear-Cut
The question of when hummingbirds leave gets a little more complicated when you consider what ornithologists call “vagrant” hummingbirds.
What’s a vagrant hummingbird?
A vagrant hummingbird is simply one that’s found outside of its usual territory. For example, species of western hummingbirds like the Rufous and Black-chinned Hummingbird are more and more often seen in the eastern part of the country during the fall and winter months.
Why does vagrancy happen?
Several factors may contribute to vagrancy:
- Genetics: Some birds may simply be genetically predisposed to migrate in a different direction than others. Maybe their navigational skills are a little off, and they just get lost.
- Environmental changes: Climate change could be altering traditional migration patterns, or habitat loss may be forcing hummingbirds to look for new places to live and feed.
Pennsylvania: A case study
Since 2003, birders in Lycoming County, Pennsylvania, have spotted and documented multiple western hummingbird species. At least eight sightings have been confirmed as Rufous Hummingbirds, and there have been a half-dozen or so more sightings of Rufous/Allen’s Hummingbirds that couldn’t be definitively identified.
In fact, it’s not unusual for Pennsylvania birders to spot about 10 western hummingbird species each year.
How late-staying hummingbirds survive
Even though most hummingbirds head south when the weather turns colder, some stick around a bit longer. That begs the question: How do they survive?
Torpor: A key adaptation
Western hummingbirds are particularly well-adapted to colder temperatures. One of their tricks is to enter a state of torpor, which is a temporary period of decreased physiological activity. Torpor allows them to conserve energy when the weather is cold or when food is scarce.
During torpor, a hummingbird can significantly lower its body temperature, which also lowers its metabolic rate. This allows the bird to survive nights when the temperature drops.
Diet beyond nectar
Most people associate hummingbirds with nectar, but hummingbirds are not exclusively nectarivores. They also eat insects, which provide them with essential protein.
Even in the colder months, some insects remain active, and hummingbirds will eat small insects and spiders to supplement their nectar diet. Insects are an essential food source for hummingbirds both during migration and in the winter.
Supporting Late-Staying Hummingbirds: What You Can Do
If you still have hummingbirds hanging around as the weather turns colder, there are things you can do to help them along.
Keep Those Feeders Out
One of the best things you can do is leave your hummingbird feeder up well into the fall and winter. A clean feeder can attract hummingbirds who have wandered off course and are looking for a reliable source of food. This is especially important when the flowers they usually feed on are no longer in bloom.
Feeder Maintenance
When freezing weather is predicted, it’s important to take steps to keep the feeder from freezing solid. If the temperature is expected to dip below 25°F, it’s probably best to bring the feeder indoors overnight. Otherwise, you can try using a heating device designed for hummingbird feeders or an insulated cover. Be sure to check the feeder regularly and thaw it out if it freezes.
Sugar Solution Recipe
The best recipe for hummingbird food is simple: a 4:1 mix of water and granulated sugar. Just be sure to avoid honey, artificial sweeteners, or red food coloring, all of which can be harmful to hummingbirds.
Spotting unusual hummingbird visitors
It can be tricky to identify hummingbirds that don’t normally live in your area, especially the females and young ones. But if you spot a hummingbird after mid-October, pay close attention!
One clue that a hummingbird is from the west is orange coloring in its tail feathers. Field guides and online resources can also help you identify different species.
Be sure to report any unusual sightings to local birding groups. Data from citizen scientists like you helps researchers track bird populations.
Wrapping Up
It’s important to understand when hummingbirds typically migrate through or away from your area. But keep in mind that more and more people are spotting “vagrant” hummingbirds, birds that are outside of their usual range.
You can help researchers track changes in hummingbird populations by reporting your sightings. Citizen scientists play a vital role in monitoring range expansions and shifts, especially as the climate changes.
Whether you live in an area where hummingbirds are year-round residents or just visitors, leaving your feeders out (and keeping them clean!) can make a big difference to these tiny, beautiful birds.