The red-eyed vireo is one of North America’s most common passerine songbirds. Its penchant for marathon singing sessions has earned it the nickname “preacher bird.”
Oft heard but seldom seen, Vireo olivaceus makes its home in the pine forests of the north or the canopies of broadleaf deciduous trees in the east and south of America.
Its olive-green top colouring, contrasted with its white underside, camouflage it masterfully among the sunbathed leaves in the upper reaches of its arboreal hunting (In Trees) and breeding grounds.
Migratory birds, vireos travel hundreds of miles south each year to winter in the tropics. They return in the Spring, ready to spawn the next generation.
Identity: How to Recognize a Red-Eyed Vireo?
The vireo’s small size and colouration allow it to blend in seamlessly with its treetop surroundings. It can be hard to spot them from down below unless you know just what to look for.
As their Latin name suggests, vireos are characterized by olive-green top feathers. They have a white underside and a blush of yellow along the flanks and under-tail.
Red-Eyed Vireo Identification
| Feathers | Olive-green top, white underside, yellow blush on flanks and undertail. Black crown and eye line, white eyebrow markings |
| Length | 4.7-5.1 in (12-13 cm) |
| Weight | 0.4-.0.9 oz (12-26 g) |
| Wing Span | 9.1-9.8 in (22-25 cm) |
| Profile | Pointed wing feathers, pointed, short tail feathers, angular head, thick neck. |
| Beak | Blue-grey, stout, all-purpose, with slight hook at tip |
| Eyes | Red irises, ranging from a dull red to bright crimson |
| Feet & Legs | Grey-blue, thick |
The red irises responsible for its common name appear dark at a distance but are striking and unmistakable at close range.
Do Males and Females Look Different?
Judging from their prominent features, you’ll be hard pressed to tell male and females of this species apart. They exhibit no sexual dimorphism.
The males tend to weigh more than the females, but that is not always the case. Otherwise, they share the same colorations, patterns, and markings.
What Do Red-Eyed Vireos Look Like in Winter?
Red-eyed vireos maintain the same basic appearance year-round. Like any bird, their feathers lose some shine and vibrancy by the time breeding season ends.
As they molt and grow new feathers, you may perceive a distinct pattern of old and new growth. But, it isn’t enough to make them unrecognizable.
Habitat: Where Do Red-eyed Vireos Live?
The deciduous forests of eastern North America are the primary home of this tree-loving bird, though their range reaches well into the midwestern regions of both the United States and Canada.
Their migration carries them throughout Central America, and even the Caribbean as they make their way to South America for the winter.
It is not uncommon for isolated vagrants to be found along the coastal regions of California, likely attempting to migrate south from their western-most habitats.
Habitat at a Glance:
This wide-ranging species appears for brief periods in several North and South American countries, passing through on their migratory journeys.
| Breeding | United States, Canada |
| Migration | Mexico, Guatemala, Belize, Honduras, El Salvador, Nicaragua, Costa Rica, Panama, Cuba, Jamaica, Dominican Republic. During Winter: Bolivia, Brazil, French Guiana, Suriname, Guyana, Venezuela, Peru, Columbia, Paraguay, and Uruguay |
| Climate | Temperate to Tropical |
| Terrain | Prefers dense, deciduous or mixed forests, particularly those made up of large-leafed shade trees |
Residents in areas that vireos call home are more likely to hear their song than to see them. They stick to the mid to high branches of tall trees, hidden amongst the leafy canopy.
If you’re actively looking for them, you might have to go deep into the woods to find them. They have a preference for trees bordering interior clearings and waterways.
Where Are They During the Day & Night?
Red-eyed vireos are most active during twilight, a prime time to catch their favoured prey: insects.
Day or night, they remain in the same treetop environment, coming down only infrequently in search of food or nesting material.
Where Do I Find Red-Eyed Vireo’s?
Wherever broadleaf trees stand dense enough to provide sufficient concealment, vireos are happy to hunt and breed.
This includes wooded suburbs, urban parkland, and cemeteries. They also frequent orchards, and occupy plantations in the tropics.
Breeding: Red-eyed Vireo Mating and Nesting Habits
In many respects, red-eyed vireo relationships resemble the ideal among humans. They form monogamous pairs, claim a territory that they fiercely defend, and raise their young as a team.
Of course, human parents can only look on enviously at the swift maturation of the red eye’s chicks. In just a little over one month, they’re all grown up and ready to fend for themselves.
When Do Red-Eyed Vireo’s Breed?
As is typical of many species, mating season begins in the spring for the red-eyed vireo, around mid-April. It lasts through the summer and ends in August.
What Are Their Courtship Rituals?
The vireo male starts the season off by establishing his own territory. Once done, he sings his little heart out in an attempt to attract “the one.”
Once a likely female appears, two approaches have been observed. One, the more genteel method, involves a swaying dance.
The male displays himself to the female, with his feathers, slicked down and sways his body left and right. If things go well, the pair will rapidly flutter their wings.
Conversely, some males chase and pin the females they find desirable. It’s a tactic that lacks finesse, but, sometimes, it works.
How do They Build Their Nests?
Once the birds have consummated their relationship, it’s time to build the nest. This is a job that the female takes on, while the male defends their territory.
Red-eyed vireo nests are distinctive both for their construction and their placement. The female scouts locations until she finds a sapling that meets her needs.
The typical choice is a slender limb with a forked end, well concealed by the canopy, . Over a period of about 5 days, she carefully builds a bowl shaped structure that hangs from the fork.
The outer portion of the nest is built from small sticks, roots, stems, and tree bark. The interior lining consists of pine needles, grass, and soft animal hair.
What do Red Vireo Eggs Look Like?
The female lays 3-5 eggs in a season. They are white, ovoid, and have brown or black spots, primarily clustered at the wider end.
What Do Red Vireo chicks Look Like?
After an incubation period of 14 days, the eggs hatch to reveal completely helpless little chicks.
It takes 2 weeks of constant care and protection from mom and dad before the chicks become fully feathered fledglings. These new feathers are almost uniformly gray-green.
The chicks are born with brown eyes. The red colouration doesn’t develop until the end of their first year. Other than their colouration, however, vireo chicks look just like adults.
Diet: What do Red-eyed Vireos Eat?
Many birds alter their diets seasonally, but red-eyed vireos exemplify this practice. Technically insectivores, you would never know it by observing them in their tropical wintering grounds.
These foragers are masters of the hover-gleaning technique. By hovering in place, they can pick their unsuspecting meals from locations otherwise inaccessible.
What Do They Eat in the Spring & Summer?
In the breeding season, a vireo’s diet consists primarily of insects, with the occasional arthropod or mollusc.
This is due to a greater protein requirement, to ensure the health and proper development of their chicks.
During this time, their menu includes:
- Caterpillars
- Beetles
- Moths
- Flies
- Cicadas
- Wasps
- Dragonflies
- Ants
- Spiders
- Snails
What Do They Eat in the Fall & Winter?
Near the onset of fall, vireo fledglings are able to fend for themselves. The focus switches from chick-rearing to the bulking up for the coming migration.
From this point, on through winter, insects can rest easier, because the vireos gain a taste for berries and fruit. The following rank among their favourites:
- Elderberries
- Dewberries
- Blackberries
- Blueberries
- Bayberries
- Sumac
- Virginia Creeper
- Sassafras
- Spicebush
- Arrowwood
Migration: Where Do Red-eyed Vireos Go In When Migrating?
Birders looking for vireos within the United States will find them in abundance in the east and midwest during the warm months. To the south and west of Nebraska, their numbers dwindle.
Regardless of the time of year, you won’t find vireos at all once you reach Nevada and Colorado. For vireos, the deserts and mountains are just too inhospitable.
When Do They Migrate?
The migration south begins in August. Over a 4 month span, the entirety of the estimated 130 million red-eyed vireos flees the cruel cold of Winter, reaching their tropical destination by December.
When the season passes, they make the journey in reverse, setting out in March, and returning to their now refreshed breeding grounds by June.
They travel almost exclusively at night, in both directions. The cover of darkness allows them to safely travel long distances in the open.
Where Do Red-Eyed Vireos Go in Spring & Summer?
During the breeding season, these birds return to the temperate, deciduous groves that they favor throughout Eastern and Central North America.
Where Do They Go in Fall/Winter?
Their wintering grounds are in South America, focused on within the Amazon basin. Here, they trade their oaks, maples, and birches for palm trees.
The farthest south they go is Uruguay, and the Andes mark the border of their territory to the west.
What Hazards Do They Face During Migration?
Red-eyed vireos travel over 600 miles on their semi-annual migrations. The rigours of these harrowing journeys claim many birds along the way.
Sheer exhaustion is a major danger, particularly for the birds that fly directly over the Gulf of Mexico. If their energy gives out, they plummet into the waves.
Inclement weather is another threat. Vireos respond to overcast conditions by flying further inland, where there is shelter. Those that don’t, suffer for it.
Predators are also a concern, though their size, speed, and camouflage make them a difficult meal. Still, sharp-shinned hawks are a particular threat to vireos.
How Do Red-eyed Vireos Live and Interact With Others?
Change is a theme for this little green bird. They not only alter their diets throughout the year, they change their way of life.
This ability to adapt to circumstance serves them well, as their populations have barely declined, despite urban spaces gradually consuming their favoured territories.
But, if you’re trying to characterise their behaviour, their changeable nature can frustrate your efforts. Depending on where and when you see them, they may seem like two entirely different birds.
Are Red-Eyed Vireos Aggressive?
Yes…and no.
During the breeding season, vireos are always ready for a fight. Females staunchly defend the nests, while the male patrol tirelessly for intruders.
When they encounter enemies, vireos engage in a threatening display. They stand taller, with crest feathers raised to add height and fan their tail feathers while calling their displeasure.
If this isn’t enough to scare off their foes, they will unleash a vicious pecking attack, and harry the enemy until they’ve been chased out of the territory, or worse.
But, they take a break from this behaviour when the time to migrate comes around, at least when it comes to others of their species.
Are They Territorial?
Yes, but again the answer varies with the season. The first order of business for males returning from the south is to find and secure their territory.
Once joined by a female, they defend their space together. In fact, their aggression is mainly exhibited in this defence of their home and children.
In their wintering grounds, they are far more relaxed. Among the palms and mangroves, they share space with fellow vireos, as well as other bird species.
Are They Solitary Or Social?
Their aggression and territoriality in the Spring and Summer months make it unsurprising that they are mostly solitary during that time.
The only exceptions are their mate, and, if they are lucky, their chicks. Vireos are not interested in making friends.
This lasts until, you guessed it, migration begins. These mercurial green birds then band together in flocks up to 30 members strong. Past peckings are put aside, no hard feelings.
Are Red Vireos Noisy Birds?
Perhaps the largest portion of the red-eyed vireo’s fame, and infamy, is owed to its iconic singing.
If you live in their territory, you’ve almost certainly heard it. The male trills a few broken notes, finishing high like a question, followed by the same, but ending low, like an answer.
This curious sing-song self-interrogation can last, quite literally, all day long. One vireo virtuoso reportedly sang over 20,000 of these songs in one day.
But, they don’t just sing. Both the male and female use a variety of calls to communicate, the most common being a myaah sound, often deployed as part of an aggressive display.
Females tchet at their mates for food, and the males tsherrrr in the heat of battle. Vireos are quite “talkative” birds.
Can You Tame Red Vireos?
Based on their preferred habitat and traits, you can probably already see how difficult it would be to keep a red-eyed vireo in captivity.
They spend very little time down on the level of humanity, and their high-flying arboreal lifestyle would be difficult to emulate. Taming them seems out of the question.