Willow Flycatcher

Quick Take

• Most birds learn their songs from their parents, but the willow flycatcher breaks that rule in a way scientists find remarkable. See the innate song fact →
• One species looks so identical to the willow flycatcher that even experts can't tell them apart. The only exception is one narrow trick. Compare the look-alike species →
• A bird that quietly invades willow flycatcher nests may pose a bigger threat than any predator in the sky. Discover the cowbird threat →
• Its average lifespan sounds bleak, but that impression changes when you see how long some individuals actually survive. Check the lifespan details →

The willow flycatcher (Empidonax traillii) is a small, slender, insect-eating passerine. It is native to North and South America, where they inhabit wet meadows filled with willows and other shrubs near water. They spend their days perched in bushes, sallying out to catch insects mid-air or hovering over leaves. This bird sings a tune that is unique to its species and even varies among subspecies.

Willow Flycatcher Amazing Facts

• Unlike most birds that learn their songs from their parents, willow flycatchers hatch already knowing their unique tune.
• The alder flycatcher and willow flycatcher are almost impossible to tell apart. You can only identify them by their song and range.
• Willow flycatchers arrive at the breeding grounds later in spring than most flycatcher species.
• They can travel up to 5,000 miles between their wintering and breeding grounds.

Where To Find the Willow Flycatcher

Willow flycatchers live in willows or other shrubs near water, but their exact habitat varies by subspecies. Those in the Northwest may utilize drier scrubby areas, while in the Southwest, you can find them in river islands and scrubby fields. They are more lenient with their wintering grounds and can inhabit pastures, woodland edges, and clearings. They are most abundant on their breeding grounds from late May to June, where they are likely to be perched on willows singing their unique tune. 

Nests

Females pick a nesting spot in a deciduous shrub or tree, typically a willow, and place it two to five feet above the ground in a fork of a branch. The female weaves an open cup using grass, bark strips, and plant fiber, and lines the insides with horsehair, grass, plant down, and other soft material. The nest is three inches across and three inches tall, taking around five to ten days to complete in the first breeding season. This species returns to the same nesting site each year and incorporates nesting material from the previous year to build a new nest.

Classification and Scientific Name

Willow flycatchers (Empidonax traillii) belong to the Tyrannidae family, which encompasses the tyrant flycatchers, covering 400 species of New World passerines. The Empidonax genus is a group of small, insect-eating flycatchers. The name in Ancient Greek means “gnat master.” 

There are four recognized subspecies of willow flycatcher separated by location:

• E. t. brewsteri — Pacific Slope
• E.t. adastus — Great Basin/Northern Rockies
• E. t. extimus — Southwest
• E. t. Traillii — East Coast to the Western Rockies

Size, Appearance, and Behavior

The willow flycatcher is small and slender, weighing 0.4 to 0.6 ounces and measuring 5.1 to 6.7 inches long, with a 7.5 to 9.4-inch wingspan. despite their relatively small size, they are one of the largest in their genus. they have fairly long wings, a long thin tail, and straight, broad bills for catching insects. Males and females appear very similar. They are brownish olive above and white below with a slight yellow wash, with darker wings showing white and buff streaks. This species also has a very thin white eye ring.

These birds live in the understory and are named for their propensity for flitting between willows and shrubs. They perch on the edge of willows and fly out to catch their prey. 

The flycatcher’s song is the easiest way to identify the species. Male willow flycatchers typically do most of the singing. Although females can also sing, they are usually quieter. Their songs are hoarse and last around one second. It may sound like someone zipping up a coat or a wheezy “fitz-bew.”

Migration, Pattern, and Timing

Willow flycatchers are long-distance migrants. They breed in Southern Canada and throughout most of the United States, except the Southeast. They migrate through Northern Mexico before reaching their wintering grounds in Southern Mexico, Central America, and Northern South America.

Diet

Willow flycatchers are mainly insectivorous and use perches to catch their prey.

What Does the Willow Flycatcher Eat?

Their diet consists primarily of insects, including bees, wasps, winged ants, damselflies, beetles, caterpillars, moths, butterflies, true bugs, and many more. They also eat spiders, seeds, and berries on occasion. Their berry diet includes raspberries, blackberries, currants, and dogwood berries. This species hunts by perching in low trees and tall shrubs, sallying out to catch insects mid-air. They may also hover over leaves and other foliage to carefully pluck their prey.

Predators, Threats, and Conservation Status

The IUCN lists the willow flycatcher as LC or “least concern.” Due to its wide range and extremely large population, this species does not meet the qualifications for “threatened” status. These birds are common within their range, but they have undergone a moderate decline since 1970. This species faces threats from habitat loss, habitat degradation, overgrazing, and parasitism from the brown-headed cowbird. 

What Eats the Willow Flycatcher?

Willow flycatchers have several natural predators, including snakes, voles, ravens, hawks, owls, and weasels. King snakes and milk snakes are known for stealing flycatcher eggs, and other species, like great horned owls, long-tailed weasels, and Cooper’s hawks, will eat their nestlings. These flycatchers may give chase to intruders, including the brown-headed cowbird, which lays its eggs in flycatcher nests.

Reproduction, Young, and Molting

The courtship behavior of the willow flycatcher is not well-known. However, it likely involves males chasing females and singing. These birds are primarily monogamous, often pairing with the same mate each breeding season. Females lay three to five buff to white eggs with brown spots and incubate them alone for 12 to 15 days. Once hatched, both parents bring food and feed the nestlings. Nestlings are born with eyes closed and are naked except for patches of down on their heads and backs. The young take their first flight when between 12 and 14 days old. They undergo their first pre-basic molt before leaving the breeding grounds. The willow flycatcher has an average lifespan of about 1 to 1.6 years in the wild, though individuals have been recorded living up to 11 years.

Population

The global willow flycatcher population is estimated at 8.1 million mature individuals. While their population is not severely fragmented, numbers are continuing to decline. This species has been moderately declining at an average rate of 12% over ten years. Due to its vast population, the decline is not rapid enough to warrant a vulnerable status.