The Varied Thrush is a medium-sized songbird native to the Pacific Northwest region of North America. Characterized by its bold black and orange plumage, the Varied Thrush is notable for its rich, flute-like song and elusive nature. Though not endangered, Varied Thrush populations have declined in recent decades due to habitat loss and climate change.
Physical Description
The Varied Thrush is approximately 8-10 inches in length with a wingspan of 12-15 inches. It weighs between 1.5-2.4 ounces. The male Varied Thrush has striking black plumage on its back, wings, tail, and head with bright orange markings on its throat, breast, sides, and eyebrows. The female is similar but has more brownish-gray plumage overall with duller orange markings. Both sexes have a black band across the chest.
Their slender bill is black and slightly curved, adapted for picking insects off trees and probing soil. Their legs and feet are yellow-orange. Varied Thrush fledglings resemble the female, with brownish-gray plumage dotted with buffy scaling until they molt into adult plumage around August.
Habitat and Range
The Varied Thrush inhabits coniferous and mixed forests across a large swath of western North America. Their breeding habitat extends from southeast Alaska through western Canada south to northern California. They winter along the Pacific coast from southern Alaska to central California.
Within these forest habitats, Varied Thrushes prefer areas with dense understory vegetation and tall trees for nesting and roosting. They are often found near openings in the forest canopy like clearings or edges. Their elevational range spans from sea level up to 10,000 feet.
Some key habitat features favored by Varied Thrushes include:
– Mature conifer forests with fir, hemlock, spruce, pine, and cedar trees
– Areas with berry-producing shrubs like salal, huckleberry, and elderberry
– Presence of snags and fallen logs for nesting and foraging
– Streams, bogs, and wetlands that attract insect prey
Migration Patterns
The Varied Thrush is a migratory bird, making relatively long migrations between its breeding and wintering grounds each year. Here are some key details about their migration:
– They begin migrating south from September to November. Early winter snow and food scarcity triggers migration.
– Spring migration north occurs from March to May as they return to nesting territories.
– They often migrate at night and travel in loose flocks during migration.
– Their migrations are thought to generally follow the Pacific Flyway route, a migratory path along the western coast.
– Most winter from southern Alaska down through Oregon, rarely as far south as Baja California.
– Some Varied Thrushes, especially juveniles, undergo “irruptive” migration in some years when food is scarce – straying east into unusual areas.
– Their migrations can span 1500 miles or more between breeding and wintering grounds.
Diet
The Varied Thrush has a diverse diet consisting of insects, berries, and other fruits. Their feeding habits change based on seasonal availability:
– Insects: Beetles, ants, caterpillars, wasps, and spiders are eaten during spring and summer, especially while breeding. They forage by probing soil and litter, gleaning trees, and flycatching.
– Berries: In fall and winter they switch to eating fruit and berries including salal, huckleberries, blackberries, elderberries, wild cherries, grapes, figs, and more.
– Other fruits: Apples, pears, and other cultivated fruit from orchards may also be eaten when available.
– Seeds: They supplement their diet with small seeds from trees and shrubs.
– Sap: They occasionally drink sap from wells excavated by sapsuckers.
The Varied Thrush employs several foraging techniques to find food, including scanning from a perch, ground-foraging by hopping and scratching leaf litter, probing bark crevices, and picking through decaying logs.
Season | Diet |
---|---|
Spring | Insects, especially beetles |
Summer | Insects, berries |
Fall | Berries, fruit |
Winter | Berries, fruit, seeds |
Breeding and Nesting
Varied Thrushes breed in late spring and summer across the forests of the Pacific Northwest. Here are some key facts about their breeding biology:
– Breeding occurs from April to August, with peak activity in June.
– They are monogamous, pairing up with a single mate for the breeding season.
– The male sings beautiful flute-like songs from high perches to attract a female and defend his territory.
– The nest is an open cup built by the female, made from grasses, moss, bark strips, and conifer needles. It is well hidden on a horizontal branch or in a shrub 1-25 feet above ground.
– A typical clutch contains 3-4 pale blue eggs which are incubated by the female for 12-14 days.
– The altricial hatchlings are tended by both parents for 10-15 days until fledging from the nest. The parents continue feeding them for several weeks after leaving the nest.
– Varied Thrushes frequently renest if their first attempt fails due to predation or weather. They may raise two broods in a season.
– Nest predators include Steller’s Jays, squirrels, and snakes. Adults may be preyed on by sharp-shinned hawks.
Nesting Facts
Nesting Fact | Description |
---|---|
Nest Placement | Hidden in conifer tree or shrub 1-25 ft up |
Nest Materials | Grasses, moss, bark, needles |
Clutch Size | 3-4 eggs |
Incubation Period | 12-14 days |
Nestling Period | 10-15 days |
Broods per Season | 1-2 broods |
Conservation Status
While still a fairly common bird over much of its range, Varied Thrush populations have declined by an estimated 45% between 1966 and 2015, according to the North American Breeding Bird Survey. This has led to increasing conservation concern for the species.
Here are some key threats facing the Varied Thrush:
– Habitat loss due to logging, urbanization, and forest fires
– Spread of non-native plants crowding out native vegetation
– Climate change altering forest composition and insect populations
– Predation from increasing numbers of corvids like jays and crows
– Collisions with windows and other structures during migration
– Vehicle collisions, especially during irruptive migration years
Efforts to protect remaining intact mature and old growth forests across their range is key to conservation of the Varied Thrush. Planting native berry-producing shrubs and vegetation on public lands and in backyards can also support populations. Reducing collisions through bird-friendly architecture is another way to help Varied Thrush numbers rebound.
Fun Facts
Here are some interesting tidbits about the charismatic Varied Thrush:
– Their scientific name, Ixoreus naevius, means “mottled with branched marks”, referring to the spotted pattern on their breast.
– Varied Thrush have specialized feathers on their rump called “powder down” that continuously grow and break down into a fine powder. They spread this on their plumage while preening to maintain water resistance.
– The male’s song starts with a few sharp whistles then cascades into a melodious warbling sound. Females may also sing, especially in winter flocks.
– Both parents develop a bare brood patch on their belly to transfer heat more efficiently to eggs during incubation.
– Young Varied Thrushes learn their species’ song by listening to adults, eventually mastering the vocalization after repeated attempts.
– They rub crushed millipedes on their feathers, possibly to deter parasites. The millipedes release defensive chemicals including cyanide!
Where to See Varied Thrushes
Your best chances of spying a Varied Thrush are by exploring forests in the Pacific Northwest, especially along the coast. Here are some top sites:
– Olympic National Park, Washington – Hike through mature rainforests around Lake Crescent and Sol Duc.
– Mount Rainier National Park, Washington – Look in dense understory vegetation at Ohanapecosh and Paradise.
– Crater Lake National Park, Oregon – Take winter snowshoe walks to spot them feeding on mountain ash berries.
– Redwood National and State Parks, California – Search for thrushes probing the forest floor on trails like Lady Bird Johnson Grove.
– Mount Hood National Forest, Oregon – Visit ruined orchards and timber clearings where they forage for fruits.
Any large park or nature reserve with older coniferous or mixed forests, berry thickets, and wetlands could host Varied Thrushes. Make sure to watch and listen closely for these secretive songbirds!
Conclusion
With its handsome plumage and melodious song, the Varied Thrush is a treasured bird of North American forests. Though populations have declined from historical numbers, this elusive thrush can still be found across its Pacific coastal range with some targeted searching. Preserving mature, dense forests and providing artificial food sources like native fruit trees and shrubs will give Varied Thrush the habitat they need. Appreciating the sight and sound of Varied Thrushes where they occur will help motivate ongoing conservation for this special species.