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    Varied Thrush Life History

    Habitat

    Habitat ForestsThe Varied Thrush lives in dark, wet, mature forests in the Pacific Northwest. In its breeding range, which covers Alaska and tapers as it extends south to northern California, it inhabits forests dominated by coastal redwood, Sitka spruce, red alder forests, western hemlock, western red cedar, western larch, or Douglas-fir. In winter it may be found in a broader range of habitats, including parks, gardens, lakeshores, and riparian areas where fruit and berries are abundant. Back to top

    Food

    Food InsectsDuring breeding season, Varied Thrushes eat insects and other arthropods from the leaf litter; in winter they eat mostly berries and nuts. They forage by seizing dead leaves in their bill and hopping backward to clear a spot of ground before examining it for prey. In fall and winter, they switch to fruits and acorns, forming loose flocks around their food. Some of their typical fruits are snowberry, apple, honeysuckle, madrone, mistletoe, manzanita, toyon, ash, salal, cascara, dogwood, blueberry, huckleberry, salmonberry, and thimbleberry.Back to top

    Nesting

    Nest Placement

    Nest TreeFemales probably choose where to build the nest—usually in the understory of a mature forest, often in a spot surrounded by old nests (or even directly on top of one). They are usually around 10 feet off the ground and poorly concealed, close to the trunk of a small conifer.

    Nest Description

    The female gathers nest material and weaves an outer layer of fir, hemlock, spruce, or alder twigs. She adds a middle layer with rotten wood, moss, mud, or decomposing grass, which hardens into a dense cup about 4 inches across and 2 inches deep. Finally, she lines the cup with fine grasses, soft dead leaves, and fine moss, and drapes pieces of green moss over the rim and outside of the nest.

    Nesting Facts
    Clutch Size:1-6 eggs
    Number of Broods:1-2 broods
    Egg Length:1.1-1.4 in (2.8-3.5 cm)
    Egg Width:0.8-0.9 in (1.9-2.3 cm)
    Incubation Period:12 days
    Nestling Period:13-15 days
    Egg Description:Light sky blue, sometimes with dark-brown speckles.
    Condition at Hatching:Eyes closed and bodies mostly bare with sparse patches of gray down.
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    Behavior

    Behavior Ground ForagerVaried Thrushes forage on the ground, periodically moving to higher perches in the understory to sing or move between foraging sites. Males reach the breeding grounds before females and start singing to establish territories. They have several threat displays, beginning by cocking the tail, turning it toward an intruder, and lowering the wings. If the adversary remains, the displaying bird will face off, lowering its head, raising and fanning the tail, and spreading its wings out to its side. Occasionally, males peck at or lock bills with each other. While squabbling over territory or chasing away nest intruders, they may dive and swoop through dense vegetation, sometimes hitting branches along the way. Males may also defend small sites around bird feeders in the winter, though females seem to use alternative feeding sites to avoid competition. Varied Thrushes are thought to establish monogamous breeding pairs, but how long the birds stay together is not known. Back to top

    Conservation

    Conservation Common Bird in Steep DeclineVaried Thrushes are fairly common, but populations declined by over 2.5% per year between 1966 and 2015, resulting in a cumulative decline of 73%, according to the North American Breeding Bird Survey. Partners in Flight estimates a global breeding population of 20 million with 82% spending some part of the year in the U.S., 32% in Canada, and 3% wintering in Mexico. The species rates an 12 out of 20 on the Continental Concern Score. Varied Thrush is not on the 2016 State of North America's Birds' Watch List, but the 2014 State of the Birds Report lists it as a Common Bird in Steep Decline. It is a a U.S.-Canada Stewardship species. Because Varied Thrush live in mature and old-growth forests containing very large trees, logging and forest fragmentation can cause habitat loss that reduces their numbers. These birds don’t tend to live in forest patches smaller than about 40 acres. Around human habitation, Varied Thrushes have proven very vulnerable to window strikes as well as predation by domestic and feral cats and collisions with cars. Varied Thrushes may benefit from reserves that have been established to protect the Northern Spotted Owl.Back to top

    Backyard Tips

    In the winter Varied Thrushes will eat seed from ground feeders. Planting native fruiting shrubs is also a good way to attract them to your yard. Find out more about what this bird likes to eat and what feeder is best by using the Project FeederWatch Common Feeder Birds bird list.

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    Credits

    George, T. Luke. 2000. Varied Thrush (Ixoreus naevius), version 2.0. In The Birds of North America (P. G. Rodewald, editor). Cornell Lab of Ornithology, Ithaca, New York, USA.

    Lutmerding, J. A. and A. S. Love. Longevity records of North American birds. Version 2015.2. Patuxent Wildlife Research Center, Bird Banding Laboratory 2015.

    North American Bird Conservation Initiative. 2014. The State of the Birds 2014 Report. US Department of Interior, Washington, DC, USA.

    Partners in Flight. 2017. Avian Conservation Assessment Database. 2017.

    Sauer, J. R., D. K. Niven, J. E. Hines, Jr. Ziolkowski, D. J., K. L. Pardieck, J. E. Fallon and W. A. Link. The North American breeding bird survey, results and analysis 1966-2015 (Version 2.07.2017). USGS Patuxent Wildlife Research Center 2017.

    Sibley, David Allen. 2014. The Sibley guide to birds, second edition. Alfred A Knopf, New York.

    Wells, J. V., K. V. Rosenberg, D. L. Tessagalia and A. A. Dhondt. 1996a. Population cycles in the Varied Thrush (Ixoreus naevius). Can. J. Zool. no. 74:2062-2069.

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