Hermit thrushes are shorter and stockier than other spotted thrushes, with an average length of 6.75 in (17.2 cm) and wingspan of 11.5 in (29.2 cm). The three main geographic groups have graded characteristics, with a distinct white eye-ring, indistinct whitish bar over the lores, darkly spotted breast and sides of the throat, olive-brown to gray-brown dorsal coloration, white ventral side with buffy to grayish flanks, and varying amount of reddish wash on flight feathers and tail. There is no obvious sexual dimorphism in this thrush species.
Hermit thrushes have reddish coloration on the tail, whereas wood thrushes (Hylocichla mustelina) have similar coloration on the head and veery (Catharus fuscescens) have reddish upper parts. Gray-cheeked (Catharus minimus) and Bicknell's (Catharus bicknelli) thrushes also have some reddish coloration, but they only have a thin partial eye-ring and do not have the whitish bar over the lores. Because hermit thrushes are short-distance migrants, their primary flight feathers do not project beyond their secondaries. Other thrushes that migrate over longer distances have longer primary projections, including the Swainson's thrush (Catharus ustulatus) and grey-cheeked thrush (Catharus minimus). (Elphick, et al., 2001; Sibley, 2000)
Hermit thrushes (Catharus guttatus) are widely distributed songbirds found in northern hardwood forests and boreal and mountainous coniferous forests throughout North America during the breeding season, and both North America and Central America during the winter. In North America, they breed in the western and northeastern United States into Alaska and much of the southern half of Canada. The winter northern boundary is in the United States from southern Massachusetts moving gradually southwest to the southern parts of Ohio, Indiana, Illinois, Arkansas, most of Oklahoma and Texas. Their winter range then encompasses all of the area below this to the Gulf of Mexico and then south through Mexico to Oaxaca. They are found year round in much of New Mexico and in the eastern half of Arizona. Within these broad ranges individuals are short-distance migrants. They do not cross the Gulf of Mexico as other Catharus species do. They are found in lower altitudes, river valleys and coastal areas in these wintering areas.
There are currently 8 recognized subspecies of hermit thrushes divided into 3 geographic groups including 3 subspecies in the Pacific coastal group, 3 subspecies in the northwestern interior mountains group, and 2 subspecies in the eastern group. (Ehrlich, et al., 1988; Jones and Donovan, 1996)
Hermit thrushes use a wide range of forest vegetation types. Breeding habitat includes young to climax forest vegetation types with internal forest edges. These birds are found in the interior of such forest vegetation types near openings including ponds, meadows, or small man-made clearings.
During winter in the United States, hermit thrushes are usually found at lower elevations than that of their summer habitat. Characteristics of winter habitat include a dense cover of woody plants proximate to insect populations and berry-bearing vegetation. Hermit thrushes need open water in their winter habitat. Information on habitat in Mexico is limited, and no generalizations can be made. (Ehrlich, et al., 1988; Elphick, et al., 2001; Jones and Donovan, 1996)
Males establish and defend breeding territories in late April to late May. Once a female is accepted into a male's territory, she begins building a nest. The open-cup nest is 10 to 15 cm in diameter and consists of a variety of vegetable material including grass, leaves, mosses, and lichens. Nest location is variable. In the eastern United States nests found on the ground beneath live woody and non-woody plants and in open areas, and in the western United States nests were commonly located above the ground. Females lay 3 to 6 eggs beginning in Late May, and may lay 2nd or 3rd brood as late as August. Egg color ranges from very pale blue to blue-green with few brown flecks. Females begin incubating after final egg is laid, and this period lasts around 12 days. The male feeds the female during incubation.
A hatching bird "pips" the egg, breaks its shell into 2 parts near the egg's greatest diameter. The female removes eggshells from the nest after young hatch. Young are altricial at hatching and have minimal dark grayish down on crown and dorsal feather tracts. The female feeds nestlings with food brought to the nest by the male. Nestling eyes are open by the 3rd day after hatching; full juvenile plumage develops by 10 to 12 days after hatching. Nestlings fledge 10 to 15 days after hatching by leaping from the nest towards a parent on the ground. No information on development from fledging through immature stages is available.
Brood parasitism by the brown-headed cowbird is common, but little is known on how this affects populations of the Hermit Thrush. Recruitment may be limited by nest predation, but little information is available. Studies estimating the probability of fledging at least 1 nestling varied from 17% in Arizona to 37% East of the Rocky Mountains. There is no evidence of cooperative breeding in hermit thrushes. (Ehrlich, et al., 1988; Elphick, et al., 2001; Jones and Donovan, 1996)
Females incubate and deliver food to the nestlings. Males bring food to the nest.
A banded hermit thrush lived at least 8 years and 8 months. Other thrushes have been known to live 10 to 13 years. (USGS Patuxent Wildlife Research Center, 2002)
Hermit thrushes can be distinguished from other similar thrushes in the field not only by their song, but also by other distinctive behaviors including tail- and wing-flicking. When a bird lands, it may quickly raise and then slowly lower its tail. It also makes a distinctive "tchup" call when doing this. When perched, hermit thrushes will extend their wings out from their bodies very rapidly and then immediately return them to their sides.
Males are territorial during breeding and winter seasons. Males arrive on breeding grounds before females and establish territories. Males initially display hostile behavior when a female first enters the territory, but after 3 to 4 days of developing courtship flight, they accept the female. Territoriality on wintering grounds likely results from competition for food and cover. Agonistic displays include gaping, crest raising, horizontal stretching, and bill snapping. (Brown, et al., 2000; Jones and Donovan, 1996)
Hermit thrushes are omnivores that eats insects, small invertebrates, and fruits from trees, shrubs, and herbaceous plants. They forage on both the ground and in vegetation, and may move leaf litter with their bills to look for food, glean from leaves while perched or after hovering, or probe into ground or dead wood. The proportion of animal and vegetable content in the diet of Hermit Thrushes varies with availability. Generally, hermit thrushes consume more animal matter during the spring and summer, and more vegetable matter (especially berries) in the fall and winter.
Foods commonly eaten include: beetles, bees, ants, wasps, flies, true bugs, other small invertebrates, small amphibians and reptiles, and fruits. (Jones and Donovan, 1996)
There is little information on predation but they probably are subject to the usual songbird nest predators (snakes, crows, jays, raccoons). Body parasites found on or in adult hermit thrushes include lice, louse flies, mites, spirochetes and ticks. (Jones and Donovan, 1996)
There are no known adverse effects of Hermit Thrushes on humans.
Breeding Bird Surveys indicate that hermit thrush populations have increased over extensive parts of their range. (Elphick, et al., 2001)
The name Catharus derives from the Greek word katharos or "pure" referring to its song. The name guttatus comes from gutata or "spotted", for its spotted breast. (Wells, 2002)
Catherine Blasch (author), University of Arizona, Todd McWhorter (editor), University of Arizona.
Brown, D., P. Stouffer, S. Strong. 2000. Movement and territoriality of wintering hermit thrushes in Southeastern Louisiana. Wilson Bulletin, 112: 347-353.
Ehrlich, P., D. Dobkin, D. Wheye. 1988. The Birders Handbook: a Field Guide to the Natural History of North American Birds. New York, New York: Simon and Schuster Inc..
Elphick, C., J. Dunning, D. Sibley. 2001. The Sibley Guide to Bird Life and Behavior. New York, New York: Alfred A. Knopf, Inc..
Jones, P., T. Donovan. 1996. Hermit Thrush (Catharus guttatus). Pp. 1-28 in A Poole, F Bill, eds. The Birds of North America. Philadelphia and Washington D.C.: Academy of Natural Sciences and American Ornithologists' Union.
Rivers, J., D. Kroodsma. 2000. Singing behavior of the hermit thrush. Journal of Field Ornithology, 71: 467-471.
Sibley, D. 2000. National Audubon Society: The Sibley Guide to Birds. New York: Chanticleer Press, Inc..
USGS Patuxent Wildlife Research Center, 2002. "Longevity records of North American birds" (On-line). Accessed 30 July 2002 at http://www.pwrc.usgs.gov/bbl/homepage/longvrec.htm.
Wells, D. 2002. 100 Birds and How They Got Their Names. New York, New York: Workman Publishing.