Focus on the Scarlet Tanager

The Scarlet Tanager is a vibrant symbol of Pennsylvania’s forest. Indeed it has been used as part of the logo for the State’s Wildlife Action Plan because is so characteristic of the state’s principal wildlife habitat – the forest.  It has been estimated that our state may contain a whopping 17% of the world’s population of this colorful migratory songbird.  Did we mention that the Scarlet Tanager really is scarlet?  At least the males on their breeding ground are a very bright red and one of the most stunning birds on the continent.  However, it is often hard to see that bright red in the dappled darkness of a forest.  If you do not see it, you can also hear a male Scarlet Tanager’s burry warbling song which starts in the pre-dawn and can continue even in the afternoon and evening hours.  Scarlet Tanagers prefer forests with trees over 50 feet high and high canopy cover, but can thrive where there are small gaps in the forest from tree fall, rocks, and natural or artificial disturbances.  The Scarlet Tanager is emblematic of the state’s expansive forest and its links with exotic locations through the miracle of migration.

CURRENT STATUS: In Pennsylvania, the Scarlet Tanager is listed under Species of Greatest Conservation Need.  In the first Wildlife Action Plan, it was categorized as a “Responsibility Species” because our state has approximately in the State Wildlife Action Plan. This forest interior songbird is protected under the federal Migratory Bird Treaty Act of 1918.

Acadian Flycatcher, often in quality riparian forests, by Jacob Dingel, PGC

POPULATION TREND: Across the state, the Scarlet Tanager has declined at a rate of 1% per year according to Breeding Bird Surveys. Pennsylvania is very important to the future of scarlet tanager. Approximately 60% of “Penn’s Woods” is covered by forest so it is not surprising that the state has been estimated to have as much as 17% of the world’s nesting scarlet tanager population, a higher percentage than for any other bird species. Therefore, the state has a high stewardship responsibility for the future of this brilliant migratory forest songbird and its cohorts. It is imperative that the commonwealth manage its forests in such a way as to retain healthy populations of this beautiful and appealing songbird for the enjoyment of future generations.

Fortunately, the population trend of Scarlet Tanager seem to be fairly stable and the species has shown some resiliency. Established bird monitoring programs such as the Breeding Bird Survey and eBird track the population of this conspicuous bird fairly well. Participation by the state’s birding community in these and other  “citizen science” projects should continue and expand as threats to forests increase.

Male Hooded Warbler by Jake Dingel

IDENTIFYING CHARACTERISTICS: Eminently tropical birds, the male scarlet tanagers are a deep, bright red with contrasting black wings and tail. In the sun, a male scarlet tanager looks a brilliant torch of bright feathers, but can be amazingly well-hidden in its shady forest haunts. Although the male’s plumage stands out against the green leafy backdrop, it is often concealed in the shade and density of the canopy. The female, with its overall yellowish-green plumage blends perfectly with tree foliage under all lighting conditions. Females are very difficult to detect as they move slowly through the leaves and branches foraging for insects. Occasionally, male scarlet tanagers are orange-colored rather than brilliant red. Although they retain their black wings and tail, wintering male tanagers are far less showy in their winter plumage. After a late summer molt, male tanagers are yellowish-green, much like the female’s overall color. When they first return from the south in spring, many males look very odd because they are still speckled with some green feathers.

Pennsylvania has great stewardship responsibility for the beautiful Scarlet Tanager, photo by Jake Dingel

BIOLOGY-NATURAL HISTORY: In spring and summer the tanager’s song and call often reveal its location high in the trees. Its whistled song is a series of burry, robin-like, phrases with a diagnostic “chick-burr” call. They dip and raise their tail during the frequently given “chick-burr.” Males and females also call back and forth with a soft “sweee” call.

During late April and early May, when males claim or reclaim a breeding territory, the male finds a prominent perch and sings almost constantly from this high point to claim and defend the territory. Female tanagers sometimes answer in a short, softer version of the song. Males counter-sing back and forth between adjacent territories, especially in early morning.

Female tanagers build their nest at various heights but most often between twenty and forty feet above ground. She constructs a flimsy, somewhat bulky nest in the forked branches of a horizontal or nearly horizontal limb. The nest is made of twigs, grass, bark strips and weeds with finer plant material used for lining. A tanager nest is usually shielded by a hanging leaf cluster or hidden in a vine. The female tanager also does the incubating, two to five eggs, while the male forages and brings her food. Both adults feed the young. Pairs are only have a single brood each year.

Scarlet tanagers eat spiders and insects. They will hawk for flying insects, although they mostly glean and snatch prey while foraging branches and leaves, sometimes hovering to thoroughly inspect a leaf or to reach an insect. Prey includes beetles and beetle larvae, bees and wasps, moths, caterpillars, dragonflies, snails, millipedes and worms. Tanagers will also eat buds and fruits, and grab earthworms off the ground. They forage a lot in the mid-story and canopy among the heavy foliage of the forest. In late summer and fall, tanagers also forage on wild fruits and berries.

In mid to late summer, after nesting, adult Scarlet Tanagers and young birds wander widely beyond breeding territories until September and early October when this neotropical migratory bird leaves Pennsylvania and northeast North America and travels south from Panama to South America. Some scarlet tanagers travel over 4,000 miles from breeding grounds to wintering grounds. These long-distant migrants spend the winter with many other tanager species and a few other North American songbirds in the remote forests of Columbia, Ecuador, Peru and Bolivia. On these wintering grounds the forest habitat holds more thick brush and scrub than that found on their breeding habitat in North America.

Wood Thrush by Jacob Dingel, PGC.

PREFERRED HABITAT: The scarlet tanager is a forest interior bird that lives in mixed forests and large woodlands, especially mature forests, but can be found in pine stands, upland deciduous woods, wooded ravines and small patches of forest. Tanagers are commonly found in oak and hickory forests, but also are found in a variety of mixed forests including extensive conifer forests at all elevations.  Scarlet Tanagers can be fairly common in Pennsylvania’s forests including our game lands, state parks, and state forests.  They prefer more mature forests with tall trees, high canopy cover, and a healthy mid-story of small trees, saplings, and shrubs.  They are among the most abundant species in Pennsylvania’s woods but often are not detected unless they are heard. The male scarlet tanager is one of Pennsylvania’s most brilliantly colored songbirds and yet it is often overlooked because it inhabits treetops and the forest canopy.  Many of the forested Important Bird Areas of the state support large populations of Scarlet Tanagers.

Black-throated Blue Warbler male by Jake Dingel

REASONS FOR BEING LISTED: Pennsylvania has a high stewardship responsibility for this species, estimated to include 13 to 17 percent of its global population.  As a largely forested state, Pennsylvania supports a higher proportion of the population of this species than any other bird species.  Therefore, it has high stewardship responsibility for the future of this spectacularly attractive bird and it is listed as a Responsibility Species in the Wildlife Action Plan.  This forest interior songbird relies on contiguous forest canopy or large forest tracts that are connected to other sizable forest tracts. The scarlet tanager’s abundance and nesting success decline in fragmented and perforated forests. This species also experiences a higher rate of brood parasitism by Brown-headed Cowbirds (Monothrus ater) in smaller woodlots.  The primary effect of cowbird nest parasitism is the removal of tanager eggs from the nest which reduces productivity of the tanager pair.  A fragmented forest provides less interior forest habitat and creates more edge habitat and openings. The occurrence of scarlet tanagers appears to be negatively correlated with the degree of fragmentation and the amount of edge in the landscape.  In Pennsylvania, valuable interior forest habitat is being lost, altered and degraded on a large scale with the cumulative impact of urban and residential development and wind and gas energy development. This neotropical migrant songbird faces habitat loss along its migration route and on wintering grounds as well.  Collisions with towers and buildings in migration, condition of stopover habitats, and the state of its winter habitat in South America are additional threats to this migratory species.

Kentucky Warbler thrives in forests with a healthy shrub and ground vegetation cover, by Jacob Dingel, PGC

MANAGEMENT PROGRAMS: Scarlet tanagers primarily live in fairly mature deciduous and mixed deciduous – coniferous forests. Managing Pennsylvania forests to minimize fragmentation is crucial to interior forest songbird species such as the scarlet tanager. It is much easier to protect large forest blocks than to create them.  In Pennsylvania, scarlet tanagers are not as area-sensitive as elsewhere in their range so there are opportunities for pro-active management even on a smaller scale.  A well-stratified forest structure with a shrub, sapling, and herbaceous layer also is beneficial to foliage-gleaning insectivorous birds like tanagers.  Management practices that promote the long-term presence of healthy forest patches that are connected to each other will benefit the scarlet tanager and its cohorts.  Other species that tend to be associated with scarlet tanagers include Eastern Wood-Pewee, Wood Thrush, Ovenbird, Louisiana Waterthrush, Worm-eating Warbler, Cerulean Warbler, Black-throated Blue Warbler, Black-throated Green Warbler, and other species considered priorities for bird conservation. Three of these: Worm-eating Warbler, Cerulean Warbler, Black-throated Blue Warbler, are national Watch List species. Managing for the conspicuous and charismatic scarlet tanager, therefore, benefits other species that may not be as recognized or supported by the public.

Eastern Wood-Pewee, a common forest species often found with Scarlet Tanager, by Jacob Dingel, PGC

To learn more about the Pennsylvania Wildlife Action Plan, and its significant role in conservation, as well as State and Tribal Wildlife Grant projects within Pennsylvania, visit the Game Commission’s website at www.pgc.pa.gov and the Pennsylvania Fish and Boat Commission’s website at www.fishandboat.com.

Pennsylvania Wildlife Action Plan Logo, 2015

Sources:

Fraser, G. and Stutchbury, B. J. M. 2004. Area-sensitive birds move extensively among forest patches. Biological Conservation 118: 377-387.

Gouguen, C. B. 2010. Scarlet Tanager, Piranga olivacea, pages 182-185, In Terrestrial Vertebrates of Pennsylvania: A Complete Guide to Species of Conservation Concern. The Johns Hopkins University Press, Baltimore, Maryland.

Lambert, J. D., B. Leonardi, G. Winant, C. Harding, and L. Reitsma. 2017. Guidelines for managing wood thrush and scarlet tanager habitat in the Northeast and Mid-Atlantic regions. High Branch Conservation Services, Hartland, Vermont.

McWilliams, G. M. and D. W. Brauning. 2000. The Birds of Pennsylvania. Cornell University Press, Ithaca, New York.

Mowbray, T. B. 1999. Scarlet Tanager, Piranga olivacea, In Birds of North America, No. 479 (A. Poole and F. Gill, eds.). The Birds of North America Inc., Philadelphia, Pennsylvania.

Pennsylvania Game Commission and Pennsylvania Fish and Boat Commission. 2005. State Wildlife Action Plan. Harrisburg, Pennsylvania.

Pennsylvania Game Commission and Pennsylvania Fish & Boat Commission. 2015. Pennsylvania Wildlife Action Plan, 2015-2025. C. Haffner and D. Day, editors. Pennsylvania Game Commission and Pennsylvania Fish & Boat Commission, Harrisburg, Pennsylvania.

Roberts, C., and C. J. Norment, 1999. Effects of plot size and habitat characteristics on breeding success of scarlet tanagers. Auk 116:73-82. http://elibrary.unm.edu/sora/Auk/v116n01/p0073-p0082.pdf (New York)

Rosenberg, K.V., R.W. Rohrbaugh, Jr., S.E. Barker, J.D. Lowe, R.S. Hames, and A.A. Dhondt. 1999. A land managers guide to improving habitat for scarlet tanagers and other forest-interior birds. The Cornell Lab of Ornithology, Cornell University, Ithaca, New York.

Stutchbury, B. J. M. 2007. Silence of the Songbirds. HarperCollins, Toronto, Canada.

Stutchbury, B. J. M. 2012. Scarlet Tanager, Piranga olivacea, pages 430-431, In Second Atlas of Breeding Birds in Pennsylvania. (A. M. Wilson, D. W. Brauning, and R. S. Mulvihill, Eds.). The Pennsylvania State University Press, University Park, Pennsylvania.

Worm-eating Warbler, commonly found in oak forests with Scarlet Tanager, by Gerry Dewaghe