Western tanagers are about 18 cm long and weigh about 28 grams. They have a wingspan of about 28 to 30 cm, with rounded wings and a fan-shaped tail. They use their beak for catching food, building nests, preening, digging holes, and caring for their young. Their eyes are sepia brown in young birds, grayish brown or black in adult males, and reddish brown to burnt umber in adult females. Among males, their breast is mostly yellow, their back and wings are mostly black, and their entire head is red. Their wings have two bright yellow wing bars. Females are pale in comparison, with an olive green upper back and head. Their wings are grey with two wing bars and their tails are greyish brown or olive green. After hatching, young have white or pale gray down on their head, back, and wings, and their wing bars become visible after 10 days. (Hudon, 1999; "Western Tanager", 2013)
Western tanagers follow the forests ranging from the western coasts of North America and Central America from Alaska to Panama. This area stretches as far east as the Northwest Territories in Canada and the western edge of North Dakota, Nebraska, and Texas. Their main breeding territory is in the far northern region of Canada and they migrate south during the winter. However, they have been known to breed in their wintering regions of South America. (Meyer, 2006; Monroy-Ojeda, et al., 2013)
Western tanagers arrive in their breeding grounds in the spring and breed in open coniferous forests and mixed woodlands. They leave their northern habitats in late summer and spend the winters in open mountain pine woodlands, parks, gardens, desert oases, near lakes, and orchards. In their wintering range, they live in pine and pine-oak woodlands as well as low-canopied scrub forests. They have been seen in elevations as high as 10,000 feet and as low as 330 feet. (Meyer, 2006)
Western tanagers are monogamous, meaning that males and females pair up and mostly only mate within their pair. Pairs form during migration or on the wintering grounds, mostly in South America. Pairs that form on the wintering grounds may migrate together to the breeding grounds. Males find and defend their territory by singing and chasing others away. However, males are not known to perform any displays to attract mates. (Hudon, 1999; Meyer, 2006)
The earliest birds may arrive on the breeding grounds in April, while most birds arrive by early May. On average, females and first-year males arrive at breeding grounds later. Both males and females are sexually mature after two years. Although western tanagers are socially monogamous, males may move outside the territory they defend to mate with other females. Females build small cup-like nests from grass and twigs in about 4 to 5 days. Males feed the females during the nest building and the egg laying process. On average, the eggs are 23 mm long, about 3.35 grams, and are pale blue or bluish green. The eggs are blotched with brownish speckles that form a thick wreath around the larger end of the egg. Females lay around 3 to 5 eggs, which takes about a day per egg. The eggs are incubated by the female for around 13 days. The young are fed by both parents and fledge within 15 days. The young do not become independent until about two weeks after fledging. Western tanagers may leave their breeding grounds as early as July, but usually do not begin migration until August. (Davis, 2001; Hudon, 1999; Meyer, 2006)
Female western tanagers incubate the eggs alone, but both parents feed the young. They even continue feeding the fledglings for about two weeks after they have left the nest. The young are known to stay on the breeding grounds even after the adults have left. (Hudon, 1999; Meyer, 2006)
Western tanagers have been known to live up to 15.3 years, but their average life span is around 8 years. These birds commonly die due to predation or lack of food. (Hudon, 1999; Lee, 2012; Magalhaes, 2012)
Western tanagers migrate long distances and migrate alone, in pairs, or in groups of about 30. They migrate at night at very high altitudes. They form loose associations with other bird species such as Townsend's warblers, purple finches, and mountain chickadees. Males chase other males that intrude in their territory and females chase other females. They also charge at smaller birds. Western tanagers can be difficult to see because they forage in the upper branches of trees and move slowly, but in flight they are swift and direct. (Hudon, 1999; Meyer, 2006)
There are a few studies of home territories for western tanagers. A conifer forest in Idaho averaged a home range size of 39,100 square meters, while in Montana; they have an average home range of 28,300 square meters. (Davis, 2001; Samuel, et al., 1985)
Western tanagers mostly communicate through song. Their song sounds similar to American robins', but pauses after each phrase and sounds more hoarse. Their calls are short and explosive and used by both males and females and their young. The young sound more musical, while the female is less eloquent. Her song is more repetitive, with an average of 2 to 5 phrases. Males have more articulated and more frequent vocalizations, with 4 to 7 song phrases. Males mostly sing while they are on the breeding grounds. Males are attracted to the playback of female songs and will also counter-sing when they hear neighboring males. These birds mostly sing in the morning. When a female feels threatened, she gives a series of nervous calls. When the male hears the nervous call of his mate, he gives a loud series of nervous calls and flies from branch to branch. (Hudon, 1999; Stalling, 2012)
Western tanagers are insectivores and catch insects while they are in flight. Vespid wasps are not eaten by other migratory birds, but are often preferred by western tanagers. They also eat fruits and nectar from plants. During the winter they eat both insects and fruit. (Carlise, et al., 2012; Hudon, 1999)
There are several birds that prey on western tanagers. Common predators are hawks, owls, and jays. Nest predators include owls, jays, black bears, prairie rattlesnakes, bull snakes, common ravens, American crows, squirrels, and even domestic cats. When they see a predator, western tanagers cock their tail, flap their wings, and make loud nervous calls. When a predator comes too close to their nest, western tanagers swoop towards the intruders. (Hudon, 1999; Meyer, 2006)
Western tanagers are prey for many birds and mammals. Brown-headed cowbirds are known to parasitize western tanager nests and also reduce the number of western tanagers that are able to fledge per nest by knocking western tanager eggs out of their nests and laying their own eggs in their place. Western tanagers are known to mob cowbirds, but cowbirds are often successful. After hatching, western tanagers will raise the cowbirds until they fledge. Blowfly larvae are also known to parasitize fledgling western tanagers. (Davis, 2001; Hudon, 1999; Meyer, 2006)
There are no known negative effects of western tanagers on humans.
Western tanagers are known to eat several insects and are viewed as a form of pest control for humans. (Hudon, 1999)
Western tanagers are not threatened, in fact, the species has a large range. Western tanagers are protected under the U.S. Migratory Bird Act. (Birdlife International, 2012)
Western tanagers have a red pigment on their faces caused by rhodoxanthin, a pigment that is very rare in birds. This pigmentation comes from the insects western tanagers eat, and the insects get it from plants. (Hudon, 1991; Hudon, 1999)
Jeneil Boles (author), University of Wyoming, Hayley Lanier (editor), University of Wyoming - Casper, Leila Siciliano Martina (editor), Animal Diversity Web Staff.
The Cornell Lab of Ornithology. 2013. "Western Tanager" (On-line). All About Birds. Accessed November 24, 2013 at http://www.allaboutbirds.org/guide/western_tanager/id.
Carlise, J., K. Olmstead, C. Richart, D. Swanson. 2012. Food availability, foraging behavior, and diet of autumn migrant landbirds in the Boise Foothills of Southwestern Idaho. The Condor, 114.3: 449-461.
Davis, C. 2001. "California Partners in Flight Coniferous Bird Conservation Plan for the Western Tanager (Piranga ludoviciana)" (On-line). Accessed November 01, 2013 at http://www.prbo.org/calpif/htmldocs/species/conifer/wetacct.html.
Hudon, J. 1999. The Birds of North America. Philadelphia, PA: The Academy of Natural Sciences.
Hudon, J. 1991. Unusual carotenoid use by the western tanager (Piranaga ludoviciana) and its evolutionary implications. Canadian Journal of Zoology, 69: 2311-2320.
Lee, V. 2012. "Western Tanager Tags: Birds, Through the Looking Glass of Val Lee" (On-line). Accessed November 02, 2013 at http://birdsbyval.wordpress.com/2012/04/07/through-the-looking-glass-of-val-lee-western-tanager/.
Magalhaes, J. 2012. "AnAge entry for Piranga ludoviciana" (On-line). The Animal Aging and Longevity Database. Accessed November 13, 2013 at http://genomics.senescence.info/species/entry.php?species=Piranga_ludoviciana.
Meyer, R. 2006. "Fire Effects Information System" (On-line). Accessed November 04, 2013 at http://www.fs.fed.us/database/feis/.
Monroy-Ojeda, A., M. Grosselet, G. Ruiz, E. Del Valle. 2013. Winter site fidelity and winter residency of six migratory neotropical species in Mexico. The Wilson Journal of Ornithology, 125.1: 192 -196.
Samuel, M., D. Pierce, E. Garton. 1985. Identifying areas of concentrated use within the home range. Journal of Animal Ecology, 54: 711-719.
Stalling, D. 2012. "Montana Outdoors Portrait: Western Tanager Piranga ludoviciana" (On-line). Accessed November 04, 2013 at http://fwp.mt.gov/mtoutdoors/HTML/articles/portraits/2012/westerntanager.htm#.UniHkfmsj5w.