Western tanager
The western tanager, is a medium-sized American songbird. Formerly placed in the tanager family, it and other members of its genus are classified in the cardinal family. The species's plumage and vocalizations are similar to other members of the cardinal family.
Taxonomy
The western tanager was illustrated and formally described by American ornithologist Alexander Wilson in 1811 under the binomial name Tanagra ludoviciana from a specimen collected on the Lewis and Clark Expedition. The type locality is Kamiah, Idaho. The specific epithet is from the Late Latin ludovicianus for "Louis". The name is from Louisiana, the 18th-century French administrative district of New France, rather than the modern state. The western tanager is now placed in the genus Piranga that was introduced by French ornithologist Louis Pierre Vieillot in 1808. The species is monotypic; no subspecies are recognized.Description
Measurements:- Length: 6.3–7.5 in
- Weight: 0.8–1.3 oz
- Wingspan: 11.5 in
The song of disconnected short phrases suggests an American robin's, but is hoarser and rather monotonous. The call is described as pit-er-ick.
Their breeding habitat is coniferous or mixed woods across western North America from the Mexico-U.S. border as far north as southern Alaska; thus, they are the northernmost-breeding tanager. They build a flimsy cup nest on a horizontal tree branch, usually in a conifer. They lay four bluish-green eggs with brown spots.
These birds migrate, wintering from central Mexico to Costa Rica. Some also winter in Southern California.
Distribution and habitat
The breeding range of the western tanager includes forests along the western coast of North America from southeastern Alaska south to northern Baja California, Mexico. Western tanagers extend east to western Texas and north through central New Mexico, central Colorado, extreme northwest Nebraska, and areas of western South Dakota to southern Northwest Territories, Canada. The western tanager's wintering range stretches from central Costa Rica north through Nicaragua, Honduras, El Salvador, and Guatemala to southern Baja California Sur and extreme southeastern Sonora in western Mexico and to southern Tamaulipas in northeastern Mexico. Western tanagers do not typically occur in the Caribbean lowlands. They have been reported wintering further north and have been observed as far south as Panama. Vagrants are rare to casual in the eastern United States.In addition to the plant communities listed above, western tanagers are reported from disturbed habitats. For instance, western tanagers were seen in an area of northwestern California that had been logged less than five years previously. Cutleaf burnweed was characteristic of the youngest age class, while slightly older sites were composed predominantly of tanoak with smaller amounts of snowbrush ceanothus, whitebark raspberry, and Sierra gooseberry. In addition, western tanagers were captured along the Rio Grande in New Mexico during spring and fall migration in an agricultural area composed primarily of alfalfa and corn.
Western tanagers have also been observed in saltcedar communities and in Russian olive vegetation. In New Mexico, western tanagers were observed in nearly pure stands of saltcedar 10 to 23 ft tall. Western tanagers were also observed in saltcedar communities during fall migration in along the Rio Grande. Ten western tanagers were observed among three sites composed of Russian olive in Colorado, Utah, and Idaho. All sites were dominated by Russian olive with cheatgrass comprising a substantial portion of the understory. Along the Rio Grande, western tanagers were most often captured during fall migration in vegetation with a Rio Grande cottonwood overstory and a moderate to dense Russian olive understory.
Behavior and ecology
Western tanagers migrate alone or in groups of up to 30 birds. On average, hatching-year western tanagers were captured later at Rio Grande Nature Center than adult western tanagers during fall migration. Migration timing, condition of birds, and site differences in spring and fall migration were also addressed in this investigation.Breeding
Western tanagers arrive on their breeding grounds in spring. Breeding usually occurs among birds two years or older, beginning in May and continuing into July, although some first-year western tanagers also breed. In the Sandia Mountains of north-central New Mexico, western tanagers were heard singing beginning in late May, and the first nest was found in early June. In public open-space areas in Boulder County, Colorado, the start of the western tanager breeding season was estimated as 28 May, and the peak of the breeding season, defined as at least 50% of western tanager nests active, was from 6 June to 1 July. In the Southwest, brooding generally begins in early May, while in the Northwest, brooding starts typically in mid-June. Brooding can begin earlier in British Columbia and Alberta than in the northwestern United States. An egg-laying date as early as 16 May in British Columbia was estimated by back calculation, and a complete egg set was observed as early as 26 May in Alberta.Cup nests are built by the female, take about four or more days to construct, and are made from twigs, rootlets, grasses, and pine needles. No evidence has been found for second broods in western tanagers, but a review notes a nesting attempt after a failed nest in west-central Idaho, and suggests that renesting is a substantial source of late nesting attempts. In addition, renesting was suggested as the explanation for a few late nests observed in Boulder County, Colorado.
Clutch size is typically three to five eggs. Average clutch size in 10 nonparasitized nests in Boulder County was 3.8 eggs. Average clutch in the Southwest may be smaller than that of western tanagers nesting in the north. Egglaying generally takes about one day per egg. The female incubates the eggs for about 13 days, although shorter incubation periods have been reported. The young are fed by both parents, and typically fledge 11 to 15 days after hatching. Immature western tanagers have been observed with the parents at least two weeks after fledging.
Immature western tanagers initiate migration later than adult birds. Generally, western tanagers leave more northerly locations in late summer or early fall, while those in more southerly areas may stay as late as early November.
Reproductive success of western tanagers varies widely between studies and across years. An average annual nest success probability estimate is 0.186 over 3 years, with a low of 0.035 and a high of 0.349. In a northern Arizona study area, an average of 43% of nests succeeded to the nestling stage. In Boulder County, nesting success varied from 11.3% to 75.3%, with an average of 51.8% over a 3-year period. Daily nest survival rate on ungrazed sites in northeastern New Mexico was 0.955, which was not significantly different from the 0.973 daily nest survival rate found on grazed sites. Nest predation is the leading cause of nest failure. Predation rates ranged from 30% in a study in New Mexico pinyon-juniper woodland to 86% in a mixed-conifer forest in Idaho.
Western tanagers can live several years. The annual average survival rate is 0.753 and a return rate is 30.1% for western tanagers in west-central Idaho. A wild western tanager 7 years and 11 months old has been documented from banding data.
Habitat
During the breeding season, western tanagers are found primarily in relatively open coniferous forests and mixed woodlands. During migration, western tanagers occur in more areas, including lowland woodlands of Southern California, desert oases, riparian areas, parks, and orchards. In the western tanager's wintering range, it occupies pine and pine-oak woodlands, as well as low-canopied scrub forests, forest edges, and coffee plantations.Western tanagers breed at a wide range of elevations from about 183 ft in the Northwest up to 10,000 ft. In the northern portion of their breeding range, western tanagers have been observed on sites over 8,300 ft in Oregon down to sites as low as 183 ft in Oregon's Central Willamette Valley. In the southern portion of their breeding range, western tanagers are more typical on high-elevation sites. They were observed on an Arizona site 8,270 ft in elevation and on a site at 9,500 ft in Nevada.
Nesting
Western tanagers nest in second-growth and mature conifer and mixed forests. They only breed in stands of pole- to large-sized trees and stands of pole- to medium-sized trees with >70% canopy cover. Nesting was confined to older second-growth and mature Douglas fir communities in the western Cascade Range in Oregon.Western tanager nests are typically found in coniferous trees toward the end of horizontal branches and at heights greater than 10 ft ; 79% of 43 western tanager nests in British Columbia were found in conifers, primarily Douglas fir. The deciduous trees most often used were quaking aspen and willows. The position of their nests along the branches of deciduous trees was more variable than in conifers. On this site, 56% of nests were at heights from 21 to 36 ft. Of 9 western tanager nests in an Alberta study site, eight occurred in white spruce and one was found in quaking aspen. Nest height ranged from 20 to 42 ft, with a mean of about 30 ft. On average, nests were located 80% of the distance from the trunk to the tip of the branch. Of 49 western tanager nests found in a pinyon-juniper woodland in northeastern New Mexico, 98% were in Colorado pinyon and the remainder occurred in Douglas fir. On this site, nest trees averaged 24 ft in height and over 8 in in diameter at breast height. The average height of nests was 18 ft. In a nearby mixed-conifer forest, nests were found in Douglas fir and ponderosa pine. Nest trees on this site averaged nearly 50 ft in height and 13 in in dbh. The average nest height was 16 ft and on average nests were located about 5 ft from the tree stem and 3 ft from the edge of the tree's foliage. Western tanager nests on a north-central New Mexico site occurred at heights from 8 to 15 ft, typically in white fir located in open areas. In Idaho, nests were found in conifers at an average height of 40 ft and ranged from 8 to 55 ft. Of 58 nests at a Colorado study site, 54 occurred in ponderosa pine and four were found in Douglas fir. Nest height was significantly associated with tree height, with the mean nest height around 54% of tree height. On average, western tanager nests were located 63% of the distance between the trunk and the branch tip. This is closer to the bole than found in most studies, and the authors suggest that the conical shape of the ponderosa pine requires nests be placed closer in toward the trunk to provide cover. Canopy cover at nest sites averaged 71%, with a minimum of 31% cover.