Western tanager

Appearance

Adults have pale stout pointed bills, yellow underparts and light wing bars. Adult males have a bright red face and a yellow nape, shoulder, and rump, with black upper back, wings, and tail; in non-breeding plumage the head has no more than a reddish cast and the body has an olive tinge. Females have a yellow head and are olive on the back, with dark wings and tail.

Distribution

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.

Behavior

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.

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".

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 330 feet in the Northwest up to 10,000 feet. In the northern portion of their breeding range western tanagers have been observed on sites over 8,300 feet in Oregon down to sites as low as 490 feet in northwestern Washington. In the southern portion of their breeding range, western tanagers are more typical on high-elevation sites. Western tanagers were observed on an Arizona site 8,270 feet in elevation and on a site at 9,500 feet in Nevada.Western tanagers forage in many habitats. Western tanager forages in all successional stages from grass-forb communities to stands of large trees with greater than 70% cover. In western Oregon, western tanagers were not observed using the grass and forb successional stages, but were observed foraging in areas not used for nesting, such as shrub/sapling and young 2nd growth stands typically made up of Douglas-fir.

Although western tanagers forage in many habitats, they are typically observed foraging in forest canopies. For instance, in an area of California primarily dominated by giant sequoia, western tanagers spent 60% to 75% of their foraging time above 35 feet and less than 2% of foraging time below 12 feet. In coniferous forests of western Montana, western tanagers were typically observed foraging in canopy foliage above 26 feet. In mixed conifer-oak forests in California, western tanager foraged from 16 to 92 feet.

In primarily Douglas-fir dominated vegetation in British Columbia, the occurrence of western tanager foraging in various portions of trees and the size of those trees were investigated. Western tanager perched on stems less than 1 inch (

Reproduction

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.

Food

Western tanager obtain their food by foliage gleaning and hawking. The degree to which each of these methods is used apparently varies across locations. For instance, in a California mixed conifer-oak forest consisting mainly of white fir, Douglas-fir, incense-cedar, and California black oak, about 47% of western tanager foraging observations were gleaning, about 40% were hawking, while lunging and hovering occurred in about 6% and 7% of observations, respectively. In contrast, in the mainly Douglas-fir dominated communities of interior British Columbia, gleaning constituted 93.2% of western tanager foraging observations. Hawking only occurred in 3.7% of observations and hovering in 3.1%.

Western tanagers primarily glean from foliage. In the mixed conifer-oak woodland of California, 45% of western tanager foraging observations were foliage gleaning. Western tanagers gleaned from twigs in 10% of observations and from branches in 5% of observations. Hawking constituted the remainder of western tanager foraging observations. In British Columbia, 88.3% of gleaning observations occurred on foliage, 10.5% on branches and twigs, and 1.2% on trunks.

Western tanagers eat fruits and a wide range of insects. Fruits include hawthorn apples, raspberries, mulberries, elderberries, serviceberries, and wild and cultivated cherries. Western tanagers have been observed foraging on Perry's agave nectar. Reports of western tanager eating Eucalyptus nectar, Russian-olive fruits, and human-provided food, including bird seed and dried fruit, were summarized in. Western tanagers are major consumers of western spruce budworms, and they have been observed eating Douglas-fir tussock moth larvae. Hymenopterans, mostly wasps and ants constituted 75% of insects in western tanager stomachs in August. The other insects were beetles, mainly click beetles and woodborers, true bugs, grasshoppers and caterpillars.

Predators

Several birds prey on western tanagers. Remains of a western tanager were found in a red-tailed hawk's nest in Colorado. In southwestern Idaho, western tanager remains were reported in 1 of over 170 prairie falcon nests observed. Northern goshawks, Mexican spotted owls, sharp-shinned hawks and Cooper's hawks are also western tanager predators. Accipiter hawks and jays are major predators of western tanagers. Domestic cats also preyed on western tanager in British Columbia.

Clark's nutcrackers, northern pygmy owls, great horned owls, and jays such as scrub jays, pinyon jays and Steller's jays are typical avian predators of western tanager nests. Other reported nest predators include black bears, prairie rattlesnakes, and bullsnakes

Western tanager nests are parasitized by brown-headed cowbirds. Parasitism rates can be high and can dramatically reduce the number of western tanagers fledged per nest.

Defense

Western tanager nest in 2nd-growth and mature conifer and mixed forests. Western tanagers only breed in stands of pole- to large- sized trees and stands of pole- to medium-sized trees with >70% canopy cover. Western tanager nesting was confined to older 2nd-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 feet; 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 western tanager nests along the branches of deciduous trees was more variable than in conifers. On this site, 56% of western tanager nests were at heights from 21 to 36 feet. Of 9 western tanager nests in an Alberta study site, 8 occurred in white spruce and 1 was found in quaking aspen. Nest height ranged from 20 to 42 feet, with a mean of about 30 feet. 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 feet in height and over 8 inches in diameter at breast height. The average height of nests was 18 feet. In a nearby mixed-conifer forest, nests were found in Douglas-fir and ponderosa pine. Nest trees on this site averaged nearly 50 feet in height and 13 inches in dbh. The average nest height was 16 feet and on average nests were located about 5 feet from the tree stem and 3 feet 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 feet, typically in white fir located in open areas. In Idaho, western tanager nests were found in conifers at an average height of 40 feet and ranged from 8 to 55 feet. Of 58 nests at a Colorado study site, 54 occurred in ponderosa pine and 4 were found in Douglas-fir. Nest height was significantly (p