Author: Caitlyn Gillespie

By Anne Seiler, Banding Intern

The Tree Swallow is commonly encountered in natural open areas near trees and water throughout much of NorthAmerica during the summer months. They are recognizable from afar by their dark upper parts and white belly, sloped triangular wings, and distinctive swooping flight. A closer look at these aerial insectivores reveals brilliant iridescent purple and teal plumage. Tree Swallows are very social, often congregating in large mixed flocks with the closelyrelated Violet-green Swallow and other swallow species.

Tree swallows are found primarily in open spaces nearwater, avoiding dense woodlands and busy residential areas. Arriving in southern Oregon and northern California in late-winter to early spring from their wintering areas that range from the southern U.S. to Central America and the Caribbean, this swallow begins its search for a suitable cavity (or, hollowed out hole) nesting site. After one, or possibly two broods, they begin to gather into flocks often a thousand birds strong in July and August to begin their fall migration southward.

Tree Swallow populations are limited by the availability of cavity nesting sites, as their name suggests, in trees, or nest boxes. Placement of nest boxes has helped mitigate the loss of natural nest cavities due to habitat loss and declining woodpecker populations, which initially create cavities used by Tree Swallows and many other species. Although increasing slightly in North America as a whole since 1966, this swallow’s numbers have declined in Oregon during the same period according to Breeding Bird Survey data.

This article appears in the Fall 2008 KBO newsletter

References:

Birds of Oregon, first edition 2003, edited by D.B. Marshall, M.G. Hunter, & A.L. Contreras; Complete Birds of North America, 2006, edited by Jonathan Alderfer Sauer, J. R., J. E. Hines, and J. Fallon. The North American Breeding Bird Survey, Results and Analysis 1966 – 2007, 2008, USGS Patuxent Wildlife Research Center.Tree Swallow Photo: James Livaudais

Bird Bio: Vaux’s Swift
By Melissa Molzahn, KBO Education Specialist (AmeriCorps)

The Vaux’s Swift is often seen flying swiftly overhead, in one direction, then another, at top speed. This small and agile bird rarely perches unless it is nesting or roosting. It can be observed busily hawking all sorts of tiny insects, especially when feeding young.

Generally a summer resident in Oregon, Vaux’s Swifts arrive in late April or early May. They can be found breeding from Canada through California and begin to take off to their wintering grounds in mid-September, travelling as far south as Honduras. Vaux’s Swifts prefer old-growth forest habitat and rely on large-diameter hollow snags for nesting and roosting. Like their eastern cousin, the Chimney Swift, the Vaux’s Swift has been known to utilize brick chimneys in lieu of trees for roosting and nesting.

During migration, these birds stop over at various locations in Oregon and northern California where they roost in groups of over 10,000 birds for several weeks, often in chimneys. Each night they swirl into the chimneys at sunset. KBO will highlight such a location—Eden Valley Farms—at
its Wings and Wine event (see page 1).

Vaux’s Swift populations declined significantly in the 1980s and are believed to be in continued decline. Since oldgrowth forest habitat with hollow snags is so important for this species, forest management practices retaining snags benefit this species. Nest boxes (3.5 m tall and 30 cm square) placed in trees 10-15 m above the ground provide a shortterm alternative to large-diameter hollow trees. As their main source of food is aerial insects, limited pesticide spraying in known roosting locations can ensure that their food supply will not be depleted, especially during the breeding season. Given that large flocks of birds now use chimneys as their migratory roosting sites, maintaining open brick chimneys will also aid the conservation of Vaux’s Swifts.

Learn more about the conservation of Vaux’s Swifts at KBO’s Wings and Wine celebration!

This article appears in the Summer 2008 KBO newsletter.

References:

Birds of Oregon, first edition 2003, edited by D.B. Marshall, M.G. Hunter, & A.L. Contreras; The Birds of North America, first edition 2005, edited by Dr. Alan Poole and Dr. Frank Gill.

Vaux’s Swift Photo: (c) Jim Livaudais

Melissa Molzahn, KBO Education Specialist

The Yellow Warbler, in comparison to other North American wood-warblers, is brilliant yellow. It is often heard singing a beautiful spring song tucked away among willows.

Yellow Warblers breed from Alaska and Canada, south to Baja California, and east throughout central Oklahoma, Arkansas, Georgia, and North Carolina. The winter months are spent from southern California and Arizona to Middle and South America, as well as Amazonian Brazil and Peru. Spring migrants tend to arrive in Oregon during late April to early May. They take off early for their winter homes mid-August to early September. During the breeding season, they are very dependent on riparian habitat for nesting. They are found among willows, cottonwoods and native shrubs. They prefer diversity in plant species, especially within the shrub layer.

Due to their reliance on riparian habitat throughout Oregon and California, the Yellow Warbler is vulnerable to habitat destruction. Livestock grazing in riparian areas can lead to decreased plant diversity and destruction of willows and shrubs. Therefore, conservation plans call for grazing to be actively managed or eliminated. Yellow Warblers are Brown-headed Cowbird hosts. When cowbirds lay their eggs in a Yellow Warbler’s nest the cowbird chick often out competes the warbler chicks for the parents attention.

The Yellow Warbler is a Partners in Flight conservation focal species in California and Oregon and benefits from the protection and restoration of riparian habitats.

This article can be found in KBO’s 2008 spring newsletter. 

References:

Birds of Oregon, first edition 2003, edited by D.B. Marshall, M.G. Hunter, & A.L. Contreras; The Birds of North America, first edition 2005, edited by Dr. Alan Poole and Dr. Frank Gil

Yellow Warbler male singing; Photo James Livaudais

Bird Bio: Spotted Towhee
By: Jonathan Berti, KBO Banding Intern

Many of the bird species that grace this area during the summer months and fall migration have disappeared. To the birding enthusiast, the winter slump in bird diversity may bring dismay. However, it does allow us to appreciate species that choose to rough it through the winter here in the Klamath-Siskiyou Bioregion.

The Spotted Towhee, Piplio maculatus, is a bird whose company we can enjoy in southern Oregon all year long. Although its breeding range extends throughout western North America, from southern Saskatchewan and British Columbia to the highlands of Guatemala, where populations winter, it is found primarily west of the Cascades and in small numbers throughout eastern Cascade lowlands. Distinguished from the Eastern Towhee as a unique species, our rufous-sided resident is distinct, with spotty wings and a characteristic red iris which develops with maturity. It typically inhabits willow thickets and dense growth near a riparian zone, scratching away at the ground loudly as it forages for seeds and berries, or builds its cup-shaped nest, which it usually cuddles in to a nicely formed shallow depression in the earth.

KBO banding interns are well acquainted with the Spotted Towhee, as it is a common capture at most of our regional bird monitoring stations. Nevertheless, Oregon Breeding Bird Survey routes report a 1.0% decline in the Spotted Towhee during the last 4 decades. The Spotted Towhee is not considered threatened in our state, but is known to be sensitive to land-use patterns, such as grazing in riparian areas. Given this, KBO’s monitoring programs are keeping a close eye on resident species like the Spotted Towhee, and are acquiring data that may help ensure that this commonly encountered bird retains habitat locally, and stays common.

This article appears in KBO’s winter 2008 newsletter.
References: 

Birds of Oregon edited by D.B. Marshall, M.G. Hunter, & A.L. Contreras; The Sibley Guide to Birds of North America by D.A. Sibley; The Birder’s Handbook: A Field Guide to the Natural History of Birds of North America by P. Ehrlich, D.S. Dobkin, D. Wheye

Spotted Towhee. Photo: J. Livaudais

Bird Bio: Cedar Waxwing
By: Emily Molter, KBO Wildlife Education Specialist

The Cedar Waxwing is one of only three species worldwide in the Bombycillidae family. Their breeding range extends from British Columbia across Canada, southward to northern California, northern Arkansas, and northern Georgia. Their winter range extends to southern Canada southward through United States and Mexico into Central America. Many birds in Eastern North America prefer the berries of the Eastern Redcedar, hence the “Cedar” in their name. The birds are also named for the red, waxlike tips on the secondary flight-feathers of adult birds. The color of the tips is produced from pigments that are obtained from the birds’ fruit diet.

The Cedar Waxwing eats sugary fruits seven months out of the year. They often gorge themselves on fermented fruit, which leads to a flightless intoxication. Many aspects of the birds’ lifestyle revolve around fruit because it is the main source of their diet. Cedar Waxwings are a social species that can be seen feeding in large flocks. Flocking is an effective way to search for clumped food sources rather than foraging individually. They are partial migrators and move around to find food. Their breeding season is among the latest of North American passerines coinciding with the seasonal availability of ripening fruits. The birds lay eggs from early June through early August.

Cedar Waxwing populations have increased during the last 20 years over much of North America due to the creation of edge habitats with fruiting trees, the planting of fruiting trees and shrubs in rural and urban areas, and the elimination of the use of DDT from agriculture. Even though populations are increasing, Cedar Waxwings still have predators including humans. These birds are vulnerable to collisions with windows. Birds can also be struck by automobiles when feeding on fruit near roadways. Collisions can be minimized by keeping fruiting trees away from these potential hazards. By providing high-protein foods in feeders during the early breeding season and planting fruit-producing shrubs or trees, you can attract Cedar Waxwings to your yard and enjoy their beauty.

This article appears in KBO’s Winter 2007 newsletter.

References:

Birds of Oregon edited by D.B. Marshall, M.G. Hunter, & A.L. Contreras; The Sibley Guide to Bird Life and Behavior by D.A. Sibley; The Birds of North America by G.R. Geupel and G. Ballard

Photo: Brad Sillasen, courteousy of Friends of Sausal Creek

By: Melissa Molzahn, KBO Education Specialist

The Gray Catbird, our featured bird for this issue, is in the Mimidae family. Like many in this family, it mimics calls of other birds. Their name is derived from one call they make that sounds like the mew of a cat. The Gray Catbird winters from the gulf states to Central America, although a small number can be found in New England. They breed in central British Columbia, eastern Canada, and the eastern United States, with additional populations in the central Rocky Mountains, central Arizona and northeast Oregon in the Blue Mountains. This year KBO banders captured, banded and released a Gray Catbird here in southern Oregon, one of several birds unusual to this area that were encountered this year (see page 1).

The Gray Catbird migrates from wintering to breeding grounds beginning in April, arriving in late May through early June. By September they will have left the breeding grounds to return to winter ranges. Their breeding range habitat is very different from that of their winter range. During the breeding season, Gray Catbirds prefer early successional habitat, and in Oregon they are very dependent on dense riparian areas. In their winter range, they seek forested areas. Insects and berries comprise the main components of their diet. In Oregon, they consume elderberry, black hawthorn, mayflies and grasshoppers.

As with many species, catbirds may collide with towers and other tall structures during migration, and at all times are vulnerable to automobiles;some southeast populations have declined. However, Oregon is currently experiencing a gradual expansion of breeding populations as more riparian habitats become protected by improved land management practices. If you live near a breeding population, you can help conserve and enjoy these birds by planting native shrubs and berry bushes for nesting and feeding and by keeping cats indoors.

This article appears in the KBO Fall 2007 newsletter.

References:

Birds of Oregon, First edition 2003; edited by D.B. Marshall, M.G. Hunter, & A.L. Contreras; The Birds of North America, first edition 2005 edited by Drs. Alan Poole and Frank Gill; Birds to Help, 19 Sept. 2007 National Audubon Society, Inc. <http://www.audubonathome.org/birdstohelp/>.

Gray Catbird Photo by Jim Livaudais

Bird Bio: Cassin’s Vireo
By: Amanda Cornell, KBO Field Intern

The Cassin’s Vireo (Vireo cassinii) is one of three vireo species that were once lumped together as the “Solitary Vireo.” It is a small, greenish-gray bird that can be distinguished from other vireos by its white eye rings and lores, which look like a pair of “spectacles” across the top of the beak. The Cassin’s Vireo diet consists largely of insects gleaned from forest foliage. These birds normally breed in conifer/mixed conifer hardwood forests from British Columbia to California and Nevada; they spend their winters between southern Arizona and Guatemala.

The Cassin’s Vireo, known as the “question and answer bird”, has a distinctive, two-part, four-note song, which makes it easy to identify and track in the field. He is the only bird who sounds like he is asking himself a question, then answering himself, too. Male Cassin’s Vireos are also known for singing from their nests, a habit which is appreciated by KBO field interns who are trying to document nesting habits for a study about how prescribed burning within riparian areas affects bird nesting success.

Although populations of Cassin’s Vireo are widespread, they are unevenly distributed throughout the forest; the birds tend to prefer warm, dry forests and usually stay away from cool and open areas. Perhaps the biggest threat to Cassin’s Vireo is their nests being heavily parasitized by Brown-Headed Cowbirds. This parasitism reduces the number of eggs a female vireo lays, decreases the hatching rate of vireo eggs, and increases the rate of starvation of vireo nestlings through competition with the larger cowbird nestlings. However, despite the pressures of nest parasitism, Cassin’s Vireo populations have remained stable, and some have actually increased in recent years.

This article appears in KBO’s Summer 2007 newsletter. 

References:

Birds of Oregon edited by D.B. Marshall, M.G. Hunter, & A.L. Contreras; The Sibley Guide to Bird Life and Behavior by D.A. Sibley.