Hutton’s Vireo, a resident of Western Washington, is not an in-your-face kind of bird. In this region it occupies the understory of Douglas fir forests and thickets along lowland streams. In Edmonds, then, it is a passerine to watch for in areas such as the thickets along Shell Creek in Yost Park and Willow Creek Hatchery as well as the forests of Southwest County Park and Pine Ridge Park. It is even spotted in private yards with the appropriate habitat.
A non-migratory bird, resident within its range, Hutton’s Vireo can be found along the West Coast and into the mountains of Southeast Arizona and Southwest New Mexico. Its range extends through Mexico into northern Central America. It prefers oaks, particularly evergreen oak and pine-oak forests. It also lives in mountain canyons, seeking out sycamores, maples, and willows along streams. It winters in its breeding habitat.
Diet of the Hutton’s Vireo is made up mostly of insects but includes some berries. It feeds on some insects that seem large for a small bird such as caterpillars, beetles, and crickets, as well as spiders. It is known to eat some berries and fruits, including some plant galls. It feeds like a sluggish Ruby-crowned Kinglet, hopping from twig to twig in its search for insects and often hovering to glean an item from vegetation. Its moves have been described as methodical and calculated as it hops between branches. It works a tree thoroughly in its search for food.
This vireo can be confused with the kinglet by novice bird watchers. The two are similar in size, color, and foraging practices. However, while the vireo can be found in Edmonds throughout the year, the kinglet migrates into the mountains for breeding. The kinglet forages so rapidly that it can be difficult to photograph. If you can get an extended view of the bird, it is probably the vireo. While there are many similarities between the two species, the kinglet has a tiny, finely pointed bill and the vireo has a thicker bill with the characteristic vireo hook on the tip.
The male sings constantly during breeding season to defend its nesting territory. Its courtship display involves approaching a female, fluffing out its plumage, spreading its tail, and making a whining call. When a pair has formed, they will build a nest in an oak or conifer, usually 6 – 25 feet above the ground. The nest is round and cup shaped and the rim is woven onto a forked twig. They make their nest out of bark fibers, grasses, mosses, and lichens. They bind it together with spider webs and line it with fine grass. Both adults incubate the four eggs for about two weeks. The young fledge the nest at about two weeks of age. The adults will care for their young for another two weeks or so.
The oldest known Hutton’s Vireo was 13 years and six months old when it was recaptured and re-released in 2006 during banding operations in California. There are up to 12 subspecies of this vireo. There are enough differences between the coastal and interior populations that it is thought to be a candidate for a species split when sufficient research is concluded. A group of vireos is collectively known as a “call.”
The Hutton’s Vireo population, based on the North American Breeding Bird Survey, is estimated at about 840,000 individuals in the U.S. and Canada. There is no estimate for the population south of the U.S. Long-term data show that this species is increasing. Over a 45-year period beginning in 1970, the population has increased by 60%. Although harvesting in Douglas fir forests and of oak in oak-pine woodlands does result in negative population trends for the species, this vireo does not seem to be impacted by aerial insecticide sprays in managed forests.
By April you should be able to hear the monotonous and repetitive single-note song of a Hutton’s Vireo, especially if you take a walk along the creek n Yost Park: www.xeno-canto.org/588297. This is the male’s courtship whine: www.xeno-canto.org/501571.
— By Carol Riddell
Carol Riddell manages the bird education displays, on behalf of Pilchuck Audubon Society and Edmonds Parks & Recreation, at the Olympic Beach Visitor Station.