Eastern Warbling Vireo

Vireo gilvus

Also Known As

• Vireo Gorjeador Oriental (Spanish)
• Vireo Cantor (Spanish)

About

The Eastern Warbling Vireo is a quintessential species of spring and summer across much of eastern North America. This rather drab bird is often hard to spot, hidden up high among the leaves of tall deciduous trees, but its buoyant, easygoing song is hard to miss. One of the most persistent singers through summer, this vireo’s song is considered by many ornithologists and naturalists to be among the most beautiful in its range. Males do most of the singing, but females sing as well — an unusual trait among songbirds in temperate regions. Even more unusual, these birds will even sing while sitting on their nests!

Unfortunately for the vireos, Brown-headed Cowbirds seem to cue in on this species’ habit of singing from the nest. Cowbirds are “brood parasites,” laying their own eggs in the nests of other species, often resulting in the death of some or all of the host’s young. Female cowbirds are quite crafty, even using the movements of parent birds to determine the location of a nest; the more often a parent uses the same paths to and from the nest, the more likely cowbirds are to find it. However, Eastern Warbling Vireos are remarkably efficient at removing cowbird eggs, often puncturing the offending eggs with their bills before discarding them.  Studies of this behavior showed that these vireos seem to recognize cowbird eggs by differences in the pattern of speckles on the shell — and get rid of them 90-100 percent of the time! (snip-MORE-2 calls and a song!)