There seems to be consensus among the experts that what is most notable about the Warbling Vireo is its song and its unremarkable appearance.

Described by one author as “drab”, the 5.5 inch Warbling Vireo distinguishes itself from other vireos by a plain face broken only by a white eyebrow or “supercilium”, a lack of wing bars, a gray-green cap and back, and whitish underparts.

More than just one of the experts claims that the Warbling Vireo’s song seems to be aptly described by the phrase, “if I see you out of season I will seize you then I’ll squeeze you till you squirt”. This may, in some degree, convey a rapid warbling song with an accented, high pitched, last note. Noted for the length of its song, which has been likened to the House Finch in musicality and the Winter Wren in length, it also distinguishes itself by the number of hours it spends each day singing. Accordingly, many Warbling Vireos even sing while incubating eggs. Interestingly, its nest is often found in close proximity to that of the Least Flycatcher, noted for having possibly one of the shortest of territorial-mating bird songs. (The Least flycatcher song is characterized by the phrase “chi-beck”.)

The Warbling Vireo breeds in both peninsulas of Michigan but is most numerous in the lower peninsula. It is deemed a common transient but an uncommon resident of Leelanau County. Its winter range extends into southern Mexico and Central America.

This vireo prefers more open, mature, deciduous woodlands that border riparian corridors, roads, railroad tracks, and more rural residential areas. It usually arrives in Leelanau during the 2nd week in May and leaves at least by early August.

It builds a hanging, cup shaped nest that hangs from the fork of a horizontal branch extending from the trunk about 10-15 meters from the ground. Both parents incubate the eggs with the whole process from egg to fledging taking about four weeks. The literature indicates , more than not, just one brood a season.

Experts conclude that human changes to the landscape of Michigan in the first half of the 20th century created more open woodlands which resulted in expansion of the range and population of this species. However, since 1966, urban and suburban development, which often eliminated mature trees, coupled with regrowth of forests (younger trees) in other areas brought a net decrease in Warbling Vireo habitat. This, plus heavy pesticide use to control insects and insect-borne diseases, resulted in a substantial decline in Warbling Vireo numbers since 1970.

~bob c.