As the name suggests, the blue-headed vireo is characterized by its blue-grey head and bold yellow wing bars.

[2] The blue-headed vireo has similar plumage year round and does not drastically change its appearance during the breeding season.

solitarius extends from northeastern British Columbia across Alberta, Saskatchewan, Manitoba, Ontario and Quebec and down to southern Pennsylvania and New Jersey.

alticola has a distinct breeding range that includes western Maryland and south, mainly in the Appalachian Mountains, to northern Georgia.

solitarius has the longest migration of the two subspecies and inhabits an overwintering area that includes eastern and southern Mexico to northern Central America.

Recently, however, many hemlocks in eastern USA have been killed by an invasive Asian insect, the Hemlock woolly adelgid (Adelges tsugae), leaving the vireos with fewer nesting options until spring leaf opening begins for deciduous trees.

The males become quite vocal during the breeding season, with the song frequency reaching its height prior to mating and then decreasing after copulation.

Both sexes share a series of calls that are used in both defence of nests, interspecies competition, and communication between breeding pairs while foraging.

[3] When foraging during the breeding season, mated pairs constantly communicate with each other using a series of high pitched chirping calls.

[11] They are equipped with short, strong bills used for processing insect prey with a tough carapace such as beetles.

This large and varied diet is an example of an opportunistic feeding strategy, allowing the blue-headed vireo to be plastic in its ability to adapt to resource availability.

[12] When arriving to the breeding ground in mid-April, male vireos will hold large, individual territories that can range from 1.5–6.6 hectares (3.7–16.3 acres).

During this time, the male and the female will cooperatively build a breeding nest which is typically formed between forking mid-level branches of evergreen and deciduous trees and are composed of twigs and foliage.

Blue-headed vireo males will assist their mates with daytime incubation of eggs, nest construction, and feeding of the chicks.

[10] Also, unlike most bird species, female blue-headed vireos do not attempt any extra-pair copulations with other males.

[10] The increase in male blue-headed vireo parental care is thought to be attributed to the levels of testosterone and prolactin found in the plasma of these birds during the mating season.

[15] Conversely, prolactin is a peptide hormone that is regulated by the hypothalamus that has been found at higher levels in birds that do the majority of incubation.

[3] Common predators of the blue-headed vireo eggs and chicks include blue jays, crows, and squirrels.

[3] The largest contributor to the low nesting success rate of the blue-headed vireo is most likely the parasitic brown-headed cowbird (Molothrus ater).

These birds will often lay their large eggs overtop the existing brood, causing the parents to feed the cowbird which will ultimately starve the infant Vireos.