Vireo Solitarius Solitarius, more commonly known as the Blue-headed Vireo, is a small bird species native to North America. The Blue-headed Vireo gets its name from its distinct blue-grey head and back feathers. However, there are several synonyms for this particular species, including the Solitary Vireo, Blue-headed Greenlet, and Greenlet Solitaire. These synonyms reflect the bird's solitary nature and its distinctive physical features. Blue-headed Vireos are often found in the forested areas of eastern and central North America, and their songs are a familiar sound during spring and summer. Despite their small size, these birds play a crucial role in maintaining the balance of many ecosystems.