The Warbling Vireo (Vireo gilvus) is a small songbird that belongs to the family Vireonidae. These birds have a plain greenish-grey upper body with a lighter underbody, a white eyebrow stripe, and faint wing bars. They also have a hooked bill and a red-brown eye. Adults weigh around 0.3 to 0.4 ounces (8-12 grams) and measure around 4.7-5.5 inches (12-14 cm) in length.

One of the distinguishing field marks of the Warbling Vireo is their constant singing. These birds have a very melodious and continuous warbling song that sounds like “if I see you, I will seize you.” This song is often heard during the breeding season, and it can be used to locate them in the field. They also have a habit of flicking their wings and tails while perched, which can be another helpful identification characteristic.

Warbling Vireos are migratory birds, spending the breeding season in North America and then migrating south to winter in Central America and parts of South America. They breed from Alaska to northern Mexico, and in the eastern United States, they breed from the Great Plains to the Atlantic Coast. During the non-breeding season, they can be found in wooded areas and forests in countries like Costa Rica, Panama, and Venezuela.

In terms of habitat, Warbling Vireos are typically found in deciduous or mixed forests, along streams, or in riparian woodlands. They build cup-shaped nests made of grasses, bark, and spiderwebs in the forks of trees, usually between 5 and 60 feet above the ground. Their breeding season typically runs from May to August.

The Warbling Vireo is an insectivorous bird that feeds on a variety of insects, including caterpillars, beetles, flies, and spiders. They forage for insects by searching the leaves and branches of trees and shrubs. They are also known to occasionally eat fruits and berries. Despite their plain appearance, Warbling Vireos are a joy to observe due to their beautiful singing and lively behavior.