You have likely heard a red-eyed vireo without even realizing it. One of the most common birds of Beacon, these sparrow-sized songsters spend most of their days in the trees-tops, and are more often heard than seen. The male's non-stop, question and answer phrases, likened to sounding something like this -- where are you?, over here!, what are you doing? -- are repeated throughout the day, even during cabin rest period in the hot summer afternoons.
The males start singing from the time they arrive back in mid-May from their wintering grounds in the Amazon basin until just shortly before they depart again in late August. While it seems he does nothing but sing, the male somehow manages to eat, feeding mainly on caterpillars plucked off the leaves. When he can't be heard singing it's an indication he is feeding his mate, who is sitting on eggs in the nest just below the tree canopy. The female doesn't sing, but stays in contact with the male while she is brooding the eggs and taking care of the nestlings, being sure he provides her with food, and helps raise the young.
Hearing the vireo almost continuously, and from different locations around camp, (there are often several males calling back and forth throughout the day) makes its song very familiar, and readily recognized. It's the best way to identify these plain, light green coloured vocalists, as they rarely descend from the treetops to where they can be easily seen. But they can almost always be heard.
Back in 1952 an observer located in northern Ontario counted how many songs a male red-eyed vireo sang in a 14-hour period, and tallied an astounding 22,197 phrases! While the songs are almost unending, researchers have also discovered that each male has over 30 different songs, as does his neighbour.
Only some of that is understood. For example, there are specific calls used for defending territory and other calls for attracting a mate. Research has also revealed that a male's songs speed up once its mate's eggs have been laid. And there are special calls used for communication between mates, and with the young. That still leaves a lot of singing being done... maybe they are singing just to sing!